[ThatHimalayanGuy]

Hi all,
I am trying to model a free surface flow problem for a small hydropower plant. The doamin of the problem looks like following when clipped in half (domain is symmetrical):
domain.jpg


The initial water surface levels are 2.5 m upstream side (F 72 -13.4794 8.25 0 5 2.5) and -5 m downstream side (F 72 8.25 16.5206 0 5 -5):
initial_WSL.PNG


The inflow rate is fixed at 9 m3/s (W 10 9), upstream water level is fixed at 2.5 m (F 61 2.5), the downstream level is guided by the flow rate and expected to reach steady condition.

I have tried multiple combination of discretization methods, numerical solvers, turning on and off initialization, turbulence model, adaptive time stepping on/off and grid spacing (15 cm ~ 850k cells, 10 cm ~ 2.8 million cells). However, I am unable to reach a steady state and the solution blows up after few thousand iterations. I am also unable to get the outflow value equal to inflow.


I have attached the control files for DIveMESH and REEF3D. I would be very grateful if somebody could help me figure out how to fix the problem.


I have attached plots of evolution of flow rate for a case without turbullence modelling and fixed time stepping. But the evolution for any other case is similar to this. FlowRate_evolution.PNG


Thank you in advance.

-Rabs