Fluids

Fluids

Use of convergence condition vs residuals – CFD

    • pv00170
      Subscriber

      I am checking the drag coefficient, and I thought maybe to use a convergence condition of the drag by defining a stop criterion of 1e-05 and use iterations 5.

      If I apply this, convergence condition of the drag coefficient is met with continuity residual around 1e-03. As far as I have heard, a residual of 1e-05 would be a “nice” one. But the convergence condition is met before, is it okay to automatically stop the iterations of this time step when the convergence condition is met (in this case continuity residual is 1e-03) or should I wait for residuals to reach continuity residual 1e-05 even though drag coefficient per iteration does not vary?

      I mean, am I loosing too much “reality” by stopping the time step when drag coefficients criteria are met?

      I attached a plot to ease what I am trying to explain!

    • Rob
      Ansys Employee

      That's something you need to decide. You do need to check more than just lift/drag in your model though. I assume there's a wake region in your model? 

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