from:"Thomas WICK"

[deal.II] Reminder deal.II Workshop Hannover Sep 11-15, 2023 and extension of deadline

2023-06-28 Thread Thomas WICK


Dear all,

we are briefly extending our deadline for the deal.II Workshop in 
Hannover from Sep 11-15, 2023. Please see


https://www.dealii.org/workshop-2023/

Best regards,

Thomas (on behalf of the organizing team)

--
---
+--+
Prof. Dr. Thomas Wick
Managing Director of the
Institut für Angewandte Mathematik (IfAM)

Leibniz Universität Hannover (LUH)
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org
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Re: [deal.II] some trouble about FEnedelecSZ with hanging node

2023-06-28 Thread Thomas WICK


Dear Xuhong,

the code is internally there with us and the paper is submitted. We are 
currently further polishing, documenting etc. the code, which still may 
take approx. 3-6 months, because
Sebastian who did the implementation also needs to write his 
dissertation now. For this reason, I want to ask a bit for patience, but 
the clear goal is to submit

this code to the official deal.II library.

Best regards,

Thomas W.

--
---
+--+
Prof. Dr. Thomas Wick
Managing Director of the
Institut für Angewandte Mathematik (IfAM)

Leibniz Universität Hannover (LUH)
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org
+--+
---
--



Am 28.06.23 um 16:01 schrieb Wolfgang Bangerth:

On 6/27/23 23:54, xuhong liu wrote:
In this paper, it said that it give a method to deal with hanging 
node using FE Nedelec element, but when i try to constrain the 
Stiffness matrix, it show me a error, i want to know how to do??


Xuhong,
the error message tells you the story: The element you are trying to 
use apparently does not implement hanging node constraints. Since you 
don't show the code, I can only assume that you use the FENedelecSZ 
element, which indeed does not implement these constraints.


The paper suggests that it does, but I don't think that the 
implementation of these constraints have ever been submitted as a 
patch to deal.II. It would probably be useful for you to ask the 
authors about the status of the changes they must have made.


Best
 W.



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[deal.II] deal.II Workshop in Hannover: Webpage online

2023-05-01 Thread Thomas WICK


Dear all,

the webpage of the deal.II Workshop in Hannover is now online:

https://dealii.org/workshop-2023/

For your convenience, we have linked a pre-filled registration email, as 
well as

a template for talk abstracts.

Also, the flyer is updated

https://thomaswick.org/Conference_dealii_Sep_2023/dealii-flyer_v3.pdf

If you have any questions, please do not hesitate to contact us via

dealii2...@conference.uni-hannover.de

Best regards,

Thomas (on behalf of all co-organizers)

--
---
+--+
Prof. Dr. Thomas Wick
Managing Director of the
Institut für Angewandte Mathematik (IfAM)

Leibniz Universität Hannover (LUH)
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org
+--+
---
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Am 22.04.23 um 08:05 schrieb Thomas WICK:

Dear deal.II users and developers,

we are happy to announce that we will host the following workshop [1]:
  10th deal.II Users and Developers Workshop
  September 11-15, 2023
  Leibniz University Hannover, Germany

The workshop itself will start on Monday,
September 11 at 13:00 (1pm) and will feature talks and coding sessions.

It will be preceded by a deal.II crash course starting at 9:00 (9am) 
on Monday morning.

The social program has a conference dinner on Tuesday evening
and a small excursion to Herrenhausen Gardens on Thursday.

The conference email address for registration is
  dealii2...@conference.uni-hannover.de

The registration fee is 100 EUR. More details will follow once the 
registration has been done.


Deadlines, location, webpage, and further information will be 
announced soon.


Best regards,

Thomas Wick, Jan Philipp Thiele, Sebastian Kinnewig, Denis Khimin,
Julian Roth, Hendrik Fischer, Leon Kolditz, Lukas Dreyer
(local organizing committee)

[1] https://thomaswick.org/Conference_dealii_Sep_2023/dealii-flyer_v3.pdf



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[deal.II] deal.II Workshop in Hannover, Germany, September 2023

2023-04-22 Thread Thomas WICK


Dear deal.II users and developers,

we are happy to announce that we will host the following workshop [1]:
  10th deal.II Users and Developers Workshop
  September 11-15, 2023
  Leibniz University Hannover, Germany

The workshop itself will start on Monday,
September 11 at 13:00 (1pm) and will feature talks and coding sessions.

It will be preceded by a deal.II crash course starting at 9:00 (9am) on 
Monday morning.

The social program has a conference dinner on Tuesday evening
and a small excursion to Herrenhausen Gardens on Thursday.

The conference email address for registration is
  dealii2...@conference.uni-hannover.de

The registration fee is 100 EUR. More details will follow once the 
registration has been done.


Deadlines, location, webpage, and further information will be announced 
soon.


Best regards,

Thomas Wick, Jan Philipp Thiele, Sebastian Kinnewig, Denis Khimin,
Julian Roth, Hendrik Fischer, Leon Kolditz, Lukas Dreyer
(local organizing committee)

[1] https://thomaswick.org/Conference_dealii_Sep_2023/dealii-flyer_v3.pdf

--
---
+--+
Prof. Dr. Thomas Wick
Managing Director of the
Institut für Angewandte Mathematik (IfAM)

Leibniz Universität Hannover (LUH)
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org
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Re: [deal.II] ALE framework step-46

2022-06-14 Thread Thomas WICK


Ilya:

Updates to the below link in ANS are here:

http://www.thomaswick.org/gallery_engl.html

and directly on github

https://github.com/tommeswick/fsi

Best regards, Thomas W.

--
---

Prof. Dr. Thomas Wick
Managing Director of the
Institut für Angewandte Mathematik (IfAM)

Leibniz Universität Hannover (LUH)
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org

---
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Am 14.06.22 um 13:17 schrieb Wolfgang Bangerth:


Could you suggest if anyone has any libraries under deal.II, or any 
ideas, articles, how a complete non-stationary problem could be 
implemented using deal.II, possibly by upgrading step-46?


Ilya:
You want to look at this article and accompanying software:
https://journals.ub.uni-heidelberg.de/index.php/ans/article/view/10305

Best
 W.



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[deal.II] Postdoc positions at Leibniz University Hannover

2022-03-30 Thread Thomas WICK


Dear all,

we are hiring at the Institute of Applied Mathematics, Hannover,
up to two Postdocs for 3 years plus possible extension in different
areas inter alia Numerics/Scientific Computing and Optimization.
Knowledge in deal.II is more than appreciated.

