transient pressure waves in water

marc_ramseymarc_ramsey
I need to simulate transient pressure waves in water. With other software, I've done this using a linear dynamic analysis, intended for solid materials, but set the shear modulus of the material an order of magnitude below the young's modulus in order to approximate the behavior of water (i.e. make the shear waves insignificant compared to the longitudinal waves).

Doing this implies a poisson ratio >> 0.5. Mecway internal solver will not let me do this, nor will CCX.

I understand that poisson > 0.5 does not make sense for a solid analysis. But it actually does make sense (I think) for modelling linear pressure disturbances within a bounded volume of liquid-like material.

Any ideas how to achieve my objective?

Thanks!

Marc

Comments

  • VictorVictor
    I don't think it's possible to do that in Mecway. If it were static with hydrostatic pressure, you could use a low Young's modulus (hence low shear modulus) and a Poisson's ratio near 0.5 such as 0.4999 but that doesn't sound like it would work correctly for dynamics.
  • marc_ramseymarc_ramsey
    Bummer. Ok - thanks for your quick response!
  • rwhirleyrwhirley
    Mark - what you want to do is set the shear modulus an order of magnitude below the bulk modulus K, not below the Young's modulus E. Here's a link to a table that can then give you the E and nu to input to achieve a target K and G for your fluid. It should work fine as long as your fluid particle displacements aren't too large for the linearity assumptions in Mecway.
    https://www.researchgate.net/post/How_can_i_calculate_bulk_and_shear_modulus_for_any_kind_of_soil

    Watch your boundary conditions carefully, and be sure your mesh density will resolve the spatial wave behavior you are trying to resolve.
  • marc_ramseymarc_ramsey
    Oh - this is fantastic! Thank you!
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