Fluids

Fluids

Updating Node Position in Fluent

    • CarolineSCi
      Subscriber

      Dear friends,


      I would like to update the position of some nodes of my model in Fluent, but I am not sure how to perform it. This update should be done at least once after the solution of my model converges, then I will rerun the simulation with the updated mesh. To do so, I have a txt. file I exported from ANSYS APDL, where the ID and the position of each node is written. The position of the nodes is not described by any equation. I have read ANSYS manual, searched in internet and the solution I have found is to work with UDFs (DEFINE_GRID_MOTION) or UDMs. Moreover, I have written an UDF for the macro DEFINE_GRID_MOTION(name, d, dt, time, dtime), but it is not working, so I am wondering, whether this macro is really necessary. Besides, I have to describe on it the current time and the time step, however, my simulation is not transient.


      If any of you has an idea on how I could solve my problem it will really appreciated.


      Thanks a lot!

    • Rob
      Ansys Employee

      It's probably the correct macro, but how are you telling which nodes where to move? 

    • CarolineSCi
      Subscriber

      Dear rwoolhou,


      Thank you for your answer. At the moment I have a relative easy model, please see attached, so I can figure out which node will move. For a complex geometry it will be a problem and I will have to figure it out later on. Basically, fluid is passing though the green area, it generates body forces of it and therefore I use ANSYS APDL to simulate the reaction of the green area.Then I export the new node position in a txt. file and try to use UDF to update the new node position. Would you give me any extra advice?


       



       


       

    • CarolineSCi
      Subscriber

      Maybe it is important to say that I am not using the system coupling of ANSYS as I also have to take into account the deformation of the nodes inside of the green area (when the mesh will be refined). Therefore, the solution I have found was to use both Fluent and APDL separately.

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