How to create isosurface and rakes to find film thickness over the cylinder

    • Prudviraj

      Dear sir, I am beginner to the fluent, can someone suggest how to create isosurface and rakes to calculate water film thickness over the cylinder with respect to circumferential angle....I am attaching an image for your reference only....

    • Karthik R


      You could try to create an iso surface of your volume fraction (say 0.5). Since your simulation is 2D, it will give you a curve. If you plot the y-coordinate of this curve, you should get the film thickness (in some form - might require additional manipulations depending on your position of the origin).

      Please test this and let us know.

      Thank you.



    • Prudviraj

      Dear sir, I have attached images after creating the isosurface volume fraction of water 0.5...please suggest me the next steps to find film thickness with respect to circumferential angles.......

    • Prudviraj

      Dear sir, yesterday I read this attached image and how they measured in CFD POST......Can you please elaborate on how to find film thickness over the cylinder at various angles using CFDPOST with the similar approach I have attached...

      Your support will be appreciated......




      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.

    • DrAmine
      Ansys Employee
      You create rakes or lines over each line you use a user variable with 4*alpha phase 2 * alpha phase 1.
    • Prudviraj

      Dear sir, please suggest how to create radial rakes for every 30-degree angle over the cylinder...

    • DrAmine
      Ansys Employee

      You do them manually by providing the starting and end point which corresponds to 30° intervals or via script. Either in Fluent or in CFD-Post.

      If you have EnSight you can ise "By constant on part sweep" method which you can then easily create a sweep in the Theta direction.

    • Prudviraj

      Sir, i have created lines by providing starting and endpoint in CFDPOST.....will you please suggest how to measure only water film thickness at these lines. or using these lines....Here attached images are for your understanding.....Your guidance will be highly appreciated in this regard....

    • fit78

      Alternatively, you can generate a polyline from the water fraction contour. Choose the contour level you see fitting the fluid film.

      Once you generated the polyline, generate an XY plot. You will get something like this

      Then you can export the XY plot and open it in a spreadsheet.

      By using X^2+Y^2=R^2, you can find the R which is the distance of the fluid film from the center axis.

      Easily, you may find the thickness by substracting the radius of the cylinder you were working on from the R value. 

      To find the location of the film thickness, just use trigonometry since you already have the X and Y location.

      Hope this helps.


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