[blockMesh] Courant in axisymmetric simulations

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 December 18, 2018, 10:49 Courant in axisymmetric simulations #1 New Member   Arne Join Date: Dec 2018 Posts: 19 Rep Power: 6 Hi foamers I am currently trying to simulate an axis-symmetrical set-up using wedge. Because of the wedge-like shape, some cells become very small. I tried to solve this using the simpleGrading which makes the cells near the axis longer (in r-direction) than the cells further away from the axis. However, I still get very long calculation times. Is there any other method which I can apply to reduce the calculation time? I am using a wedge of 1°, so the cells are also very thin. I could increase this to 5 degrees, but I am not sure whether: - the calculation time will decrease significantly? - this has any influence on the accuracy of the simulation? Thank you in advance Best regards Arne

 March 6, 2019, 03:44 #2 Senior Member   Zander Meiring Join Date: Jul 2018 Posts: 125 Rep Power: 6 Is your mesh 2d, or 3d? What does meshCheck say?

 March 6, 2019, 04:26 #3 New Member   Arne Join Date: Dec 2018 Posts: 19 Rep Power: 6 Hi yambanshee Thank you very much for your reply. My mesh is 2D, which I thought was obligated when using the wedge-boundary conditions? I did not try checkMesh yet, my mesh works since the calculations run, they just run very slowly because of the Courant Number in the cells at the axis. I will try checkMesh immediatly and I will let you know the results. Best regards Arne __________________________________________________ __________________________________________________ ________________________________ EDIT: I just tried checkMesh and he results are below. This mesh was made with blockMesh and had a simpleGrading of (1 1 1). /*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v1806 | | \\ / A nd | Web: www.OpenFOAM.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : v1806 Arch : "LSB;label=32;scalar=64" Exec : checkMesh Date : Mar 06 2019 Time : 09:26:36 Host : "ea10c417" PID : 672 I/O : uncollated Case : /mnt/c/Users/arsimons/Documents/OpenFOAM_local/simulaties/AA_Geometry/Wedge nProcs : 1 trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10) allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 Time = 0 Mesh stats points: 20301 internal points: 0 faces: 40050 internal faces: 19750 cells: 10000 faces per cell: 5.98 boundary patches: 6 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 9800 prisms: 200 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: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology axis 0 0 ok (empty) rightWall 200 402 ok (non-closed singly connected) lowerWall 50 101 ok (non-closed singly connected) atmosphere 50 101 ok (non-closed singly connected) back 10000 10251 ok (non-closed singly connected) front 10000 10251 ok (non-closed singly connected) Checking faceZone topology for multiply connected surfaces... No faceZones found. Checking basic cellZone addressing... No cellZones found. Checking geometry... Overall domain bounding box (0 0 -0.0174) (0.05 0.2 0.0174) Mesh has 2 geometric (non-empty/wedge) directions (1 1 0) Mesh has 3 solution (non-empty) directions (1 1 1) Wedge back with angle 19.1879 degrees Wedge front with angle 19.1879 degrees All edges aligned with or perpendicular to non-empty directions. Boundary openness (7.25056e-14 -3.85576e-18 1.36653e-17) OK. Max cell openness = 2.21273e-16 OK. Max aspect ratio = 2 OK. Minimum face area = 3.48e-07. Maximum face area = 3.48e-05. Face area magnitudes OK. Min volume = 3.48e-10. Max volume = 3.4452e-08. Total volume = 0.000174. Cell volumes OK. Mesh non-orthogonality Max: 0 average: 0 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.869726 OK. Coupled point location match (average 0) OK. Mesh OK. End Last edited by arsimons; March 6, 2019 at 04:29. Reason: additional info

 Tags axis, axis-symmetric, calculation time, wedge