seeta gunti
Ansys Employee

For open channel, time step size of 0.1 is bit coarse. May I know how can you calculate the time step size? You need to calculate the time step based on your cell velocity and minimum cell size. As Satyap mentioned, you need to run the steady case and initialize the data as initial guess to transient case. I would recommend to reduce the time step size and continue the run. Your residuals may come down.

Apart from the residuals, you can add few monitors at the interested regions which will help us to know more about the health of the case whether it is running in right direction or not.