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Boundary condition problem for counter-current multiphase flows

    • ariyan zare


      I'm working on a project to model CO2 capture inside a column where gases and liquids flow in opposite directions. There is an issue to define boundary conditions for differet phases at the same locations, and I've found that many others have faced the same problem.

      Some researchers have suggested solutions, but not all of them work for my specific model.

      One idea was to give a negative velocity to the liquid inlet at the bottom while giving the gas a positive one at that position. However, it does not make sense when considering velocity inlet for liquid at the top! 

      Another solution might be considering pressure outlet or pressure inlet for both boundaries, but we cannot define another condition for the other phase!

      One paper proposed using a "velocity inlet" and "pressure outlet" for the gas phase and adding source terms for liquid generation and elimination within the domain, right before and after a porous zone, for the liquid phase.

      I'm currently needing recommendations to overcome the challenge I'm facing in my CO2 capture modeling project.


    • Ahmed Hussien


      Defining both an inlet and an outlet on the same patch is not possible. To resolve this, one option is to split the top surface into two patches. For instance, you can create a smaller circle in the center with the liquid inlet, surrounded by a gas outlet. However, to implement this, you should know the location of the liquid inlet on the top surface. Similarly, you can apply the same approach to the lower surface by creating two patches for the gas inlet and liquid outlet. 

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