|
[Sponsors] |
May 30, 2017, 08:29 |
fvm::laplacian on a regular tetrahedral mesh
|
#1 |
New Member
Benjamin Kalloch
Join Date: Mar 2016
Posts: 1
Rep Power: 0 |
Hello everyone!
I have a seemingly simple issue for which I cannot find a solution, probably because I am a beginner with OpenFOAM and FVM in general. My test-case: - an ideal capacitor with two infinitely large capacitor plates and a homogeneous conductive medium in between as a steady-state case The Geometry: - box domain 5x5x5m on a regular tetrahedral grid - left and right boundaries of the box have a value of +5/-5 Volts - all other boundaries (top&bottom, front&back) have a zeroGradient BC (see the attached images 'domain_1' & 'domain_2' for a depiction of the geometry and the BCs) domain_1.jpg domain_2.jpg The solver setup: I want to solve the electrical potential between the capacitor plates using the equation Code:
0 = ∇( sigma ∇(ElPot) ) Code:
#include "fvCFD.H" int main( int argc, char *argv[] ) { #include "setRootCase.H" #include "createTime.H" #include "createMesh.H" #include "createFields.H" // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solve( fvm::laplacian( sigma, ElPot) ); ElPot.write(); return(0); } (see image 'expected_result'; aside from the [expected] jumps from one cell to another the value remains the same) expected_result.jpg This works perfectly fine for a hexahedral grid. The issue: However the result is impaired by the structure of the regular tetrahedral grid. Values sampled from a line parallel to the capacitor plates are not the same but slowly decrease. (see image 'calculated_result'; here the values decrease over the sampling-line) calculated_result.jpg As a discretization scheme I use: Code:
divSchemes { default Gauss linear limited 1.0; } laplacianSchemes { laplacian(sigma,ElPot) Gauss linear limited 1.0; } http://www.tfd.chalmers.se/~hani/kur...stPractice.pdf The solver settings are are: Code:
ElPot { solver PCG; preconditioner DIC; tolerance 1e-15; relTol 0; maxIter 50000; }; Is this a inevitable issue with this kind of grid and the way OpenFOAM solves the laplacian or did I miss a vital scheme / setting? How could I solve this issue? Thanks a lot in advance! Last edited by ben_k; June 7, 2017 at 09:52. Reason: For a better referencing, I have inserted the attachements directly into the text. |
|
Tags |
laplacian, tetrahedral mesh |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
[ICEM] 2D hybrid mesh (unstructured mesh highly dependent on structured mesh parameters) | shubham jain | ANSYS Meshing & Geometry | 1 | April 10, 2017 05:03 |
[snappyHexMesh] SnappyHexMesh for internal Flow | vishwa | OpenFOAM Meshing & Mesh Conversion | 24 | June 27, 2016 08:54 |
Problem: tetrahedral mesh and interFoam = bad results ? | querdynamik | OpenFOAM Running, Solving & CFD | 1 | October 10, 2015 14:17 |
ParaView Compilation | jakaranda | OpenFOAM Installation | 3 | October 27, 2008 11:46 |
Icemcfd 11: Loss of mesh from surface mesh option? | Joe | CFX | 2 | March 26, 2007 18:10 |