[Gmsh] integration, spikes
t.eschner at dokom.net
t.eschner at dokom.net
Mon Oct 26 19:38:57 CET 2020
Thank you very much (I am very late, but I hope not too late).
After a forced pause I made a new attempt and found that a naive cut
produced a quite distorted mesh that caused numeric problems, I
assume. I am happier with plugin(CutGrid) now.
After fixing the parameters, plugin(Intergrate) started to provide
values with actually sufficient accuracy, but I will switch to global
quantities later, as you suggested.
Kind regards, Thomas
Zitat von Christophe Geuzaine <cgeuzaine at uliege.be>:
>> On 5 Aug 2020, at 10:12, t.eschner at dokom.net wrote:
>> Dear all,
>> trying to get acquainted with gmsh/getdp, I stumbled upon two
>> problems that I am not able to resolve.
>> I am trying to model a simple conductive cell with two electrodes,
>> a simple one and a structured one. To me, the results look quite
>> realistic so far (I am still in the stage of checking), with two
>> The first: When I try to calculate the overall current by calling
>> plugin(Integrate) on views slightly above the simple electrode, I
>> get two different results (for the vector view -8,88 and the
>> x-component view -39,9), and neither is close enough to the
>> expected value of -2x(4,94..4,99).
> Be careful with brute-force integration. If you use GetDP would
> recommend using global quantities, which define such integrals in
> the "variationally correct" way: see e.g.
>> The second: The current density field has few spiky values that I
>> do not know how to cure. Their position seems to be constant, the
>> values seem to change with the grid parameters, and it might be
> With a (scalar) potential formulation your current density is
> defined through the gradient, whose accuracy will depend quite
> strongly on the mesh quality. You can give the new "HXT" 3D
> algorithm a try, whose optimizer produces slightly better elements,
> and see if this improves things.
>> Please, have a look and give me a hint on how to correct/proceed. Thank you.
>> Kind regards, Thomas
>> gmsh mailing list
>> gmsh at onelab.info
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer
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