SPH Parameters

Ovunc2
Ovunc2 Altair Community Member
edited November 2020 in Community Q&A

Hello,

I'm working on flow in a rectangular pipe. (Figure 1)

I have an idea about the use of the Mp and h parameters when creating SPH particles in a closed tank.

  1. Since SPH particles are not created in a fixed volume, how are the h and Mp parameters determined? ( in SPH_Prop)
  2. Do you have a document containing information about the following parameters? (Figure2)
      • Quadratic bulk viscosity (Prop_SPH parameters)
      • Linear bulk viscosity (Prop_SPH parameters)
      • Conservative smoothing coefficient (Prop_SPH parameters)

 

  1. How can I reduce its distance indicated by x in Figure 3?
  2. Is the fluid viscosity linear or can it also be entered nonlinear?

 

Thank you.

Regards,

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Answers

  • Andy_20955
    Andy_20955 New Altair Community Member
    edited November 2020

    Hi,

    1) I think you can still create the SPH parameters in HyperMesh.  HyperMesh creates particles should be spaced evenly in all directions.  It isn't recommended to space the particles in closer in one direction than another

    2) The default values for qa and qb are set to provide some damping for high speed shock wave type problems.  This damping provides stability.  For your case you could reduce the values of qa and qb.  For no damping use

    qa = 2.0e-30
    qb = 1.0e-30

    For alpha (conservative smoothing length) I would use the default value. 

    3) You should not reduce the X distance without reducing the distance in all directions.

    4) The viscosity mentioned on /PROP/SPH are numerical and meant to provide damping and stability to the solution.  For the fluid properties see /MAT/HYD_VISC/ + a /EOS. 

    Thanks,

    Andy

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