|
[Sponsors] |
February 3, 2015, 13:55 |
Negative courant number
|
#1 |
Senior Member
Samuele Z
Join Date: Oct 2009
Location: Mozzate - Co - Italy
Posts: 520
Rep Power: 18 |
Dear All,
I am running a simulation using pimplefoam and something strange happens: I get a negativa courant number, from the very first iteration. Code:
Create time Create mesh for time = 0 Reading field p Reading field U --> FOAM Warning : From function Field<Type>::Field(const word& keyword, const dictionary&, const label) in file /home/szampini/OpenFOAM/OpenFOAM-2.3.1/src/OpenFOAM/lnInclude/Field.C at line 318 Reading "/home/szampini/Documenti/Afros/CFDSimulations/testRTM/0/U.boundaryField.inlet" from line 29 to line 9 expected keyword 'uniform' or 'nonuniform', assuming deprecated Field format from Foam version 2.0. Reading/calculating face flux field phi Selecting incompressible transport model Newtonian Selecting turbulence model type laminar No finite volume options present PIMPLE: Operating solver in PISO mode Starting time loop Courant Number mean: -1.68919e-06 max: -0 deltaT = 0.000111111 Time = 0.000111111 smoothSolver: Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 0 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.0219292, No Iterations 1000 smoothSolver: Solving for Uz, Initial Could you have a look at the attached case? Thanks a lot, Samuele |
|
February 3, 2015, 15:01 |
|
#2 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
Blog Entries: 45
Rep Power: 128 |
Quick answer: Incorrect usage of a transient solver, see file "system/fvSchemes":
Code:
ddtSchemes { default steadyState; } |
|
February 4, 2015, 06:03 |
|
#3 |
Senior Member
Samuele Z
Join Date: Oct 2009
Location: Mozzate - Co - Italy
Posts: 520
Rep Power: 18 |
This was for sure an error, but not the only one. I changed the time scheme, but nothing happened.
Any other idea? Thanks, Samuele |
|
February 4, 2015, 12:29 |
|
#4 |
Senior Member
|
Hi Samuele,
I ran your Allrun script except for the pimpleFoam part and after that I ran checkMesh. During blockMesh there is already a warning for negative volumes, which is later confirmed by checkMesh output. I copied that output for you here: Code:
Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 452403 faces: 1041592 internal faces: 734408 cells: 296000 faces per cell: 6 boundary patches: 5 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 296000 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. *Number of regions: 5 The mesh has multiple regions which are not connected by any face. <<Writing region information to "0/cellToRegion" <<Writing region 0 with 18000 cells to cellSet region0 <<Writing region 1 with 30000 cells to cellSet region1 <<Writing region 2 with 200000 cells to cellSet region2 <<Writing region 3 with 30000 cells to cellSet region3 <<Writing region 4 with 18000 cells to cellSet region4 Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology outlet1 592 903 ok (non-closed singly connected) outlet2 592 903 ok (non-closed singly connected) top 101900 103626 ok (non-closed singly connected) walls 204000 205911 ok (non-closed singly connected) inlet 100 121 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (-0.12 0 -0.25) (0.12 0.03 0.25) Mesh (non-empty, non-wedge) directions (1 1 1) Mesh (non-empty) directions (1 1 1) Boundary openness (8.43768e-19 1.05278e-17 -3.86038e-20) OK. ***High aspect ratio cells found, Max aspect ratio: 1e+194, number of cells 296000 <<Writing 296000 cells with high aspect ratio to set highAspectRatioCells Minimum face area = 1e-06. Maximum face area = 1e-06. Face area magnitudes OK. ***Zero or negative cell volume detected. Minimum negative volume: -1e-09, Number of negative volume cells: 296000 <<Writing 296000 zero volume cells to set zeroVolumeCells Mesh non-orthogonality Max: 180 average: 180 ***Number of non-orthogonality errors: 734408. <<Writing 734408 non-orthogonal faces to set nonOrthoFaces ***Error in face pyramids: 1776000 faces are incorrectly oriented. <<Writing 1041592 faces with incorrect orientation to set wrongOrientedFaces Max skewness = 2.5e-06 OK. Coupled point location match (average 0) OK. Failed 4 mesh checks. End Please check your blockMesh setup and make sure you have a valid mesh before running pimpleFoam. Regards, Tom |
|
February 5, 2015, 06:11 |
|
#5 |
Senior Member
Samuele Z
Join Date: Oct 2009
Location: Mozzate - Co - Italy
Posts: 520
Rep Power: 18 |
Got it: solved!
Thanks a lot, Samuele. This was a problem in the blockMeshDict! Samuele |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
AMI speed performance | danny123 | OpenFOAM | 21 | October 24, 2020 04:13 |
[mesh manipulation] Mesh Refinement | Luiz Eduardo Bittencourt Sampaio (Sampaio) | OpenFOAM Meshing & Mesh Conversion | 42 | January 8, 2017 12:55 |
[blockMesh] BlockMeshmergePatchPairs | hjasak | OpenFOAM Meshing & Mesh Conversion | 11 | August 15, 2008 07:36 |
IcoFoam parallel woes | msrinath80 | OpenFOAM Running, Solving & CFD | 9 | July 22, 2007 02:58 |
Could anybody help me see this error and give help | liugx212 | OpenFOAM Running, Solving & CFD | 3 | January 4, 2006 18:07 |