Only (major) thing: The positions come (as often typical in the German 
system)
with some teaching load, for which in addition German language is 
required for

some related teaching classes.

On the other hand, we have a young dynamic team
with deep involvement in current deal.II usage and developments
(Maxwell, Navier-Stokes, space-time, fluid-structure interaction,
phase-field fracture, adaptivity).

The official ad is here: https://www.uni-hannover.de/en/jobs/5098/

In case you have questions, do not hesitate to contact me.

Best regards,

Thomas

--
---

Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org

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Re: [deal.II] AFC stabilization method

2021-12-18 Thread Thomas WICK


Dear Shahin, dear Wolfgang,

I had a closer look into the technical details. The implementation with 
regard to deal.II functionalities is fine. Only for

the nonlinear AFC method, the algorithm needs to be worked out.

Best regards,

Thomas

--
---

Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https://thomaswick.org

---
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Am 16.12.21 um 21:04 schrieb Wolfgang Bangerth:

On 12/10/21 03:23, Shahin Heydari wrote:


raw_flux_matrix(i,j) =
      mass_matrix(i,j) * (solution_ul(i) - solution_ul(j))
      -
      mass_matrix(i,j) * (old_solution_u(i) - old_solution_u(j))
      -
      time_step * theta * matrix_D(i,j) * (solution_ul(i) - 
solution_ul(j))

      -
      time_step * (1-theta) * matrix_D(i,j) * (old_solution_u(i) - 
old_solution_u(j));
but the obtained solution is very smeared and the solution does not 
do one complete rotation as it supposed to do. I think the problem 
might be that I have made a mistake in computing mij, dij and ul in 
the global indices.


I suspect that you won't get anyone here who has the interest, 
knowledge, and time to go through your code to check out what is the 
problem. So it comes down to how you can debug the problem and my 
suggestion always is to pick simple cases: For example, choose an 
initial condition that is a step function and for which you can 
compute everything on a piece of paper, run one time step, and compare 
what you get with what you expected.


In any case, the code snippet you show that loops through the matrix 
entries is at least conceptually correct, though I will point out that 
this...


 for(auto jt = sparsity_pattern.begin(i); jt != 
sparsity_pattern.end(i); jt++);

 const auto j = jt->column();

...looks funny to me: The semicolon at the end of the for(...); line 
means that the loop has an empty loop body. But then the variable 'jt' 
would not actually live outside the loop body, and I would have 
expected that you get an error message in the second line. In any 
case, the following line that computes raw_flux_matrix is not within 
the loop body because there are no curly braces, and so does not seem 
to be executed for every 'j'. That doesn't seem right, but I infer 
that the code does not compile that way, and so it must not be exactly 
what you have in your code.



As I know, when we are inside the cell and want to access the value 
of global matrix or vector we can compute the value at the quadrature 
point for example as follow:

  std::vector old_solution_u_values(n_q_points);
fe_values.get_function_values(old_solution_u , old_solution_u_values);


I don't get that comment. I thought you were just working with nodal 
values of the solution for the AFC. Why do you need the values at 
quadrature points?



Now I am just wondering how I can access the entry of the global 
matrix and vector in this case.


And I don't understand this question because you have already figured 
this out.


Best
 W.



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Re: [deal.II] Re: Preconditioner for the time harmonic Maxwell equation

2021-05-24 Thread Thomas WICK

Dear Wolfgang,

Am 21.05.21 um 14:48 schrieb Wolfgang Bangerth:

On 5/21/21 2:23 AM, Sebastian Kinnewig wrote:

The problem you are considering, i.e.
curl ( curl ( E ) ) - k^2 E = 0
is respectively sometimes called the ill-posed Maxwell's equations or
the indefinite Maxwell's equations.
When you are considering only the 2D case a direct solver should be
enough.
But for the 3D case you will need more advanced methods. The most
common approach to solve these equations is via domain decomposition
method (ddm). The basic idea of the ddm is to divide the the domain
into smaller subdomains, where each subdomain becomes small enough so
it can be handled by a direct solver. The ddm for Maxwell is
explained in greater detail in this paper:A quasi-optimal domain
decomposition algorithm for the time-harmonic Maxwell's equations
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0021999115001965=04%7C01%7CWolfgang.Bangerth%40colostate.edu%7Cae145f9e73094301870808d91c31afa9%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637571823692274784%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000=ZE74xHiT8FLjtTNhQCA68VeVYp3BjnWxDl3o%2Brrn8nM%3D=0>.
But it is not easy to build a Maxwell solver based on ddm in deal.II
(I know this, since I am currently working on such a solver by myself).

I am sorry, there is no easy way to do this.

This is somewhat outside of my realm of experience, but I'll chime in
anyway:

Domain decomposition methods conceptually originated from the desire
to use serial codes that were developed in the 1990s and re-use them
in a parallel context. The question was how to connect them into a
parallel code. deal.II does not follow this paradigm: it just
distributes *all* data structures (mesh, matrices, vectors, etc). As a
consequence, it is difficult to press deal.II into service for DD
methods because they philosophically just don't quite fit into the
deal.II world view.

But, I believe you also don't have to because essentially everything
that has been developed in the DD world is also available in the
fully-distributed world deal.II lives in. In the case you describe
above, the key piece is the direct solver that can be run on each
subdomain sequentially. But there are good parallel direct solvers
that one could use -- specifically, I would suggest to explore MUMPS,
which you can access via its PETSc interfaces. (I think I recall that
there is also a Trilinos parallel direct solver, but I've forgotten
its name and we don't have an interface to it.) If you were to
consider something like step-40, where the domain is split into
subdomains, the matrix is split into corresponding sub-matrices, then
a parallel direct solver such as MUMPS can conceptually be thought of
as inverting the diagonal blocks of the matrix corresponding to each
subdomain -- i.e., not so different from what a direct solver applied
to one subdomain in the DD context does. The difference is that in the
DD context, you then have to think of how to stitch the individual
subdomains back together (the boundary or "transmission" conditions
between subdomains) whereas in the fully-distributed,
one-global-linear-system world this is unnecessary.

Thanks for your email concerning DD and deal.II. In general, we agree
that DD in the deal.II context
is not really necessary. Just using a parallel sparse direct solver
(e.g. MUMPS) is not an option because

of memory.

