Modelling of an Axial Piston Pump

I'm trying to simulate an axial piston pump. There is moving and rotating mesh (pistons). I am trying to get the flow and leakage characteristics. I have given pressure inlet and outlet boundary condition. The inlet has a pressure of 4 bar ( the fluid comes from a tank with a pressure of 4 bar ) and the outlet has atmospheric pressure condition. The Mach number is 0.116, so the simulation is incompressible. The inlet pressure does not have supersonic pressure.

After running the simulation, I am seeing that the outlet pressure is lesser than the inlet pressure. Shouldn't the outlet pressure be greater than the inlet pressure since the pistons are compressing the fluid ? I need to get an outlet pressure of 110 bar to 120 bar.

What is it that I am doing wrong ?


  • KremellaKremella Admin
    edited October 14

    Hi @shrav007

    Apologies for the delayed response. We seem to have missed your post.

    Do you have a flow going from inlet to outlet? Also, it seems that you are specifying an inlet pressure of 4 bar and an outlet pressure of 1 atmospheric pressure (~ 1 bar). This is probably the reason why you have a larger inlet pressure compared to the outlet. Again, I'm not 100% sure of your geometry. Based on what I'm reading, the reason why you are seeing a higher inlet pressure compared to the outlet is because of your boundary conditions.

    I hope this answers your question.

    Thank you.


  • shrav007shrav007 Member
    edited October 15

    Thanks for your reply.

    My flow is going from inlet to outlet. The images are given below.

    Do I have to specify 120 bar at outlet?

    I have also given a zip file containing the motion animation of the Axial Piston Pump obtained from result.

  • To be honest, it depends on what your end modeling goal is? Are you attempting to model the flow inside this pump to understand the performance? Then, I'd try to use pressure inlet and mass flow outlet boundary condition.

    Please have a look at the following YouTube video which goes into the details of how to set-up such a problem. Yes, the pump is different and the performance would also be different. However, you should be able to borrow a few modeling elements from here for your simulation.

    I hope this helps.



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