Convergence
 

hi, i'm study on external flow (water flow in sand domain).

However, from the residual plot shows that the flow is oscillating and it seem like could not be converge.

So, have anyone can help me on the convergence? If my condition is transient state, and could not reach steady state, can it possible converge?? If can not converge, when does i need to take as my final solution?

I set my boundary condition as below:

inlet : (mixture) gauge pressure= 9 atm, total gauge pressure 1 atm
(water)turbulent intensity= 3.5%, turbulent viscosity ratio= 5

outlet:(mixture) pressure= 1atm
(water)turbulent intensity= 1%, turbulent viscosity ratio= 5

I set my time step size=0.005, and number of time step= 20