Maxwell is indeed very special and one cannot simply apply well-known
concepts. Of course, Hiptmair proposed in 1998 a multigrid method for
Maxwell. The key is a special
construction of the smoother (Gauß-Seidel-like / multiplicative Schwarz)
and a decomposition of the function spaces.

Of course this paper is highly cited and used, but it does not seem that
idea resolves all difficulties one may have

in Maxwell because of the indefinite structure.

Recently, over the last years, DD seems to be more competitive (e.g.,
Bouajaj et al. JCP 2015) and for exactly this reason, we started

developing a DD solution within deal.II. Our current results are promising.

We need to couple this later with Navier-Stokes and/or solids and for
this reason,
we decided to go with deal.II, despite that other packages (ngsolve for
instance) could

have been better for Maxwell alone.

Any further comments are specifically welcome of course.

Best regards,

Thomas

---
Thomas Wick
Leibniz University Hannover
https://thomaswick.org

Best
Wolfgang

--
---
----
Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.: +49 511 762 3360
Email: thomas.w...@ifam.uni-hannover.de
www:https://ifam.uni-hannover.de/wick
www:https:

Re: [deal.II] Fluid-Structure interaction

2020-10-07 Thread Thomas WICK


Hi Ramiro,

step-46 can be indeed extended to "realistic" FSI (a student of mine did 
it some time ago; but requires a bit of work of course).

As alternative, my deal.II-like tutorial step can also serve the purpose

https://media.archnumsoft.org/10305/

with the code documented as a true deal.II tutorial step. The official 
version is based on 7.0.0.

You may find updates on my webpage

http://www.thomaswick.org/gallery_engl.html

in case of interest.

Other than this I guess Luca Heltai has also some codes online.

Best regards,

Thomas W.

---
Thomas Wick
Leibniz University Hannover
www.thomaswick.org



Am 07.10.20 um 16:28 schrieb Ramiro James Rebolledo Cormack:

Hi everyone.

I'm looking for a solver to solve a fluid-structure problem, like a 
heart valve: the valve is an elastic material, and the blood could be 
considered as an incompressible fluid (evolutionary incompressible 
Navier--Stokes equations).


In step-46 I see a Fluid-Structure interaction implemented in dealii

https://www.dealii.org/current/doxygen/deal.II/step_46.html

but I'm not sure if it is appropiate to a more realistic problem.

I know that the first thing is to know what is the numerical method 
that we want implement, but I'm not sure what is the appropiated 
numerical method to solve this strong coupled problem.


My goal is to implement a model of a valve oppening and close due 
blood pressure (a cilindrical tube with an elastic obstacle in the 
middle). Do you think dealii could be an appropiate code to model 
this? Or is a too big problem?


The other possibility is to use commercial software (COMSOL or ANSIS), 
but due we don't know what they do to solve the problem, I could 
prefer to program "my own" solver, for example with dealii.


I suppose there must be many papers proposing algorithms for these 
types of coupled problems, but I have not found anyone explaining the 
mathematical aspects behind it. So I am very confused about how to 
implement this coupled problem.


I don't know if is too much to ask here, if so, I apologize in advance.

In concrete, my questions are the following:

- what is the numerical algorithm to solve this coupled problem.
- and, is it possible to solve this with dealii? Or is a too big problem.




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----
Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
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www:http://www.thomaswick.org

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Re: [deal.II] Blog post about how we develop deal.II

2020-05-26 Thread Thomas WICK


Hi Wolfgang,



Am 26.05.20 um 04:52 schrieb Wolfgang Bangerth:


Well, not really about how *we* develop deal.II -- but at least about 
my approach in general to developing software:
https://bssw.io/blog_posts/making-myself-better-what-craftspeople-can-teach-us-about-software 

I think that what I describe is how a lot of good programmers think 
about their craft. 


I like that.

Best Thomas

--
---

Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:http://www.ifam.uni-hannover.de/wick
www:http://www.thomaswick.org

---
--




If you're still learning how to be a programmer, this might be of 
interest to you.


See many of you tomorrow for the deal.II workshop!
Best
 Wolfgang



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Re: [deal.II] How to transform the solution on fixed (reference) mesh to that on current (physical) mesh?

2019-11-22 Thread Thomas Wick


Hi Lex,

the difficulty is that the FSI problem is solved in the fixed reference 
domain \hat\Omega.
To have the solution in the physical domain \Omega(t) you need to apply 
the ALE transformation:


A(x) = x + u,

where x are the coordinates of the mesh and u the displacements.


You have three options:

A) In the visualization software visit you need:
1. OpAtts
2. Transform
3. Displace
--> Define therein the displacement operator (vector-valued)
    with the help of x_dis and y_dis.

Activate the operator and apply it to the solution you want to display.


B) In paraview, a similar operator exists that I however do not know in 
detail.



C) You could take the solution vector in the code and apply directly
    therein the displacements u  to the coordinates x
    and then output the solution.

Best regards,

Thomas W.


--
---

Prof. Dr. Thomas Wick
Leibniz Universität Hannover (LUH)
Institut für Angewandte Mathematik (IfAM)
Arbeitsgruppe Wissenschaftliches Rechnen (GWR)

Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:http://www.ifam.uni-hannover.de/wick
www:http://www.thomaswick.org

---
--






Am 22.11.19 um 09:12 schrieb Lex Lee:

Hello,

In recent several months, I have been studying Prof. Thomas Wick's ALE 
transformation method and his implementation codes structure for the 
FSI problem. (https://media.archnumsoft.org/10305/). In his online 
codes file (from line 2695 to 2710, 
https://media.archnumsoft.org/10305/doc/step-fsi_8cc_source.html), he 
stated that


"However, we emphasize that the FSI problem is computed on a fixed 
mesh (instead of moving the mesh as done in other references; we refer 
the reader to the accompanying article and the comments made therein). 
For this reason, the output of the solution in *.vtk format 
corresponds to the solution on the fixed mesh and, therefore, in a 
visualization program, the reader has to post-process the solution. We 
also refer to the MappingQEulerian in the deal.II library, which is 
able to transform the solution to the current (i.e., the physical mesh) "


The attached .vtk file is one of the graphical outputs. As you can 
see, the elastic beam doesn't vibrate as the solution is computed and 
outputted on a fixed mesh, not on the current mesh. (source codes for 
version 9.0 of deal.ii, http://www.thomaswick.org/gallery_engl.html)


Does anyone know the details (or give me a hint) that how to process 
the solution in .vtk format, namely, transforming the solution on a 
fixed mesh to that on a physical mesh?

