AcuSolve Multiphase simulation

Emanuel_22552
Emanuel_22552 Altair Community Member
edited October 2020 in Community Q&A

Hi there! 

I am trying to simulate a flow of humid air running through an helical pipe. As the air flows, it gets cooled from a negative heat flux on the walls of the pipe.

Any thoughts on how can I approach this problem? Currently, I am not able to run the simulation because I get an error 'Negative absolute pressure for humid air'. 

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Answers

  • acupro
    acupro
    Altair Employee
    edited November 2019

    Which physics phenomena are you trying to capture with the simulation?  Can you add the .inp file and .Log file?

  • Emanuel_22552
    Emanuel_22552 Altair Community Member
    edited November 2019

    hi!

    I am trying to simulate the dehumidification of the air passing through the pipe. Right now I am trying to impose a low temperature on the walls that should easily condensate the water. 

    Unable to find an attachment - read this blog

  • ydigit
    ydigit
    Altair Employee
    edited December 2019

    There are several issues with your setup. 

    Why do you have a mesh motion with ALE? I guess that was unintentional. 

    Also any reason for the pressure offset? 

     

    Try running with these two adjustments (no mesh motion and no pressure offset) and report if it works... 

     

     

  • Emanuel_22552
    Emanuel_22552 Altair Community Member
    edited December 2019

    I changed the pressure offset and then switched the fluid to laminar instead of turbulent. Now it seems that it works.

    My reasons to use a moving mesh is because I would like to simulate the centrifugal force that comes from the fluid passing through the helical tube.

    I am adding the .inp file and the .log, let me know if my approach is wrong.. thanks!

    Unable to find an attachment - read this blog

  • ydigit
    ydigit
    Altair Employee
    edited December 2019

    Why are you using the pressure offset in the first case? I would remove it, unless you know why you introducing it. Also the current value of 10135 seems really odd (assuming you meant it 101325 = 1bar?). 

     

    Keep turbulence (default SA model) on, as that generally helps with convergence. 

    Mesh motion is needed when there is some explicit movement of a part (say FSI or rotating fan or flexible body). In your case I do not see a reason to enable mesh motion.