Fluids

Fluids

Questions about boundary condation for particles

    • 1155168052
      Subscriber

      I would like to ask about the meaning of the return PATH_ABORT of the particles return status in the udf boundary conditions. According to the Ansys Fluent udf manual 2.5.1.DEFINE_DPM_BC, for the return status PATH_ABORT, the particle will be stopped and considered to be aborted. But when I define the status of the particles that reach the boundary as return path abort, I find that the particles still have velocity and can move with the airflow. May I ask the detail explanation about the udf return Path_ABORT?

      I test the udf of return path abort in a 1*1*1 m box, release 40000 particles with a file from 0-0.1 s. The figures are my procedure.

      My purpose is that when the particles reach the boundary, they stop moving and are not affected by the airflow, but still exist in the domain. I also try to use trap for the boundary condation, but "trap" cannot show the particle deposition distribution in a figure. Dose anyone have any suggestions for achieving this?

    • DrAmine
      Ansys Employee

      PATH_ABORT has the same effect as PATH_END and the particle is not tracked further. 

      I think you can use Trap BC, do sampling a long the wall to create a sample file which you might use to read the particles back for post-processing purposes. Though The TRAP BC does show the particle deposition distbriubtuon as Eulerian variable whenver you enable Acretion/Erosion rate calculation. 

    • 1155168052
      Subscriber

      DrAmine, thanks for your reply!

      I still confused about the "PATH ABORT". If the aborted particles are not tracked further, why the aborted particles can be seen in the "Results/Graphics/Particle tracks" and the console. Is that meaning aborted particles still in the domain but the fluent software donot computer this particle? Why the particle defined as "path abort" still have velocity?  What is the difference with path abort and path end?

      Thank you again for your kindly reply.

    • DrAmine
      Ansys Employee

      They are not tracked further but they are not deleted. They will have the velocity assigned to them at the moment they are aborted.

      • 1155168052
        Subscriber

        Thanks for your reply!

        I would like to ask the meaning of "not track". For path abort, is that mean the trajectory of particles not be calculated according to Newton's second law?

        But I found the particle can move on the boundary after reach the boundary and defined as abort. And the particle can still be tracked, seen from the console: "Advancing DPM injections ....number tracked = 1, escaped = 0, aborted = 1, trapped = 0, evaporated = 0, incomplete = 0, incomplete_parallel = 0".

         

         

    • DrAmine
      Ansys Employee

      Trajectory calculation will be stopped when using Abort.

      I recommend to trap the particles and rely on the contours of Acretion rates to see where they deposit. 

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