[Aijiazi]

I am simulating 3D slender body at high angle of attack. Re=3 million. y+<1. I tried different meshes from course to fine but the problem remains. I am attaching residual picture. Any help is highly appreciated. I am stuck at it for a long time.
residual.jpg

[saihasil]

Use coupled algorithm and make the Courant number as 0.5

[Aijiazi]

Originally Posted by saihasil

Use coupled algorithm and make the Courant number as 0.5

Thank you for your reply Saihasil,
I am using coupled scheme, i tried range of courant number from 5 to 200. But following your suggestion i will try with 0.5 and will let you know the result.

Another thing i want you to know, if I make Y+=30 then the problem goes away. with courant no =20.

but the results not good as it does not capture separation.

[Aijiazi]

i tried that method but still doesnot work.Residuals still increasing

[saihasil]

Originally Posted by Aijiazi

i tried that method but still doesnot work.Residuals still increasing

If the residual is increasing after sometime it may diverge.
So, do the Grid Independence Test
Make the three cases of element size and compare the results.

[Aijiazi]

Originally Posted by saihasil

If the residual is increasing after sometime it may diverge.
So, do the Grid Independence Test
Make the three cases of element size and compare the results.

i,cant complete the solution because wheb the residual increases it says,divergence detected in amg solver.

i seek some suggestion, someone say to calculate time step for this case, but i dont know how to calculate time step.