|
[Sponsors] |
Free surface sensitivity - drag coefficient & mesh sizes |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
December 28, 2017, 13:14 |
Free surface sensitivity - drag coefficient & mesh sizes
|
#1 |
New Member
Join Date: Dec 2017
Posts: 2
Rep Power: 0 |
Hello,
I'm calibrating the free surface in a river channel for different 3D triangular meshes. I'm using the drag coefficient (CD) to do so. I notice that on my rough mesh my free surface calibrates with a realistic CD, however using my refined meshes the free surface is a lot lower and is also less sensitive to changes in CD. This results in a calibrated free surface for my refined meshes with a high CD above what is realistic. I expected there to be differences in elevation between different meshes as the model became independent, however the free surface seems to be lower and less accurate for the refined mesh. How does the changes in mesh size affect the sensitivity of the free surface to changes in the CD? Why would the free surface be lower for the refined mesh? The geometry is very similar for the rough and refined meshes, with the largest differences being 0.01m in some of the pools. The boundary conditions are unchanged. Testing the solvers doesn't change the elevation, rather than how "smooth" it is. Neither does changing the boundary conditions for the free surface. I'm struggling to think what is at play here and I'm wondering if there's some theory behind free surface simulation I've overlooked? Could it be due to the time-step? I'm using Telemac 3D (v7p2r3). Many thanks. |
|
May 15, 2023, 12:53 |
|
#2 |
New Member
Mariana Marin
Join Date: May 2023
Posts: 2
Rep Power: 0 |
if you change your time-step as they refine the mesh size? Remember Courant's theory.
|
|
Tags |
channel, drag, free surface, mesh size, telemac |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
y+ = 1 boundary layer mesh with snappyHexMesh | Arzed23 | OpenFOAM Running, Solving & CFD | 6 | November 23, 2022 16:15 |
[snappyHexMesh] Mesh around ship with appropriate free surface refinement | Hannes_Kiel | OpenFOAM Meshing & Mesh Conversion | 46 | October 4, 2019 08:28 |
Mesh Indepedence Test in Ahmed, Drag Coefficient still going down | treviusss | FLUENT | 0 | December 6, 2017 09:38 |
[snappyHexMesh] No layers in a small gap | bobburnquist | OpenFOAM Meshing & Mesh Conversion | 6 | August 26, 2015 10:38 |
[snappyHexMesh] snappyHexMesh won't work - zeros everywhere! | sc298 | OpenFOAM Meshing & Mesh Conversion | 2 | March 27, 2011 22:11 |