jjn9128 wrote: ↑
Mon Sep 11, 2017 3:32 pm
Dipesh1995 wrote: ↑
Mon Sep 11, 2017 1:27 pm
That's the best I could do. Click on the video for it play in higher resolution if viewing on a PC. Vortex core collapse starts towards the start of rear wheel wheel so it looks like its the wheel wake that is causing it? Although, this wasn't happening before.
Very good! That's what I was after, it would be good to fix your data contour levels so the colour doesn't change slide-to-slide.
That was my first inclination too - the vortex is pulling low velocity flow from the wheel wake inboard to circulate, so it is suddenly losing angular momentum and the core is collapsing. I would still look at total pressure rather than velocity in your slices as the vortex core should show as Cpo<0.
Why it is now happening when it was not before is a puzzle. Is there anything different about this case? have you changed the mesh, the boundary conditions, averaging interval, solver type?? You said there is a difference with what you are using at home vs at uni? I'm clutching at straws here.... 2 identical cases should produce the same result in CFD.
The mesh is the same, the boundary conditions are the same, averaging interval is untouched and the solver is the same so I don't know what has happened. The general flow field apart from the Y250 is approximately the same. I made some minor changes to the wing around the tunnel vortex serrations and the leading two elements of the wing but none of those parts don't really influence the Y250. The vortex leaving the inboard tips is the same. I have STAR 11 at home and STAR 12 at Uni so I can't view STAR 12 simulations at home but that shouldn't influence the simulation results.
I suspect that if the model had bargeboards, this issue would disappear as wheel wake would be pushed outboards although so would the Y250, honestly, I don't really know whether it would solve it. I'm at 8.5 million cells just with this model so its not really feasible running the simulation with them as I would have to run with some of the chassis and bits of the floor and splitter to get a representative flow field for the barge boards.
My biggest issue at the moment is the excessive (I think) downforce I'm getting. I never thought I'd be saying that when I first started simulating wings. I reduced the blockage ratio to 1.28% from 3.36% today for the computational domain (the frontal area of the half-model is 0.32 m^2 and the inlet area of the domain is 25 m^2) hoping that I would get a reasonable reduction in downforce but that hasn't been the case. Downforce is now 3764 N and drag is 630 N for the half-wing so the numbers for the full wing are 7528 N and 1260 N which is again substantial. The problem is that I don't what F1 front wings generate in numbers. I've seen several estimations online ranging from 400 to 600 kg for cars that are more than a decade old so I don't really know. Even the two-element half-wing tested to get the mesh correct was generating 3500 N in half-wing form so 7000 N in total. If I am setting something wrong, I really don't know what