I appreciate any comments from you guys.

Best,

Lex
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Re: [deal.II] some problems concerning step-14

2018-03-10 Thread Thomas Wick


In addition what Wolfgang said:

1. It would be indeed interesting to
see whether neglecting z_h really yields
the same error, the same effectivity indices,
and/or the same mesh.

2. Going back to your initial questions:
Inserting z_h is the key when classical
a posteriori bounds in terms of the mesh size h
are of interest.

The final goal is usually to obtain an error estimate
in terms of the mesh size h in order to
quantify the order of convergence of your scheme.

For this reason you need to insert z_h such that

|| z - z_h||

to apply interpolation estimates that give you
some h^{a} on the right hand side:

|| z-z_h || = O(h^a)

with the order a.


3. In practice you have indeed different choices
how to evaluate J(u) - J(u_h).

Also some people do not integrate back
into the strong form and work
with a weak form of the error estimator, which
has the advantage that no second-order operators
and partial integration needs to be applied.

From this point of view, it may be that neglecting
z_h could work in practice. But as said above,
a careful study for some model problems
would be useful.


Best Thomas W.

--
++++
Prof. Dr. Thomas Wick
Institut für Angewandte Mathematik (IfAM)
Leibniz Universität Hannover
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:http://www.ifam.uni-hannover.de/wick
www:http://www.cmap.polytechnique.fr/~wick/
++++
--





On 03/10/2018 11:03 AM, Wolfgang Bangerth wrote:

On 03/06/2018 08:40 AM, 曾元圆 wrote:


Now I understand why we need to rewrite the error formula on a cell 
as residual times dual weight. But I'm still a little confused with 
the reason why we must introduce z_h.
Just as you mentioned, if we introduce z_h, then z-z_h is a quantity 
that is only large where the dual solution is rough. But why do we 
need to care about the accuracy of z here? I think the only  thing we 
need to care about is the value of z on that cell, because z is a 
quantity that represents how important the residual on that cell is.


No. z tells you how important the *locally generated error is for the 
global error functional*. (That is because z is the Green's function 
associated with your error functional.) But you don't have the local 
error. All you have is the local residual.



My understanding is: now the dual_weight z-z_h does not only 
represent how important the residual on a certain cell is, but also 
tells us some information about how good the dual solution on that 
cell is. But another problem is, does z-z_h still has the same 
tendency as z?


Almost. Think of it as z-phi_h where you can choose phi_h as you want. 
For example, on each cell you can think of choosing phi_h so that it 
cancels the constant and linear term of the Taylor expansion of z. 
Then z-z_h would contain the quadratic and higher order Taylor terms, 
i.e. something like z''*(x-x0)^2 where x0 can be chosen as a point on 
the cell.



If not, how z-z_h can represent the importance of a certan cell as z 
can?
I'm not sure if my understanding is correct. I tried to run the code 
using only z as dual_weights, and I found the result almost the same 
as that using z-z_h.


Nice idea to try this out. Do you get "almost the same" overall error 
estimate, or "almost the same" mesh?


I think all of these are good questions to ask. Although I have worked 
on this for a long time, I can not actually give you a particularly 
good answer for all of this. I am sure others who are more versed in 
the theory of errors, residuals, etc could tell you the precise reason 
for why it is in fact necessary to subtract z_h. The best I can say is 
that that's the way I've always seen it done, and while I have a vague 
idea why that is so (see above), I can't say that I can describe it 
well enough to explain it.



Finally, I am certainly glad to submit patches to deal.II and make my 
own contribution. But I didn't fork deal.ii on my github account yet, 
and this is relatively a small issue, so I will be glad if you can do 
it for the moment.


OK, I will take care of this then.

Best
 W.



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Re: [deal.II] Re: Crack propagation

2018-02-19 Thread Thomas Wick


Dear Yaakov,

which article do you mean? Please give the exact reference including 
author names.


I do not know a priori whether they have different material parameters, 
another

stress-strain splitting, etc.

The reason for different results can be anything. One needs to do a 
careful 1-by-1

comparison.

Best regards,

Thomas W.


On 02/19/2018 09:26 AM, Thomas Wick wrote:

Dear Yaakov,

which article do you mean? Please give the exact reference including 
author names.


I do not know a priori whether they have different material 
parameters, another

stress-strain splitting, etc.

The reason for different results can be anything. One needs to do a 
careful 1-by-1

comparison.

Best regards,

Thomas W.



On 02/17/2018 01:41 AM, feap...@gmail.com wrote:

Dear Prof. Wick,

I have used isotrope formulation for miehe shear loading (without 
local refinement). I ca not see two crack branching which is 
described in the article (A review on phase-field models of brittle 
fractureand a new fast hybrid formulation)


I attach the test results.

Thanks for your answer!

Kind regards,
Yaakov

On Saturday, February 3, 2018 at 7:20:27 AM UTC+1, Thomas Wick wrote:

Hello,

there are two flags in the parameter file that you need to change:

set Decompose stress in rhs   = 0.0
set Decompose stress in matrix   = 0.0


Thomas W.


-- 
++++

Prof. Dr. Thomas Wick
Institut für Angewandte Mathematik (IfAM)
Leibniz Universität Hannover
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:thoma...@ifam.uni-hannover.de 
www:http://www.ifam.uni-hannover.de/wick
<http://www.ifam.uni-hannover.de/wick>
www:http://www.cmap.polytechnique.fr/~wick/
<http://www.cmap.polytechnique.fr/%7Ewick/>
++++
-- 


On 02/03/2018 03:24 AM, fea...@gmail.com  wrote:

Dear Prof. Heister, I would like to just test  isotrope
formulation of phase -field model (no compression/tension
modification), how could I modify the codes (in a simple way)? I
am sorry that I am just a beginner of DealII. Best On Tuesday,
December 5, 2017 at 7:01:17 PM UTC+1, Timo Heister wrote:

> If I use your user element, I have to use OPEN MPI? now I
have some issues > with Open MPI in Deal.ii What do you mean
by "user element"? The example code in question requires
deal.II to be configured with MPI. What vendor you use
(OpenMPI, MPICH, ...) is up to you. -- Timo Heister
http://www.math.clemson.edu/~heister/
<http://www.math.clemson.edu/%7Eheister/> 


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Re: [deal.II] Re: Crack propagation

2018-02-19 Thread Thomas Wick


Dear Yaakov,

which article do you mean? Please give the exact reference including 
author names.


