Fluids

Fluids

Open Channel Flow – different velocity results using different boundary conditions

    • Fbsl
      Subscriber

      Hello,


      So, I am running a VoF model in Fluent with two different sets of boundary conditions. It is an open channel flow with two phases (water and air), and the turbulence model is k-omega.


      I created a report at a point near the inlet and another one near the outlet to monitor the flow velocity and, once I finished running the models, I noticed that the velocities for the same point were different.


      For example:


      Case 1:

      inlet bc: pressure-inlet

      outlet bc: pressure-outlet

      Velocity x at the point near the inlet:

    • Rob
      Ansys Employee
      It'll also depend on what the boundary conditions are set at. Ie are you comparing like with like? Mesh resolution and convergence will play a part too, and the mass flow plot looks a bit "angular" so how well converged was each time step?
    • Fbsl
      Subscriber
      the mesh is the same, the mass flow plot that I posted isn't converged yet, but it didn't change much...
      I want to compare the two boundary conditions, all others parameters are the same, only thing I changed was the inlet boundary condition
    • DrAmine
      Ansys Employee
      Please also check if your pressure inlet input does correspond to what you expect as your input does have dynsmic pressure part (motion) and hydrostatic part.
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