Re: [deal.II] discontinous contour over elements

2020-01-22 Thread David Eaton
: Re: [deal.II] discontinous contour over elements On 1/18/20 5:02 PM, David Eaton wrote: > I just use tecplot directly visualize the results. The vorticity contour from > my simple code is continuous, and the results from deal.II is discontinuous > (without L2 projection). Ah

Re: [deal.II] discontinous contour over elements

2020-01-21 Thread Wolfgang Bangerth
On 1/18/20 5:02 PM, David Eaton wrote: > I just use tecplot directly visualize the results. The vorticity contour from > my simple code is continuous, and the results from deal.II is discontinuous > (without L2 projection). Ah, I think that is it. Bruno was already on the right track. I bet

Re: [deal.II] discontinous contour over elements

2020-01-20 Thread Bruno Blais
ent:* Sunday, January 19, 2020, 12:49 AM > *To:* David Eaton; dea...@googlegroups.com > *Subject:* Re: [deal.II] discontinous contour over elements > > On 1/18/20 9:25 AM, David Eaton wrote: > > Thank you for your explanations. Basically I formed a weak form of the > PDE for

Re: [deal.II] discontinous contour over elements

2020-01-18 Thread David Eaton
? From: Wolfgang Bangerth Sent: Sunday, January 19, 2020, 12:49 AM To: David Eaton; dealii@googlegroups.com Subject: Re: [deal.II] discontinous contour over elements On 1/18/20 9:25 AM, David Eaton wrote: > Thank you for your explanations. Basically I formed a weak form of the

Re: [deal.II] discontinous contour over elements

2020-01-18 Thread Wolfgang Bangerth
On 1/18/20 9:25 AM, David Eaton wrote: > Thank you for your explanations. Basically I formed a weak form of the PDE > for > one element and numerically integrate it at the Gaussian points based on the > interpolation from the local nodes. Subsequently, I assemble the weak forms > from all

Re: [deal.II] discontinous contour over elements

2020-01-18 Thread David Eaton
, I am puzzled at why I did not read it in the FEM books before. Best David From: Wolfgang Bangerth Sent: Saturday, January 18, 2020, 11:58 PM To: David Eaton; dealii@googlegroups.com Subject: Re: [deal.II] discontinous contour over elements On 1/17/20 9:11 PM

Re: [deal.II] discontinous contour over elements

2020-01-18 Thread Wolfgang Bangerth
On 1/17/20 9:11 PM, David Eaton wrote: > > Thanks the help from you and the others. The issue of discontinuous vorticity > field is resolved. Theoretically, I understand the gradient should be > discontinuous for C0 elements.  However, I still want to convince myself with > a explanation.

Re: [deal.II] discontinous contour over elements

2020-01-17 Thread David Eaton
From: dealii@googlegroups.com on behalf of Wolfgang Bangerth Sent: Thursday, January 16, 2020 12:05 AM To: dealii@googlegroups.com Subject: Re: [deal.II] discontinous contour over elements On 1/14/20 10:04 PM, David Eaton wrote: > > Thank you for your suggestions. I am

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread David Eaton
To: deal.II User Group Subject: Re: [deal.II] discontinous contour over elements An easy way to carry the projection that Wolfgang suggested is to use an L2 projection. The L2 projection matrix is only a mass matrix and your right hand side is constructed by the integral of multiplication

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread David Eaton
Subject: Re: [deal.II] discontinous contour over elements On 1/15/20 9:22 AM, David Eaton wrote: > I understand the C0 element is piecewise linear across elements. However, I > did not experience the same issue in my own C++ code while I use C0 element > with the Petrov Galerkin stabilizat

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread Bruno Blais
half of Wolfgang Bangerth > > *Sent:* Thursday, January 16, 2020, 12:05 AM > *To:* dea...@googlegroups.com > *Subject:* Re: [deal.II] discontinous contour over elements > > On 1/14/20 10:04 PM, David Eaton wrote: > > > > Thank you for your suggestions. I am going

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread Wolfgang Bangerth
On 1/15/20 9:22 AM, David Eaton wrote: > I understand the C0 element is piecewise linear across elements. However, I > did not experience the same issue in my own C++ code while I use C0 element > with the Petrov Galerkin stabilization terms. Actually, I am very confused at > this point. How

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread David Eaton
? Thanks D. From: dealii@googlegroups.com on behalf of Wolfgang Bangerth Sent: Thursday, January 16, 2020, 12:05 AM To: dealii@googlegroups.com Subject: Re: [deal.II] discontinous contour over elements On 1/14/20 10:04 PM, David Eaton wrote: > > Thank you fo

Re: [deal.II] discontinous contour over elements

2020-01-15 Thread Wolfgang Bangerth
On 1/14/20 10:04 PM, David Eaton wrote: > > Thank you for your suggestions. I am going to take a look at Lethe and > compare > with my implementation. In stabilized formulation, I used quadrilateral > element, instead of P2 P1 Taylor-Hood element. The used element is only C0 > element. I also

Re: [deal.II] discontinous contour over elements

2020-01-14 Thread David Eaton
: Tuesday, January 14, 2020 9:53 PM To: deal.II User Group Subject: Re: [deal.II] discontinous contour over elements Dear David, How are you calculating the vorticity? As Wolfgang and Praveen have mentioned, if you are using the DataPostProcessor, then this will use your shape functions

Re: [deal.II] discontinous contour over elements

2020-01-14 Thread Bruno Blais
tions. > > Best > D. > -- > *From:* dea...@googlegroups.com > on behalf of Wolfgang Bangerth > > *Sent:* Tuesday, January 14, 2020 6:24 AM > *To:* dea...@googlegroups.com > > *Subject:* Re: [deal.II] discontinous contour over eleme

Re: [deal.II] discontinous contour over elements

2020-01-13 Thread Wolfgang Bangerth
On 1/12/20 9:17 PM, David Eaton wrote: > My inflow condition is uniform. This formulation and mesh is tested in a > simple C++ code without library. The  large mesh near the inflow does not > give > this problem. > Yes. I am using C0 element. I did calculation using tecplot. However, the >

Re: [deal.II] discontinous contour over elements

2020-01-12 Thread David Eaton
Googlegroup Subject: Re: [deal.II] discontinous contour over elements Is your inflow conditions uniform ? If not then large elements at inflow could introduce errors. If you compute vorticity as curl of velocity pointwise, then the vorticity would be discontinuous at element boundaries, since you

Re: [deal.II] discontinous contour over elements

2020-01-12 Thread Praveen C
Is your inflow conditions uniform ? If not then large elements at inflow could introduce errors. If you compute vorticity as curl of velocity pointwise, then the vorticity would be discontinuous at element boundaries, since you are using only C0 elements for the velocity. If you are averaging