Convergence in AcuSolve

Hello expert,

I'm using AcuSolve to simulate an internal flow in HVAC system.

The inlet speed is very high (25m/s).

I'm having problem with the convergence of solution, especially with Eddy Viscosity ratio.

Below is my residual ratio plot:

Usually, my calculation converge around 40 time steps.

However, for this simulation, the result always look as above, couldn't achieve congerence with eddy viscosity despite of many mesh refinement.

My question is: if i only concern about the pressure & velocity result, is the velocity & pressure result reliable?

Thank you!