Force Magnitude too high

Hello everyone,

I am currently having an issue with the magnitude of the forces in DualSPHysics...

The units in the xml file are correct and my geometry seems to have correct dimensions when looking at it in paraview. But the forces are 10^12 off !! As if DualSPHysics was multiplying the length in volume and acceleration by 10^3 when computing rho x Volume x acceleration.

Do you have any ideo of what could cause the problem ?

Thanks in advance,

Alextoche

PS : attached is my xml (boat dragged in water with initial speed 30m/s and 1g acceleration) and a plot of the forces


Comments

  • Please check sthg very strange in Forces.PNG... which is that time use "." for decimal separation but you have "," in the force...

    Regards

  • edited May 2020

    Thanks for the answer,

    You are right !! Excel did a mistake when converting the file... the force values are ok when looking at the txt file.

    I have an other problem tho... when dropping the boat above water with initial speed 1m/s downwards and density 166kg/m^3

    (I am using the v5) it bounces. It thought that it was due to the forces but now that this problem is solved...

    Any idea ?

  • You are plotting sthg in the wrong way

    Since the shape of the boat is in the fluid representation while your boat is not moving accordingly.

    Note that it can not bounce since you have define the boat as a moving boundary and you are imposing the motion, so the boat has to move as you want.

    Please share here the execution parameters you use during post-processing for IsoSurface and BoundaryVTK?


    Regards

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