DrAmine
Ansys Employee

Just provide the density at outside (corresponding to what you set at pressure outlet: temperature and mass fraction) as the operating density. (Hint: Initialize from Outlet, min/max/avg of the density and use it as operating density). Aslo check if the time steps where the "overshoots" are observed are fully converged and if any strong reversal flow is occuring. 

 

I think the quality of the results is already good. Just check depth of convergence and finalize if you all is behaving as it should! ( Which EOS are you using for CO2 and Ethanol?)