Fluids

Fluids

How do I plot variation of drag coefficient along the curve of a wall (cylinder for example)?

    • n0t_sm0L
      Subscriber

      Fluent post processing allows you to plot pressure coefficient along a wall, but how do I do the same for drag coefficient? I know how to set up a drag coefficient report file and report plot.

      Also, why does Fluent not allow me to "plot along curve length" when I'm in parallel? It only allows me to do so in serial.

    • Rob
      Ansys Employee
      For the latter https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v211/en/flu_ug/flu_ug_sec_plot_solxy.html Hint to access the link read the Rules and Guidelines section of the forum.
      Never tried plotting it, but I think it's because drag coefficient is a force whereas pressure coefficient is a scalar value.

    • n0t_sm0L
      Subscriber
      Thanks for the link.
      Fair. But even though it is a force, I think I should still be able to plot a component of the force along one direction, about the surface of the cylinder right? Because, the same is possible with velocity. Like, for a boundary layer problem, velocity can be plotted along a line/plane to get the velocity profile along one direction. It seems possible in my head, I'm just not able to figure out how to do it in software. Unless I'm making a fundamental mistake conceptually.
    • Rob
      Ansys Employee
      Forces only exist on walls, and are reported in a separate section to the field variables: so I don't think there's a plot option to find.
      Re the why, I think there is a fundamental concept and it's been a long time since I thought about those.
    • aitor.amatriain
      Subscriber
      I guess you have to do it manually (UDFs). You need yo compute the drag force (sum of pressure drag and viscous drag) and divide it by the reference dynamic pressure.
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