[Fluent_User99]

Hello,
I am trying to simulate a 2D transient flow in supersonic nozzle (with present shock wave). The inlet pressure is 10bar (1 000 000 Pa) and the outlet pressure is only 1 Pa. I am using density based solver and inviscid model. Geometry and mesh is in the attachement.

It seems that Fluent (version 2020R1) is having problem initializing the solution. Since I need to see how the flow develops in time I believe it is necessary to set initial values from the outlet (1 Pa everywhere in the flow domain). For the same reason it is also not possible to initialize the simulation with values from steady simulation or use a hybrid initialization.
To get a solution that does not totally diverge I need to choose a time step much smaller than the one that corresponds to recommended value according to fluent manual (delta t = typ. cell size/ velocity – this is in my case about 1e-9 s). Even by choosing time step 1e-13 s I do not get a converged solution.

I already tried using adaptive time step, mass flow rate inlet/outlet and dynamic mesh but nothing helped.

Does anyone have an idea how to fix this?