Search found 100 matches

by spacedout
18 Jun 2021, 19:04
Forum: General
Topic: Unstable PDE's
Replies: 0
Views: 34

Unstable PDE's

Hello I created a new thread since the name is more suitable than the previous thread I started on ModelPDE. I am trying to find out where the problem arises with my plasma physics equations. So for all solvers I replaced Linear System Solver = Iterative by Linear System Solver = Direct and for all ...
by spacedout
16 Jun 2021, 20:48
Forum: General
Topic: Can ModelPDE.F90 handle higher order finite elements ?
Replies: 6
Views: 161

Re: Can ModelPDE.F90 handle higher order finite elements ?

Belated thanks What triggered my interest in ModelPDE was the message error system diverges over maximum tolerance in either HeatSolver or StatElecSolver whether I use mpi or not (and the faster the flow, the quicker the divergence happens). So, using ModelPDE as a template, I was thinking of solvin...
by spacedout
03 Jun 2021, 00:37
Forum: General
Topic: Can ModelPDE.F90 handle higher order finite elements ?
Replies: 6
Views: 161

Re: Can ModelPDE.F90 handle higher order finite elements ?

Thank you but what about those keywords Stabilize and Bubbles which are described under some models in the models manual ?
Yours truly
by spacedout
01 Jun 2021, 18:14
Forum: General
Topic: Can ModelPDE.F90 handle higher order finite elements ?
Replies: 6
Views: 161

Can ModelPDE.F90 handle higher order finite elements ?

Hi

I know it was written for educational purposes only but can it deal with the sort of FEM I read about in appendices E, F and G of the Elmer Solver manual ? I mean, without actually ignoring keywords in myfile.sif that would be related to those topics.

Regards, Marc
by spacedout
12 Apr 2021, 05:25
Forum: General
Topic: on areas and volumes of mesh elements
Replies: 4
Views: 498

Re: on areas and volumes of mesh elements

I used ElmerGrid to create a rectangular 200 x 400 mesh where each cell is a square. File mesh.elements shows that each element is of type 404 and has 4 corner nodes. The area of each cell .00001 meters x .00001 meters = 1e-10 square meters but a print out of detJ from detJ = ElementSize(CurrentElem...
by spacedout
08 Apr 2021, 04:49
Forum: General
Topic: on areas and volumes of mesh elements
Replies: 4
Views: 498

Re: on areas and volumes of mesh elements

Good evening I was just thinking of taking the average of all values of a field variable at the nodes of an element. multiply it by the volume of that element and then sum those contributions from each element. It does not matter whether the dimension of each element is given by DIM = CoordinateSyst...
by spacedout
05 Apr 2021, 19:00
Forum: General
Topic: on areas and volumes of mesh elements
Replies: 4
Views: 498

on areas and volumes of mesh elements

Hi I'm integrating a function over the mesh which therefore requires the knowledge of the element's volume. I found out function elementsize under the online Elmer documentation. Yet its description is bizarre: "Returns just the size of the element at its center" ....... To me, the size of...
by spacedout
28 Mar 2021, 20:53
Forum: General
Topic: Mulling over mpi and per element calculations
Replies: 3
Views: 412

Re: Mulling over mpi and per element calculations

I didn't me to offend anybody. I was just hoping to get a confirmation of my suspicion that the major computational cost in ElmerSolver is by far the solution of Ax = b which itself can be iterated several times in the non linear case. The mere assignment of source variables is insignificant by comp...
by spacedout
25 Mar 2021, 18:33
Forum: General
Topic: Mulling over mpi and per element calculations
Replies: 3
Views: 412

Mulling over mpi and per element calculations

Hi everybody Since I now understand that all processors keep a separate copy of the data space as well, I realize they will duplicate assignments on field variables in all existing Elmer solvers in the manner: DO t=1,Solver % NumberOfActiveElements ! get element info Element => GetActiveElement(t) n...
by spacedout
24 Mar 2021, 18:17
Forum: General
Topic: ElmerSolver_mpi stuck in a loop
Replies: 17
Views: 1381

Re: ElmerSolver_mpi stuck in a loop

In the same spirit, I found this on StackOverFlow: QUOTE MPI array syncronization Asked 11 years, 5 months ago Each of your two MPI tasks is working on a different copy of the array. You need to explicitly merge the two arrays using something like MPI_Send() and MPI_Recv() or one of the more complex...