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Time step based on CFL number in VOF

    • aitor.amatriain
      Subscriber

      To whom it may concern,

      I an performing a multiphase simulation with VOF, and I would like to set the time step based on the Convective Courant Number (CCN) number. 

      The only option that the solver offers is the Global Courant Number (GCN), although this approach by default is too aggresive in my case. I have tried to set "Physics Based Constraint" on in the Settings option. However, in this case, the time step is still very aggresive, and the CCN and the GCN are not related. Based on the user manual, the "Physics Based Constraint" shoul be very conservative, in particular because it uses the CCN, but for some reason something is not okay.

      I would like to know if you could please inform be if it is possible to set (like in single-phase simulations) a time stepd that depends only on the CCN.

      Thank you in advance

    • SRP
      Ansys Employee

      Hi,

      you can enable adaptive time stepping, which allows the solver to automatically adjust the time step size during the simulation based on the solution behavior. This can help maintain stability while not being overly restrictive.

    • aitor.amatriain
      Subscriber

      Hello,

       

      Thank you for your answer. Adaptive time stepping based on what?

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