Fluids

Fluids

How to find water film thickness over the cylinder at various circumferential angles

    • Prudviraj
      Subscriber

      Dear sir, I am working on water flowing over the cylinder using 2D VOF multiphase flow transient model......I want to calculate water falling film thickness over the cylinder. please, someone, suggest a way to find water film thickness using CFD Post pro/plot/any other way.


       


      Your support will be highly appreciated.

    • Keyur Kanade
      Ansys Employee

      As ANSYS Staff, we can not download attachments. Please insert images using insert image functionality. 


      if it is cylinder, you may need udf. experts may comment on this. 


      also moving this to fluid dynamics category to get better response. 


      Regards,


      Keyur


       


      If this helps, please mark this post as 'Is Solution' to help others.


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    • Prudviraj
      Subscriber

      Thanks, KKanade, please find the attached image for your reference.

    • Keyur Kanade
      Ansys Employee

      as mentioned, you will need a udf for this. 


      please go through help where you can find some examples of udf. then you will have to write your own udf. 


      Regards,


      Keyur


       


       


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    • Prudviraj
      Subscriber

      One of my friends suggested by creating the radial rakes there is a chance to find film thickness...can you please elaborate about radial rakes and suggest an alternative to find film thickness.

    • Rob
      Ansys Employee

      Try creating an iso-surface to pick up the free surface and then plot "Cell Wall Distance", it's in the Mesh field of contours. 

    • Prudviraj
      Subscriber

      Dear rwoolhou sir, please elaborate, how to draw isosurface and to find cell wall distance??

    • Rob
      Ansys Employee

      Click on help and review the Fluent tutorials, that'll show you how to create surfaces and the the cell wall distance, look in the field options in contours. 

    • Prudviraj
      Subscriber

      Dear sir, please elaborate......i want to calculate film thickness with respect to circumferential angle...........

    • Prudviraj
      Subscriber

      The response from the staff is very poor and totally disappointed. I have posted 1 week back still I did not get any appropriate solution.

    • Rob
      Ansys Employee

      No, I told you how to find the answers 4 days ago. Maybe do the tutorials? 

    • Prudviraj
      Subscriber

      Dear sir, How can I find film thickness with reference to the circumferential angle.

    • DrAmine
      Ansys Employee
      Be patient and check what my colleague suggested. He suggested you create iso surface of volume fraction = 0.5 and fimrom that surface you get with the variable cell wall distance the thickness of the film.
      You can create some rakes and also plot along the rakes the radial distance to the free surface after creating some custom field functions and checking the cell zone condition axis and center if rotation.
    • Prudviraj
      Subscriber

      Dear sir thanks for your suggestions, yesterday in one research paper I read regarding film thickness to be determined in CFD post only...I am attaching related data and how they measured including with image...please suggest me I am not getting....



      The corresponding mass flow rate to its velocity inlet is then recorded when a proper film distribution is achieved in simulation result. The thickness of water sheet film on tube surface is then measured based on angles of 15°, 30°, 45°, 60°, 75°, 90°, 105°, 120°, 135°, 150°, and 165° as shown in figure 8. These angles have been set as a reference values in accordance with many previous references. The numerical results have been analyzed in CFD-Post where 4 mm length of measurement lines were positioned normal to tube surface. These measurement lines acted as a parameters that measures water film thickness at specified angles as shown in Fig.


      The thickness of water film are extracted and plotted in a graph of thickness versus orientation angles. Each measurement data is measured by taking into account the difference of water volume fraction length which only 1.


      Dear sir, please elaborate above procedure applicable to my problem using CFD POST.....


      Your support will be highly appreciable....

    • DrAmine
      Ansys Employee
      I will lock this topic you raised the same question one more time.
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