Fluids

Fluids

Phase change with turbulent flow

    • pcsingh
      Subscriber

      Hi all,

      Good evening

      I am trying to simulate a turbulent flow over a PCM plate. I have used the k-epsilon model with enhanced wall function. A coupled algorithm is used. I have treated phase change material as a solid domain. When I compared my results with published data, what I got is the melting fraction is coming very low as compared to the reference paper(let's say at time(t)=3500 sec, the reference paper has a liquid fraction of 0.24 while I am getting only 0.17. I have used constant values for all properties of PCM (same as the reference paper). Can anyone point out where I am doing wrong? I have used the same boundary conditions as the reference paper. Which parameter is responsible for such a low value melting fraction?

      It is my humble request to share some suggestions.

      Regards

      Prakash S

    • Rob
      Ansys Employee

      When you say you're treating the PCM as a "solid" domain, do you mean you patched fluid below the solidus temperature or that it's a solid zone in Fluent? 

    • pcsingh
      Subscriber

      Good afternoon Rob sir,

      Yes, it means I am patching it below the solidus temperature.

    • Rob
      Ansys Employee

      The PCM is a part of the fluid domain so the liquid-solid boundary is inside the fluid, ie wall functions have no effect at that position. How is the paper returning volume fraction from their model (or experiment)? Some images of what's going on might help. 

    • pcsingh
      Subscriber

    • Rob
      Ansys Employee

      That proves you have a different result to the paper. It's not overly useful for working out why. How does the flow field compare, how are you measuring "melting fraction" etc. 

    • pcsingh
      Subscriber

      Report definitions ---area-weighted average----melting----liquid fraction.

      With due respect sir, where I am doing wrong? What could be the possible reasons for such a deviation? how can I find where I am doing wrong? 

       

    • Rob
      Ansys Employee

      I don't know. Without some clues I can't help. There's a reason I asked about the flow field..... 

    • pcsingh
      Subscriber

      With due respect I am new to this field so can you explain how to compare flow field so that I can share it with you?

    • Rob
      Ansys Employee

      You look at what's going on in the model using contours, vectors, pathlines etc. Then see how that relates to the model(s) in the paper. I suspect you need to go through some of the tutorials: they're found in the help system. 

    • pcsingh
      Subscriber

      Sir, the melting contours are matching more or less with the reference paper. I will go through the pathlines. Let me find those tutorials. By the way, thank you a lot rob sir for the guidance. I am also new to the Ansys forum, so can you guide me where to find those tutorials? 

    • Rob
      Ansys Employee

      Click on "Help" in Fluent and find the Ansys button in top left of the window: it's all web based. 

    • pcsingh
      Subscriber

      ok sir

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