[mvee]

The hydraulic transient problem in a tail race channel of a hydro power plant is of open free surface problem i.e., the tailrace is partially filled with water and remaining portion is opened to atmosphere. The water enters the tail race channel from multiple draft tubes and leaves into a river through a single continuous exit. The exit area is less compared to the inlet and so the mass of water gets accumulated in the tail race channel due to which the water free surface level rises to some extent and after some time a steady state is reached and free surface of water is maintained through out the tail race channel. This level is well above the exit as well as the inlets.
The model of the tail race channel is prepared in gambit. The boundary conditions are velocity inlets and pressure outlet. The doubt is how can the top surface be defined? Is there any option for defining the top as open i.e. free to atmosphere?

Any reply or query is of important.


Reply
mahesh

[zhaopeng]

it is a open channel flow problem,you can define the top as pressue inlet.