I do not know a priori whether they have different material parameters, 
another

stress-strain splitting, etc.

The reason for different results can be anything. One needs to do a 
careful 1-by-1

comparison.

Best regards,

Thomas W.



On 02/17/2018 01:41 AM, feap...@gmail.com wrote:

Dear Prof. Wick,

I have used isotrope formulation for miehe shear loading (without 
local refinement). I ca not see two crack branching which is described 
in the article (A review on phase-field models of brittle fractureand 
a new fast hybrid formulation)


I attach the test results.

Thanks for your answer!

Kind regards,
Yaakov

On Saturday, February 3, 2018 at 7:20:27 AM UTC+1, Thomas Wick wrote:

Hello,

there are two flags in the parameter file that you need to change:

set Decompose stress in rhs   = 0.0
set Decompose stress in matrix   = 0.0


Thomas W.


-- 
++++

Prof. Dr. Thomas Wick
Institut für Angewandte Mathematik (IfAM)
Leibniz Universität Hannover
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:thoma...@ifam.uni-hannover.de 
www:http://www.ifam.uni-hannover.de/wick
<http://www.ifam.uni-hannover.de/wick>
www:http://www.cmap.polytechnique.fr/~wick/
<http://www.cmap.polytechnique.fr/%7Ewick/>
++++
-- 


On 02/03/2018 03:24 AM, fea...@gmail.com  wrote:

Dear Prof. Heister, I would like to just test  isotrope
formulation of phase -field model (no compression/tension
modification), how could I modify the codes (in a simple way)? I
am sorry that I am just a beginner of DealII. Best On Tuesday,
December 5, 2017 at 7:01:17 PM UTC+1, Timo Heister wrote:

> If I use your user element, I have to use OPEN MPI? now I
have some issues > with Open MPI in Deal.ii What do you mean
by "user element"? The example code in question requires
deal.II to be configured with MPI. What vendor you use
(OpenMPI, MPICH, ...) is up to you. -- Timo Heister
http://www.math.clemson.edu/~heister/
<http://www.math.clemson.edu/%7Eheister/> 


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Re: [deal.II] Re: Crack propagation

2018-02-02 Thread Thomas Wick


Hello,

there are two flags in the parameter file that you need to change:

set Decompose stress in rhs   = 0.0
set Decompose stress in matrix   = 0.0


Thomas W.


--
++++
Prof. Dr. Thomas Wick
Institut für Angewandte Mathematik (IfAM)
Leibniz Universität Hannover
Welfengarten 1
30167 Hannover, Germany

Tel.:   +49 511 762 3360
Email:  thomas.w...@ifam.uni-hannover.de
www:http://www.ifam.uni-hannover.de/wick
www:http://www.cmap.polytechnique.fr/~wick/
++++
--




On 02/03/2018 03:24 AM, feap...@gmail.com wrote:

Dear Prof. Heister,

I would like to just test  isotrope formulation of phase -field model 
(no compression/tension modification), how could I modify the codes 
(in a simple way)?


I am sorry that I am just a beginner of DealII.

Best


On Tuesday, December 5, 2017 at 7:01:17 PM UTC+1, Timo Heister wrote:

> If I use your user element, I have to use OPEN MPI? now I have
some issues
> with Open MPI in Deal.ii

What do you mean by "user element"? The example code in question
requires deal.II to be configured with MPI. What vendor you use
(OpenMPI, MPICH, ...) is up to you.

-- 
Timo Heister

http://www.math.clemson.edu/~heister/
<http://www.math.clemson.edu/%7Eheister/>

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Re: [deal.II] Re: Steps 14 in 3D

2017-07-08 Thread Thomas Wick


Dear Elena,

it is essentially as in all other deal.II steps: you need to go through 
the code
and check which parts depend explicitly on the dimension. As you say 
yourself, you definitely

need to provide

- a 3D mesh
- possibly modify the boundary conditions.

Furthermore, you need to:

- check if the primal equation needs to be adapted (in this example not!)
- check whether the adjoint (dual) equation (right hand side) needs to
  be modified
- check whether the error estimator contains parts that are only
  valid for 2D (I remember that in this specific example it is already 
dimension-independent)


Once you have this, I would just try to run the code and see what happens
and then work in debug mode or with gdb to find out where the codes crashes.
The compiler will tell you.

Best Thomas

--
++++
Dr. Thomas Wick
Maitre de conferences / Assistant Professor

Centre de Mathematiques Appliquees (CMAP)
Ecole Polytechnique
91128 Palaiseau cedex, France

Email:  thomas.w...@cmap.polytechnique.fr
Phone:  0033 1 69 33 4579
www:http://www.cmap.polytechnique.fr/~wick/
++++
--




On 07/08/2017 08:18 AM, Jean-Paul Pelteret wrote:

Dear Elena,

You have asked a question that is beyond the scope of expectation for 
this forum 
<https://groups.google.com/forum/#%21topic/dealii/GRZMUTLIm2I>. Right 
now you're essentially asking someone to do your preliminary work for 
you, which is unfair. Part of the way to learn deal.II and become 
familiar with the workings of code that forms the foundation of your 
work is to play with it. If you have any specific questions regarding 
issues that you encounter while trying to modify the example, feel 
free to ask them and we'd be happy to help where we can.


Best,
Jean-Paul

On Friday, July 7, 2017 at 4:06:39 PM UTC+2, Elena Greco wrote:

Dear Friends,

I want to change step 14 to run a 3D model.
I know that in deal ii many parts are dim independent and by
changing dim to 3, automatically many parts work for 3D and do not
need any modification.

I want to know, for 3D model which parts should I change in step 14.
In general I know that I should modify mesh and BC parts but step
14 is complicated and I need a bit more detail list for step 14.
I am asking this question because I want to have complete list of
the parts which I should modify and I do not want to miss any part.

