Convergence problem in mixing chamber

SG

Hello everyone.

I have a convergence problem in a mixing chamber. flow is injected into chamber from a big inlet port and 4 small inlet ports.(Inlet B.C. = 40, 30, 20, 10 bar) each of injected flows are merged in mixing chamber and discharged into a discharging nozzle.(Outlet B.C. = 1atm)

In case of low pressure inlet condition(10bar), simulation was well converged with any mesh size and turbulence models. In case of high pressure inlet condition(40,30bar), however, continuity, k and epsilon are diverged.(different mesh size and turbulence models)

Although I changed pressure inlet condition to mass flow rate inlet condition, simulation result was diverged.

How can i solve this problem?

Thank you in advance.