|
[Sponsors] |
![]() |
![]() |
#1 |
New Member
Join Date: Jun 2021
Posts: 8
Rep Power: 5 ![]() |
Hi,
I am currently performing a grid convergency study using StarCCM+. The investigated airfoil is the NACA 63-415 with a chord length of approximately 0.6m. I decided to use an unstructured grid with prism layers. I am still a beginner and I would like to ask you some questions: - I have to refine my grid in the direction normal to the wall (say y-direction). With how many prism layers do you suggest to start? In which way does the number of prism layers influence the accuracy of my results? - I also have to refine the grid in chordwise direction (say x-direction) in order to capture the transition process. In this case, which parameters should I change? - I don't fully understand the meaning of the base size. Can anyone explain it? - How to I display the transition point? I know these are a lot of different questions, but I would be really grateful if someone would answer them. |
|
![]() |
![]() |
![]() |
![]() |
#2 |
Senior Member
Lefteris
Join Date: Oct 2011
Location: UK
Posts: 339
Rep Power: 15 ![]() |
You can use a volume refinement and enable the anisotropic refinement option, that way you can specify different cell sizes in the x, y and z directions.
I suppose the question about the layers will be answered through the mesh sensitivity study. There are a few things to consider such as wall functions, y+, transition from the layers to the volume mesh... Base size is what the words says, the (base) size of the cell. If you were to create a trimmer mesh for example with cells 100% of the base size, you would have all cells with the same size. With trimmer mesh each mesh refinement splits 1 cell into 4 cells. So you do the math. What transition point are you talking about? Are you looking into laminar-turbulent transition?
__________________
Lefteris |
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Join Date: Jun 2021
Posts: 8
Rep Power: 5 ![]() |
Yes. I mean laminar-turbulent transition. I would like to display the exact position where the transition (laminar to turbulent) takes place.
I still do not understad the meaning of the base size. If the airfoil chord is 0.6m and I choose a base size of 0.006m, does it mean that the mesh will have 100 cells in chordwise direction? Last edited by mtheory; June 25, 2021 at 10:42. Reason: Grammar errore |
|
![]() |
![]() |
![]() |
![]() |
#4 | |
Member
Rinia
Join Date: Jan 2018
Posts: 42
Rep Power: 8 ![]() |
Quote:
|
||
![]() |
![]() |
![]() |
Tags |
airfoil 2d, base size, grid convergence study, prism layer, starccm |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
Convergence Study | asda3D | Main CFD Forum | 5 | March 25, 2019 08:18 |
Grid Convergence Index (GCI) for study involving five grids | RobV | Visualization & Post-Processing | 0 | December 30, 2016 06:22 |
[Other] Grid convergence study of adaptive mesh | Blue8655 | OpenFOAM Meshing & Mesh Conversion | 0 | December 9, 2016 21:15 |
[ICEM] Grid Convergence Index study for a hybrid mesh | j_h_86 | ANSYS Meshing & Geometry | 2 | December 6, 2012 11:45 |
Grid Refinement Study - How many cells necessary for accurate results? | ejvikings | FLUENT | 1 | January 22, 2012 00:33 |