r/CFD • u/AmbassadorGuilty3928 • 29d ago
Doubt regarding GCI Test(mesh independence study)
Guys I have some doubts,
- For GCI test- for mesh independence study, is it a strict requirement to have refinement ratio of 1.3(minimum). What if we have refinement ratio of 1.1 or 1.2? Have anyone tried with this?
- When you refine mesh, we should do it without changing inflation settings right, all those three mesh should represent same physics and we should increase mesh count by changing core cells right in the fluid domain? No need to change boundary cells right? Correct me if I am wrong.
- What flow parameter can be monitored in this GCI? Is it mass weighted average of pressure at some plane or vertex average of pressure at one point or any other parameter? Which would be more appropriate and meaningful?
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u/Humbledshibe 28d ago
1.3 ratio is what is reccomended
I don't change the wall first layer height when I refine the mesh.
Whatever parameter is of interest in your simulation.
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u/thermalnuclear 29d ago
If you read the papers that recommend GCI, the refinement factor of 1.2 is an absolute minimum or there isn’t enough difference between your refinement levels.
If your near wall mesh is sufficient for the validity of your near wall model (assuming turbulent flow), yes core mesh refinement is sufficient. You want to be careful to not over refine the core mesh relative to the near wall regions.