Fluids

Fluids

Can I write a UDF that is a velocity profile or force profile at a give region/line?

    • Antang
      Subscriber

      If I have experimental data on how a unique micro-fan like object behaves and know that it has a given velocity profile, can I somehow write a UDF that defines that profile?  I've written basic UDFs that specifies a momentum source (that is a force) but I guess in this case I want to define the effect, not the cause.  I have measured and mapped the velocity profile of this micro-fan object which is basically the effect of a momentum source.  I know the cause of the velocity profile is the unique force profile but I don't have the instrumentation to measure that force. 


      I plan to possibly go in reverse and figure out a force profile or just skip that and go straight into the applications of this micro-fan like object by putting it over a wing or between some wings or something.  If anyone knows if this is possible please let me know!

      Thank you!

    • DrAmine
      Ansys Employee
      If you want to prescribe the motion of center of gravity you can use c.g. motion define macro or just a profile.
    • Antang
      Subscriber

      Its not the center of gravity nor is it really a boundary condition.  I could create a boundary condition velocity inlet with a profile but velocity inlets input mass into the system.  I want to define a velocity profile at just a particular section or define a force profile at a particular section.

    • DrAmine
      Ansys Employee

      Is is velocity inlet boundary? 

    • Rob
      Ansys Employee

      I think you're after a FIX condition. You'll need a cell zone for that. 

    • DrAmine
      Ansys Employee
      After reading the first post i agree with my colleague. Either you use that fixed values option and here you require a dedicated cell zone or use UDF to create a fixing value.
    • Antang
      Subscriber

      Now I've never had much experience creating fluid cell zones.  If i wanted to test this idea and just created a rectangular domain to be where i specific a velocity profile inside a larger box which is my fluid domain, In design modeler do I need to create two different bodies or just two different faces that can be made by just projecting that velocity profile box into the fluid domain?

    • Antang
      Subscriber

    • DrAmine
      Ansys Employee

      You create a multibody part in DM to get a conform mesh. In meshing you provide dedicated names for each region.

    • Antang
      Subscriber

      In 2D I create two cell zones with the boolean function but in Fluent and Mesher it reads the two zones as both walls instead of an outer wall and inner interface.  How can I specify that the inner wall is actually a interface between the box fluid and inside cell zone

    • DrAmine
      Ansys Employee
      Change it to interior.
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