Best regards.
Elena


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++----++
Dr. Thomas Wick
Maitre de conferences / Assistant Professor

Centre de Mathematiques Appliquees (CMAP)
Ecole Polytechnique
91128 Palaiseau cedex, France

Email:  thomas.w...@cmap.polytechnique.fr
Phone:  0033 1 69 33 4579
www:http://www.cmap.polytechnique.fr/~wick/
++++
--

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Re: [deal.II] Re: Problem with postprocessor

2017-06-07 Thread Thomas Wick


Hi Seyed,

I am old-fashioned in this sense: indeed yes, I just plot the output 
into a file:


make run | tee my_results.txt

Then I `grep' the quantity (for example PStress) that I want and then 
plot with gnuplot.


Of course it would be a bit more efficient to write all output of 
interest directly into
a file. Honestly this is not so difficult either with deal.II functions 
or directly

C++ (fstream, write, etc.).

In step-7 you will get an idea how to use deal.II functions for latex 
output.


Best Thomas


On 06/07/2017 12:26 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Thomas,

Would you be so kind to tell me how am I able to create the 
load-displacement curves like in your paper? Did you use gnuplot?
And does deal.II have a built-in function that allows one to output 
the necessary data directly to gnuplot or to a textfile?


Thank you in advance.

Kind regards,
Seyed Ali
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--
++--------++
Dr. Thomas Wick
Maitre de conferences / Assistant Professor

Centre de Mathematiques Appliquees (CMAP)
Ecole Polytechnique
91128 Palaiseau cedex, France

Email:  thomas.w...@cmap.polytechnique.fr
Phone:  0033 1 69 33 4579
www:http://www.cmap.polytechnique.fr/~wick/
++++
--

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Re: [deal.II] Re: Problem with postprocessor

2017-05-31 Thread Thomas Wick




On 05/31/2017 05:00 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:



The only thing I changed a bit is the integration from quadratic to 
linear, but I am not sure, if seeting quadrature_formula(2)



In

https://github.com/tjhei/cracks/blob/master/cracks.cc

line 982,

you need to change the "degree", but it should be already "1".

And the quadrature formula - what you mentioned above - should be 
sufficiently high, "2" should do the job.



Best Thomas






alone is enough for linear shape functions. You also had 
face_quadrature_formula or this Lobatto integration.
Would you be so kind and explain what lines I have to change in order 
to obtain linear shape functions and not quadratic like set in the 
original version?

How many changes and the code would help a lot.
Just to be sure I did it correct.

Thank you.

Best,
Seyed Ali
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++----++
Dr. Thomas Wick
Maitre de conferences / Assistant Professor

Centre de Mathematiques Appliquees (CMAP)
Ecole Polytechnique
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Email:  thomas.w...@cmap.polytechnique.fr
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Re: [deal.II] Re: Problem with postprocessor

2017-05-31 Thread Thomas Wick



I hope you could explain me what could cause such a behavior in your 
implementation that deal.II gives different values for duh although 
the same postprocessor implementation is being used.

Is it because of the coupled formulation?



I really would think so. What you could do is to disable the phase-field 
variable
such that you have in both codes really only elasticity and have a fair 
comparison.


How do you do this?

You could erase in our code (Heister/Wick) all the phase-field (pf) 
appearances in the solid

mechanics equations. Then the phase-field values do not enter any more
and led to wrong results with the fracture.


Best Thomas






Thank you for your help so far.

Kind regards,
Seyed Ali
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Re: [deal.II] Re: Problem with postprocessor

2017-05-31 Thread Thomas Wick


Hi Toby,

I appreciate your additional comments.

Thanks and best,

Thomas

On 05/31/2017 02:16 PM, Tobi Young wrote:
I'm going to jump in with one of my random comments uninvited. 
Hopefully you don't mind. :-)



I already run the example with uniform mesh, hence global
refinement with 0 refinement cycles.
The problem is, a specimen with 100 or 1000 elements is difficult
to check due to the terminal output being flooded.


I think what Thomas is kindly trying to point out is, that a single 
cell is a useless test case for almost all possible test cases that 
deal with practical problems.


It seems your case is one of many examples.

Try 16 cells. Look at the data and then try 32 cells and compare. 
Maybe write a procedure that will look at the data for you and put 
useful results into a file for you to look at? Can you plot results 
with gnuplot (for example)?


Machines are stupid, they only can do what you tell them to do! So, 
why not reserve a day or so to calmly write the algorithms needed to 
extract the data you want in a way you can visualise?


You need to do your analysis in some way. You can not expect a machine 
to do things for you. You have to instruct her what it is you want to 
be done. Write the code...   :-)


That is scientific computing.

I could just output the result for one element, but then wheres
the difference.


Big difference in numerical analysis of this kind! ;-)

I am not being unkind - though, maybe its time to get dirty, write 
some code, and look at the numbers, in order to figure out where the 
problem lies. If you can do that, there are alot of dealii users and 
developers that will help you out, and you'll get there in the end. :-)


Best,
   Toby



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Re: [deal.II] Re: Problem with postprocessor

2017-05-31 Thread Thomas Wick




On 05/31/2017 01:31 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Thomas,

I already run the example with uniform mesh, hence global refinement 
with 0 refinement cycles.
The problem is, a specimen with 100 or 1000 elements is difficult to 
check due to the terminal output being flooded.


This I understand, but you could write everything into a file ...


I could just output the result for one element, but then wheres the 
difference.


See below.


Don't you ever do some simple FE patch examples?


Never. Because simply the theory of finite elements tell you that the 
discretization error is so huge

that any result is nearly meaningless.


If I am interested in stress values or the stress tensor, but I am not 
sure if this
will help you or if you are interested, is to compute typical quantities 
of interest.

That is not only a point-wise stress, but for example a line integral:

\int_{part of boundary} \sigma\cdot n \ds.

Or indeed you compute the stress in a specific point in the domain
but really using more than one element.

Many examples and benchmarks for elasticity and plasticity and also 
quantities

of interest (goal functionals) are given in the book:

http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0471496502.html


For instance two examples from this book with point values of stresses 
(e.g., \sigma_yy),
again on more than one element, are provided in the deal-DOpElib 
library, see pages 42 - 45 on


http://wwwopt.mathematik.tu-darmstadt.de/dopelib/description_full.pdf


Best Thomas




Kind regards,
S. A. Mohseni
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Re: [deal.II] Re: Crack propagation

2017-04-07 Thread Thomas Wick


Dear Seyed Ali,

very good!

However, when you write that you solve "exactly" my/our (Timo and I)
code then I would assume it is really "exactly" that version.

