External inviscid flow
I modeled inviscid incompressible external flow around a cylinder with symmetric BC but the velocity or pressure field are not symmetric despite of good convergence. Any idea is appriciated.
What did you do with the viscous terms? An inviscid (Stokes Flow) solution should be symmetric as Re = 0.
Also, define "good" convergence. Floating point error may also make solutions look different to what you might have expected, but not by much.
Thanks ! I used the inviscid option of Fluent. The simulation converged for residuals as small as 1.e-7 but the solution was considerably asymmetric (?) with some recirculation behind the sphere.
Later I changed the pressure discritization from Standard to PRESTO and got much better results. Still not quite symmetric but much better than standard discritization. You may take a look.
Btw, I am solving the Eulair equation (viscosity=0) rather than Stokes flow(viscosity=infinity). In the Eulair equation, the pressure and velocity components all must be symmetric (v is anti-symmetric) at the both side of the cylinder. The Same for velocity components in Stokes flow. But pressure contours must be asymmetric in the Stokes flow !
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