Fluids

Fluids

C_DT vs. CURRENT_TIMESTEP UDF

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    • Theodore St George
      Subscriber

      Hello,

      I'm trying to get a pseudo-timestep from each cell for a steady-state calculation. I was previously referred to C_DT(cell,thread) which appears to work well with the Density-based solver. However, upon switching to the Pressure-Based solver, even with Coupled and Pseudo Time Method turned to Global Time Step, utilizing C_DT(cell,thread)  causes Fluent to hard crash and close. The CURRENT_TIMESTEP command has no such issues, but I don't have any confirmation the timestep is indeed the actual pseudo timestep, not just a value that's held over from the last time I did a transient simulation. 

      Notably, I can extract a contour plot of the Time Step (Residuals -> Time Step) while using the Density-Based Solver, and I cannot while using the Pressure-Based Solver

      Is this the expected behavior and/or are there other commands I should be looking at?

    • Rob
      Ansys Employee

      CURRENT_TIMESTEP is for transient models. I suspect the C_DT is for the density based solver only, and there may not be an equivalent for pressure based. We're a bit limited in what we can offer for UDF support - other than the documentation. Other community members are not under the same restrictions. 

    • Theodore St George
      Subscriber

      Understood, thanks Rob.

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