Dear Niki, If my understanding is right. It seems that for dual-time AC method in pyFR, there are difficulties on the convergence of the diffusion term. Based on my simulations, the pressure residual of the pseudo convergence file increases with the intensity of the flow diffusion. Very low pressure residual (less than 1) only happens when the flow is only in convection dominance but not much diffusion, which makes the flow behave laminar. When the turbulence intensity of the flow occurs, the pressure residual is no longer small (around 10) and shows a strong stiffness (decreases linearly with very small slope). When the turbulence intensity of the flow increases the pressure residual increases (larger than 10) and still shows a very strong stiffness. So the pressure residual in pyFR is more like an indicator of diffusion intensity but not convergence.
So I don't quite understand how do you converge and meet the mass conservation (div u = 0) in AC method? It seems that pyFR has difficulties on holding mass conservation in turbulence. Have you ever tested the AC solver on diffusion equations? Does it really show small residuals? As you said "The pressure residual (div u), which is more stiff to converge than velocity residuals". According to you, "is kind of an indicator how far the pseudo waves which distribute the pressure have travelled". Actually, I don't know the connection between the pseudo waves and mass conservation. In your cases shown above, you have really small pressure residual. How is the turbulence intensity in your cases? Is the flow behaving in chaos or more laminar flow? Best regards, Will -- You received this message because you are subscribed to the Google Groups "PyFR Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. Visit this group at https://groups.google.com/group/pyfrmailinglist. For more options, visit https://groups.google.com/d/optout.
