Dear all, I was trying to run a few cases at a higher Re on PyFR.1.12.1. The first case was a flow over 2d square cylinder at Re=2.2e4 using AC solver. As a start, I initiated the cases with p=1 and a sponge field for 50s, dt = 5e-3 and pseudo dt=2e-4. Everything seemed fine except the pressure res…

There is quite a lot to unpack here, but I’ll try to address some of the points. You say that the forces are ‘unstable’, from what you are saying I’m assuming you mean that there isn’t some nice regular pattern? I don’t have a lot of experience from square cylinders, but with round cylinders, as yo…

Hi Will, Thanks for your kind reply. I have to admit that the case is actually a 3d problem and the loss of accuracy is inevitable. In fact, one reason I set the case in 2D is that I’d like to check my mesh was ok for the problem, so then I could extrude it in 3D with the least calculation cost. Th…

Hi Will, Things are looking up a bit when I ran a 3d simulation with the pressure residual fluctuating around 0.01, smaller than 2d simulations. It should also be noted that the polynomial order in this case was only p1 with a P-multigrids cycle [(1,1),(0,2),(1,3)], the latter showed a strong contr…

I’m glad moving to 3D helped. I have two further points to make about this. The first is that you are running p1. (order=1). DG, and by extension FR, does not have particularly good numerical characteristics at p1. You might want to try upping the order and maybe reducing the mesh resolution a litt…

Question about stability of AC solver at a higher Re

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Question about stability of AC solver at a higher Re

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