Learning Forum

[Ruben Joosten]

I'm currently trying to simulate flow past the hull of a boat to calculate the drag coefficient. 

However, I have a pressure inlet and outlet such that the water level remains the same. However, as you can see in the image the water flows from the inlet and then causes a backflow and doesn't create the free stream flow I would like. How can I change my boundary conditions or setup to ensure I achieve the free stream I would like. 

Some information on my setup can be found below:

-VOF, multiphase (water and air)

-Open channel flow, (no wave BC, with wave BC there was no change), implicit body force

-K-Omega SST turbulence model.

-Hull is fixed (preferably want to change it to moving mesh fixed on some axes as a bobbing boat on the water)

-Pressure inlet and outlet (Velocity inlet I achieved the same results)

-Inlet is set to 1.5m/s at a level 0.25 m (waterline)

-Outlet is set to 0.25m,

-Wall is no slip

If more information is required, let me know. 

Thank you for taking the time to read my post,

 

[Rob]

If you look at the domain scale what do you get? Is gravity on? 

[Ruben Joosten]

Hello Rob, thank you for responding.
I'm not entirely sure what you mean by domain scale. The domain is of size 10x10x28 m and the boat is 6m.
Gravity is on and is -9.81. 

[Rob]

OK, and what height is the free surface? You mention putting in 0.25m but is that the middle?