NACA 0021 Airfoil in Deep Stall - Minimum sized time step rejected

Anh Vu Nguyen

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Sep 4, 2020, 6:02:25 AM9/4/20

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Hello PyFR Community, I'm currently trying to recreate the simulations from the paper of Park, Vincent and Witherden (2017) on a NACA0021 Aerofoil in deep stall.

I am using the provided mesh and configuration file for the p4.ini file and p4_mesh and started with a warmup phase until t=100 with p=1 and Re=27000.

After the warmup phase I changed the parameters to p=4 and Re=270000. However, I am getting a 'minimum sized time step rejected' error at around t=226.

Could you help me and share any information and tips, how I can solve this error?

I attached the configuration file after the warmup phase.

Best regards, Vu

p4_naca.ini

Giorgio Giangaspero

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Sep 8, 2020, 3:15:48 AM9/8/20

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Hi Vu

usually this happens when switching to high-order without enabling anti-aliasing. However, I see in your .ini file that anti-aliasing is indeed enabled in your case.

Did you enable it when you switched to p=4 or later on?

Best

Giorgio

Anh Vu Nguyen

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Sep 8, 2020, 5:34:12 PM9/8/20

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Hey Giorgio,

thanks for the reply. I noticed that I didn't disable anti-aliasing during the warmup period. So it was enabled from the beginning. I'm not sure if that is the reason for the time step error, but I'm currently trying to run it again with anti-aliasing enabled at t=100, when I switched to p=4 and see if it makes any difference.