When you add other things, of course this might accelerate or slow
down the code :)

Next time, please write first if you solve "exactly" the same code or not :)

Anyhow: good that you found the reason.

Best regards,

Thomas


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On 04/07/2017 01:10 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Thomas,

I found the problem. Your version works exactly like discussed in your 
paper, even faster with my Intel i7, namely around 1400 s. The 
timeconsuming part is the computation of my B-operator.



The B-operator computation is implemented inside*assemble_system (bool 
residual_only):*

*
*
|
for (; cell != endc; ++cell)
if ( cell->is_locally_owned() )
{
fe_values.reinit(cell);

local_matrix = 0;
local_rhs = 0;

int cell_index = cell->active_cell_index();

...

// COMPUTE: B-Operator

for (unsigned int q = 0; q < n_q_points; ++q) // loop over 
integration/quadrature points (GPs)

{
 b_operators[cell_index][q] = Tensors::*get_b_operator*(fe_values, 
dofs_per_cell, q);

}

*B* = b_operators;

// Old Newton iteration values
fe_values.get_function_values(rel_solution, old_solution_values);
fe_values.get_function_gradients(rel_solution, old_solution_grads);

...

}
|

The variable *B *is a history variable I created to store the 
B-operator history and has been initialized in the main class function 
according to:


|
std::vector<std::vector<FullMatrix>>B; // temporary cell 
storage solution (inefficient!)

|


The function *get_b_operator()* which is called within the Gauss 
points loop is implemented in Tensors:


|
template
FullMatrix get_b_operator (const FEValues _values, 
const unsigned int dofs_per_cell, const unsigned int q)

{
FullMatrix tmp(dim, GeometryInfo::vertices_per_cell);

// Remark: For vector-valued problems each column is a value for each 
value of the solution variable, hence here 3 DoFs per node 
(dofs_per_cell = 12)!

for (unsigned int i = 0; i < dofs_per_cell; i += 3)
{
const unsigned int index = i / 3;

// COMPUTE: B-operator (Remark: This version has to be extended for 3D!)
tmp[0][index] = fe_values.shape_grad_component(i, q, 0)[0];
tmp[1][index] = fe_values.shape_grad_component(i, q, 0)[1];
}

return tmp;
}
|


I assume (as I already wrote within my comments inside the above code) 
that this kind of cell storage for matrices turns out to be quite slow 
and inefficient. Jean-Paul offered me once to use the new 
CellDataStorage function, if I remember correctly. Isn't there a nice 
and elegant way to store data in each Gauss point and cell without 
loss of computational time? Or am I able to pass the B-operator to 
another function somehow after I have solved the system? Something 
similar to your predictor-corrector scheme. It seems you somehow pass 
data more efficiently from one function to another function even after 
you solved the system. Do you also pass cell data from a function 
before solving to a function after solving?


Best,
Seyed Ali



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Re: [deal.II] Re: Crack propagation

2017-04-06 Thread Thomas Wick


Dear Seyed Ali,

no idea, but possible reasons :

1. Do you compute on the same mesh?

2. do you compile in release mode or debug mode?
Release is faster.

3. Possibly you can optimize deal.Il with respect to the CPU etc.
On my desktop computer at work, deal.II is 2 - 4 times slower than
on my laptop for instance.

Best Thomas

On 04/06/2017 04:50 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Thomas,

I was wondering, why my computation is rather slow compared to your 
results within your paper. For instance regarding the shear test you 
mention that for global refinement the total time amounts to 5036 s. 
In my case each step takes around 200 s which would result in a total 
time of 30200 s (for 151 steps). What could be the reason?


Attached you find the terminal output from your approach.




Kind regards,
S. A. Mohseni
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Re: [deal.II] Re: Crack propagation

2017-04-01 Thread Thomas Wick


Dear Seyed Ali,

now I understand better. What you could do is to disable
the phase-field functionality in the program or to
choose G_c very high such that the phase-field will never
be activated. Then you only have the elasticity part
and can compare.



||

By the way Thomas, if you don't remember me, we already met after your 
GACM 2015 conference presentation and within the GAMM phase-field 
workshop :)


Indeed. I did not make the relation ...


Maybe you remember: Back then you already mentioned that h < epsilon 
to resolve the transition of the phase-field variable. Nevertheless, 
this is true for the cracked region, but if you have only elastic case 
the mesh size will not matter. This is just to allow a correct and 
accurate resolution and regularization of the phase-field crack region.


Yes. This is correct. However, in case you do not know when the
crack starts propagating and phase-field values are going to zero
in the crack region, one has to be cautious with the number of
mesh cells (sufficiently enough), otherwise the relation h < epsilon
will be violated.

But again: even if you only have elasticity and thus do not
need to take care of h < epsilon; too coarse
mesh cells have a huge discretization error and are therefore
NOT accurate and thus questionable in their meaning!



Best regards,

Thomas






Kind regards,
S. A. Mohseni
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Re: [deal.II] Re: Crack propagation

2017-03-31 Thread Thomas Wick


Dear Seyed Ali,

what do you mean by "one element test"?

Really to compute on one single element ?

This can never work:

1. First of all the phase-field will not be resolved
because of the regularization parameter eps.

2. This contradicts any idea of numerical methods
to have a reasonable number of mesh elements
and then do mesh refinement with as many mesh elements as possible
(w.r.t. to memory and computational cost)
in order to approach the underlying continuous problem.


Therefore, the short answer is: no - a one element test is not possible
and it is also not reasonable to envisage it.

Best regards,

Thomas

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Centre de Mathematiques Appliquees (CMAP)
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Email:  thomas.w...@cmap.polytechnique.fr
Phone:  0033 1 69 33 4579
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++++
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On 03/31/2017 04:39 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Thomas,

I tried what you suggested and it works. Thank you :)
There is a slight problem though when I try to compute the same 
example with the same boundary conditions for the unit_square_4.inp 
file. I am trying to run a one element test using your phase-field 
approach. It works, but there is no residual value and next to it I 
obtain a -nan below Reduction. Is it possible to run a one element 
test with the same settings or do I have to modify something (such as 
rhs computations or boundary value functions)?


Kind regards,
Seyed Ali

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Re: [deal.II] Crack propagation

2017-03-30 Thread Thomas Wick


Dear S. A. Mohseni,

the Gauss points are assigned in that program as always in deal.II:

 QGauss quadrature_formula(degree + 2);

and in the argument, you can change to whatever number you want:

QGauss quadrature_formula(n);

with n=1 or n=2 or n = 3 for instance.

