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PROPELLER CAVITATION

saji vf

Hello,

we are trying to capture propeller cavitation for 10 deg with time step size=0.0028 for periodic mesh with K-omega (sst menter). we were able to observe the cavitation pattern after some 6000 time steps,

But in the residuals the K started to increase after 5000 time steps and OMEGA is fluctuating from the start(>1000).  what could be the possible reason ?

The same periodic mesh was used in FLUENT Software too, got the required cavitation.

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  • 0

    Hi,

    There could be a thousand reasons why residuals could increase and fluctuate:

    - verify settings of cavitation

    - verify mesh quality

    - make sure convergence rate is acceptable per time step (verify pressure solver, non linear iterations, etc.)

    A picture would help to understand what you mean by increase and fluctuate. That is said, having fluctuating residuals does not shock me when doing cavitation.

    Is Fluent using the same cavitation model than Fine Marine?

    I am not sure we ever tested ourselves periodic meshes with cavitation. Is the mesh really periodic matching and considered like this by Fine Marine ? Do you see the periodics with the periodic condition? Because we could also treat them as FNMB, meaning "non matching boundaries"...

    Best regards,

  • 0 in reply to Benoit Mallol

    In Fluent the sauer model is used similar to fine marine.

    The periodic mesh in fine marine is validated for open water in our case. is Fine marine compatible for cavitation with periodic mesh ?

    OMEGA in monitor relates to Turbulent frequency or Turbulent dissipation rate ?

    The best practices of cavitation are set from tutorial and time step size taken is 0.028 for 10 degree and mesh quality is good enough with target y plus less than 1

Reply
  • 0 in reply to Benoit Mallol

    In Fluent the sauer model is used similar to fine marine.

    The periodic mesh in fine marine is validated for open water in our case. is Fine marine compatible for cavitation with periodic mesh ?

    OMEGA in monitor relates to Turbulent frequency or Turbulent dissipation rate ?

    The best practices of cavitation are set from tutorial and time step size taken is 0.028 for 10 degree and mesh quality is good enough with target y plus less than 1

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