Mfluid element mass repartition :OS-V: 0460 Dynamic Behavior of a Fluid-containing Structure using MFLUID

Insaf Mohamed Rizan
Insaf Mohamed Rizan Altair Community Member
edited February 14 in Community Q&A
I have been using the benchmark model appearing in your guide for some simulations.
OS-V: 0460 Dynamic Behavior of a Fluid-containing Structure using MFLUID
However there are some points that I would like to clarify with your support on these models to get a better understanding of the Mfluid element available on your package.
 
My question is regarding the Mass matrix outpu.Indeed when we simulated we observed that the mass is lower in the Z direction  than the 2 other directions, even when you have a 100% fill.
How is this possible? Is there any theoretical explanation for this ?
 
Thanking you in advance
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Answers

  • Xiaolei
    Xiaolei
    Altair Employee
    edited February 14

    Hi Insaf, 

    Can you let me now how you checked the mass matrix of virtual mass alone? As long as I know OS only supports DMIG for the entire model(structure+MFLUID).

    Can you also check partial filled let's say with a height that is smaller than radius of the cylinder?

     

    Thanks. 

    Xiaolei 

  • Insaf Mohamed Rizan
    Insaf Mohamed Rizan Altair Community Member
    edited February 14
    Xiaolei Song_21874 said:

    Hi Insaf, 

    Can you let me now how you checked the mass matrix of virtual mass alone? As long as I know OS only supports DMIG for the entire model(structure+MFLUID).

    Can you also check partial filled let's say with a height that is smaller than radius of the cylinder?

     

    Thanks. 

    Xiaolei 

    Hello Xiaolei ,
    You can add the following params to get the fluid mass matrix output:

    PARAM,CHECKEL,NO      
    PARAM,EFFMAS,YES
    PARAM,GRDPNT,15969
    PARAM,VMMASS,YES     
    PARAM,VMOPT,1       

    I have tried for different fill levels and you get the result in the output file

     

  • Xiaolei
    Xiaolei
    Altair Employee
    edited February 14
    Insaf Mohamed Rizan said:

    Hello Xiaolei ,
    You can add the following params to get the fluid mass matrix output:

    PARAM,CHECKEL,NO      
    PARAM,EFFMAS,YES
    PARAM,GRDPNT,15969
    PARAM,VMMASS,YES     
    PARAM,VMOPT,1       

    I have tried for different fill levels and you get the result in the output file

     

    I tried with a 25% fill level(the one on the right side), then the pass in P1 and P2 is much smaller. 

    image

    I don't have the formula of this directional mass calculation at hand, but I think this change should make sense. 

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