Best regards,

Thomas W.

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Centre de Mathematiques Appliquees (CMAP)
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Phone:  0033 1 69 33 4579
www:http://www.cmap.polytechnique.fr/~wick/
++++
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On 03/30/2017 03:13 PM, 'Seyed Ali Mohseni' via deal.II User Group wrote:

Dear Timo Heister and Thomas Wick,

I am trying to run your phase-field crack propagation example, namely 
the single edge notched tension test, with less than 9 Gauss points.
Hence, the fe variable is initialized using FE_Q(degree) where 
degree cannot be 0. This means degree should always be >1 here in 
order to make things work, but how can one compute the examples with 1 
or 4 Gauss points? Is the code not suited for what I am trying to 
achieve or where are the parts I have to change in order to make it 
work for less integration points. To be honest, I don't even see the 
point of having 9 integration points for a 4-noded quadrilateral or am 
I overseeing something?


Thank you in advance.

Kind regards,
S. A. Mohseni
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Re: [deal.II] Re: Phase-fiield crack sample with predictor-corrector

2016-07-19 Thread Thomas Wick

> Eureka,
> I have fixed the Problem.Thank you again.

You are welcome - very good.

Best Thomas

Best Reza.

Am Dienstag, 19. Juli 2016 21:35:07 UTC+2 schrieb Reza Zargar:

   Dear Thomas,

   thank you so much.
   I have downloaded it and tried to recompile it but this time I get
   the same error as last time,so :
   /usr/local/lib/libdeal_II.g.so.8.4.1: error: undefined reference to
   'Epetra_MpiComm::Epetra_MpiComm(int)' ! . The compiling of the last
   example was successful since I compiled every thing with gcc,but
   this time it appears again although I have compiled the dealii and
   trilinos with same compiler,namely gcc.Now I am trying to fix
   it.Thank you in any case.

   Best Reza

   Am Dienstag, 19. Juli 2016 10:14:36 UTC+2 schrieb Thomas Wick:

   Dear Reza!

   On 07/18/2016 04:30 PM, Reza Zargar wrote:

and also there is an example in paper called "Example
4-Symmetric three point bending" which is not contained in the
folder crack-master. How can I have it to carry out as a
sample?Thanks again.

   Is now online on github.

   Best Thomas

Am Montag, 18. Juli 2016 15:21:42 UTC+2 schrieb Reza Zargar:

Dear all,

I would like to know if I find anywhere an interpretation
of the code of crack-master for phase-field fracture
sample. I have gotten the example and I have to
investigate if it works without the predictor-corrector
too or not, and to do this I should understand how does it
work. although there is some comments for the code but
these are not adequate as the samples as in steps.Thank you.
P.S. the website that I got the example is follows:

https://github.com/tjhei/cracks

<https://www.google.com/url?q=https%3A%2F%2Fgithub.com%2Ftjhei%2Fcracks=D=1=AFQjCNFeehiYReIl1GoFEbOPUdzD6xAhtA>

Kind regards
Reza

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Re: [deal.II] Re: Entry of the own problem in dealii

2016-06-22 Thread Thomas Wick


Dear Reza!

Actually this specific code follows
very much the general structure of deal.II tutorials.

If you want (or need) to learn this first, I always recommend
to work through the first six tutorials.

Then for vector-valued problems, step-22 is important.

For the specific solver, we made use of step-41/42.

Now for your specific questions, I would go as Wolfgang
said: if you know your crack location, then you set-up
refinement indicators there and refine the mesh there.
Local mesh refinement is explained in step-6 of the deal.II tutorials.

For the input of the geometry of different files formats
are supported:

https://www.dealii.org/8.4.0/doxygen/deal.II/classGridIn.html

Examples can be found in many deal.II tutorials steps how
they are used.

Best Thomas


++++
Dr. Thomas Wick
Research Scientist at RICAM Linz, Austria

Email:  thomas.w...@ricam.oeaw.ac.at
www:http://people.ricam.oeaw.ac.at/t.wick/
++++
--

On 06/22/2016 09:33 PM, Reza Zargar wrote:
Thanks alot for your answer. I wrote a post for you but I think it was 
not posted successfully, so if you see my answer probably twice I 
appoligize to you for it. I have allready read the paper that is done 
in dealii and I saw the homepage that you gave me and downloaded the 
code. But actually my problem is that I have to input my geometry in 
dealii and refine it in my certain direction of the crack, which is 
for me not clear in the paper how it has been done in the software. I 
know the theory of it but how to implement it with the software is my 
problem. It would be nice if you could tell me how can I do it or if I 
can fine somewhere accordingly its tutorial or the way of it.Thank you.


Kind regards
Reza


Am Mittwoch, 22. Juni 2016 07:54:59 UTC+2 schrieb Thomas Wick:

Dear Reza,

there is also a deal.II gitHub "tutorial" on phase-field fracture,
which exactly addresses your questions:

https://github.com/tjhei/cracks <https://github.com/tjhei/cracks>

Best Thomas

++----++
    Dr. Thomas Wick
Research Scientist at RICAM Linz, Austria

Email:thoma...@ricam.oeaw.ac.at  
www:http://people.ricam.oeaw.ac.at/t.wick/  
<http://people.ricam.oeaw.ac.at/t.wick/>
++++
--

On 06/22/2016 07:07 AM, ha.ba...@gmail.com  wrote:

Hi

1) You can use UCD or Abaqus mesh format as input.
2) The best choice in mesh refinement is phase field variable. I
have used phase field as control variable. Loop over cells and
check the phase field variable in the cells. If phase field
variable was greater than a limit then refine the cell. In
addition you can use energy.

Best,
H.

On Tuesday, June 21, 2016 at 11:23:07 PM UTC+4:30, Reza Zargar
wrote:

Dear all,

currently I do my master thesis and firstly I have to do
adaptive mesh refinement for a brittle fracture in 2D using a
phase-field approach but with my own geometry. I would like
to ask you how can I input my geometry in dealii-8.4.1, which
version I use and how can I command that only the area has to
be refined, which is cracked. I have seen the second one in
step-12 but I could not find out how can I change the
geometry and the crack direction on it. I took a look at the
FAQ, the tutorials and the videos too but unfortunately could
not find the answer which I need. Thank you in advance for
your answer.

Best regards

Reza

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