I’ve been trying to simulate the determined released by a co2 cannister within a few seconds of it being punctured by a hole of a 1mm diameter. To do this I tried making a transient compressible simulation, which I would use to determine the exhaust velocity, density and gas pressure at the exhaust.
I tried using two methods. One was an internal flow simulation, where I created an internal flow region within the co2 cannister, and created a pressure inlet-outlet at the puncture hole, and set the initial pressure of the co2 inside the cannister to 60bar. I also made the walls of the cannister a no slip wall with an external wall derived heat flux.
I also tried doing an external flow thing, where I simulated the co2 cannisters puncture hole as a pressure inlet into an external flow region, with the inlet pressure being 60 bar and the initial pressure of the external region being atmospheric. I made the walls of the canister adiabatic, and I made the edges of the external flow region pressure outlets.
Both times, I got the same error, which is that the simulation diverged. I tried increasing relaxation factors, my number of correctors, and I made sure my mesh was high quality. None of that stuff worked. What could be the issue?