Xujun,
You can use my fork or (probably better) create your own fork, push the
branch there and issue a pull request, when you are ready.
Let me know, if you need help with that.
Dmitry.
On Thu Dec 04 2014 at 2:14:02 PM John Peterson <jwpeter...@gmail.com> wrote:
> On Thu, Dec 4, 2014 at 1:03 PM, Xujun Zhao <xzha...@gmail.com> wrote:
> > Hi Folks,
> >
> > I found there were bugs in the ElemCutter class in LibMesh. When I run
> the
> > example under /subdomains/ex3/, It works fine when the refinement times
> > below 4, but error comes out when this value is set 5 or above
> >
> > **----------------------------------------------------------
> -----------------------------------------------
> > adding cut point (d_star, x_star) = 0.610641 , (x,y,z)=(0.610641,
> 0,
> > 0)
> > Inside cut face element!
> > Error: Input must have at least three input vertices.
> > **----------------------------------------------------------
> -----------------------------------------------
> >
> > As another case, even the refinement value is still remains 4, if I
> changed
> > the radius from 0.5 to 0.4, it gives rise the same error.
> >
> > Finally, I checked the source codes and found that it may come from the
> use
> > of endpoint_tol in the member function find_intersection_points().
> > I have two way to fix it. One is just simply remove this tol or use
> smaller
> > tol, which works temporarily, but it will generate problems when devising
> > xfem. The other is to use uniform tol in all the member functions, for
> > example is_inside(), is_outside(), is_cut(), in addition, this tol must
> be
> > set a value dependent of the element size. This is probably more
> reasonable.
> > At least it runs well up to now in my codes. I can share it if it is
> needed
> > :)
>
> Yes, do you have a github account? Please consider forking libmesh
> and pushing your branch for others to take a look at. Ben Kirk is the
> author of ElemCutter; he may have some comments.
>
>
> > In addition, I personally think this ElemCutter can be further improved
> if
> > the element order can be considered. For example, for QUAD9 element, if
> only
> > one node at the middle of an edge in the "-" side of the interface, the
> > others are on the "+" side, then this algorithm cannot find it. In other
> > words, it is only first order accuracy! One solution is to first divide
> the
> > higher order element into subelement according to their nodes, then do
> the
> > subtriangulation in each of them.
>
> I'm not too sure what you mean by "+", "-", etc. but once you have
> some working code/example, we would be happy to take a look.
>
> --
> John
>
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