Learning Forum

[Joseph Echols]

I'm working on a shock tube problem with a helium driver and air driven section and I'm having issues getting a proper solution. The geometry is a simple rectangle and the simulation has worked in the past when I only used air for both the driver and driven sections. I've used a density based, inviscid flow with transient solution with the energy equation turned on. I set the cell boundary zones to be helium and air for the driver and driven sections respectively. I patched the pressures to be 500kPa for the driver and 101.325kPa for the driven. When I run at a time step of 7e-6 I get a solution that doesn't match the theory. I've found a forum post similar to this one with a fix but when I try it, a solution doesn't converge. Maybe I didn't implement the fix properly but I'm not sure how to solve the issue I'm having.

[Rob]

How well converged is the result? How well resolved is the mesh?

[Joseph Echols]

Everything looked good when I was tracking the residuals and the mesh looks fine. I refined the mesh more and the issue hasn't resolved

[Rob]

If you look at the flow speed how long does it take the fastest part to cross one cell?