Compressible Non-Linear Reynolds Equation

Hello to all,

I am trying to solve the Non-Linear Reynolds equation on a rectangular domain with Dirichlet (=-pps) pressure all around.

I create the geometry and the coefficient function for h but have no experience with ngsolve and cant figure hot to do the discretization and initialization properly. Is anyone eager to help me out?

Thank you,
George K

Reynolds.ipynb (12.9 KB)

after doing integration by parts your bf term should look something like this:

a += (h**3/(6*nu) * u * grad(u) * grad(v) - (p * h * CF((U,V)) * grad(v)) * dx

for newton convergence it’s better to set the dirichlet values already on the whole domain and not only on the boundary

Thank you very much Christopher.
I’m one step closer I just have to figure out periodic boundaries now.

you already had the identification correctly in the script. Just wrap the H1 space with a Periodic(H1(…)) and remove the dirichlet from left and right

Thank you that worked!

Hello, I have a follow-up question.

Is it possible to impose a constraint within the iterative process so my result does not go beneath a certain value (eg ambient pressure). This is for cavitation modeling in Journal bearings.

Thank you!