[theindianlel]

Hello!

I am currently working on my masterthesis in Aeroacoustics of Airfoil. For now, I am running an LES Simulation(WALE Subgrid Scale model) of a flat plate with tripping. The results seem to be laminar before and after tripping (see fig, there is also a comparison between RANS and LES Simulation). I used a Tripping Geometry (triangle with base 0.2mm and heigth 0.4mm) at x=4cm (calculated from Rex = 1e5 for transition on flatplate). My surface mesh is NOT highly resolved. My y+ is ~1 and x+ ~100 (LES requires x+<= 40). I used a coarser surface mesh as students before me had good enough results with x+ ~100.

I am not sure how I have to go forward now. I have following ideas

1. Critical Reynolds number for flow over Flat Plate is around 5e5. That could be the problem.
2. Refine surface mesh and try.
3. I could not find any relavent literature for deciding on the trip geometry. If you could point me towards proper literature or suggest me a way to get the right geometry, I would be thankful!

My masterthesis duration is limited and it would save me some time if you could shed some light on where the problem could be and why the flow is not transitioning.

Thanks!

PS: I plotted Wall Shear Stress and not skin friction coefficient because I forgot to time average the skin friction coefficeint in my simulation, and only averaged wall shear stress. For theoretical values, I calculated the wall shear stress from the theoretical skin friction coefficient equation and used it for the plots.