|
[Sponsors] |
|
February 19, 2019, 06:14 |
Adaptive mesh refinement operation
|
#1 |
New Member
Join Date: Feb 2019
Posts: 23
Rep Power: 7 |
Hello all,
When testing the damBreak tutorial applying adaptive mesh refinement it seems the mesh it's not correct, i mean, there are octrees but something weird too in the transition zone to the unrefined mesh part (see image attached). I've been looking to the Tobias Holzmann case http://voluntary.holzmann-cfd.de/ope...ment-pseudo-2d in wich the adaptative mesh refinement is correct. Maybe it has something to do with the snappyHexMesh utility he uses but i guess it should work using blockMesh too. Hope you can help me because i haven't found anything about this, Thank you. |
|
February 19, 2019, 06:25 |
|
#2 |
Senior Member
anonymous
Join Date: Jan 2016
Posts: 416
Rep Power: 14 |
Hi!
It is correct. Paraview is decomposing polyhedral elements into tets. You have to switch the "decomposePolyhedron", or "use VTK polyhedron" or something like that button depending on your paraview version. You can find somewhere in the Properties panel (under the apply button) when you import your case into paraview. And also if you create a slice you have to set "triangulate" to off. Or your silce will be triangulated and you will see the same. |
|
February 19, 2019, 08:00 |
|
#3 |
New Member
Join Date: Feb 2019
Posts: 23
Rep Power: 7 |
Thank you!
Just to be sure: i understand then that this is only a paraView issue, i mean, openFOAM makes the refinement octree, true? But if i type checkMesh for example for t=0.14s : Code:
Time = 0.14 Mesh stats points: 120660 faces: 326739 internal faces: 317286 cells: 103181 faces per cell: 6.2417 boundary patches: 2 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 95312 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 7869 Breakdown of polyhedra by number of faces: faces number of cells 6 1019 9 5594 12 1050 15 205 18 1 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 atmosphere 1024 1089 ok (non-closed singly connected) walls 8429 8835 ok (non-closed singly connected) Checking geometry... Overall domain bounding box (0 0 0) (1 1 1) Mesh has 3 geometric (non-empty/wedge) directions (1 1 1) Mesh has 3 solution (non-empty) directions (1 1 1) Boundary openness (-3.61401e-20 -2.84603e-19 -4.51751e-19) OK. Max cell openness = 2.22045e-16 OK. Max aspect ratio = 1 OK. Minimum face area = 6.10352e-05. Maximum face area = 0.000976562. Face area magnitudes OK. Min volume = 4.76837e-07. Max volume = 3.05176e-05. Total volume = 1. Cell volumes OK. Mesh non-orthogonality Max: 25.2394 average: 8.11163 Non-orthogonality check OK. Face pyramids OK. Max skewness = 0.333333 OK. Coupled point location match (average 0) OK. Mesh OK. Thank you again |
|
February 19, 2019, 08:17 |
|
#4 |
Senior Member
anonymous
Join Date: Jan 2016
Posts: 416
Rep Power: 14 |
They are diferent. hexa is a "cube", with 6 sides, 8 vertices.
Polyhedra is an n sided volume. The refinemen engine is using a "splitHex" method, where you split the hex into 8 hexes. But when you have 2 hexa elements near each other, and you refine only one of them (transition zone), you have to split one face of the "uncutted" element into 4 faces. in 2D: Code:
__ __ __ __ __ __ __ __ | | | -> | |__|__| |__ __|__ __| |__ __|__|__| |
|
February 19, 2019, 08:33 |
|
#5 |
New Member
Join Date: Feb 2019
Posts: 23
Rep Power: 7 |
Thank you very much, it was really helpfull!
|
|
February 19, 2019, 08:39 |
|
#6 |
Senior Member
anonymous
Join Date: Jan 2016
Posts: 416
Rep Power: 14 |
You are welcome!
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
[snappyHexMesh] snappyHexMesh sticking point | natty_king | OpenFOAM Meshing & Mesh Conversion | 11 | February 20, 2024 10:12 |
[snappyHexMesh] Error snappyhexmesh - Multiple outside loops | avinashjagdale | OpenFOAM Meshing & Mesh Conversion | 53 | March 8, 2019 10:42 |
[snappyHexMesh] Snappy Hex Mesh - issue with smoothness of the model edges | olek.warc | OpenFOAM Meshing & Mesh Conversion | 1 | August 31, 2018 12:31 |
[snappyHexMesh] SnappyHexMesh for internal Flow | vishwa | OpenFOAM Meshing & Mesh Conversion | 24 | June 27, 2016 09:54 |
fluent add additional zones for the mesh file | SSL | FLUENT | 2 | January 26, 2008 12:55 |