Fluids

Fluids

How can I pinpoint the exact location where the flow separates?

    • Keyur Kanade
      Ansys Employee
      How can I pinpoint the exact location where the flow separates?
    • Karthik R
      Administrator

      Hello @kkanade ?

      When a flow around a body encounter an adverse pressure gradient it can separate from the body surface and create a zone of recirculating fluid. If you are looking at the boundary layer velocity profile over a body. When it encounters an adverse pressure gradient (namely pressure increasing as we move downstream) the flow velocity reduces until it actually reverts its direction. Along the boundary layer profile there would be a point where dV/dn = 0 at the wall. This is the point of flow separation.


    • prajput
      Ansys Employee

      Hello @kkanade ,

      Just to add to @Kremella 's response. You can also look at the variation of wall shear stress, at the point of separation the values of wall shear stress is zero. If you'd like to know more, then do check out these free courses on fluid mechanics from the link:

      https://courses.ansys.com/index.php/courses/learn-fluid-dynamics-basics/

    • adbiahmed
      Subscriber
      Hi, nI understand it was a while since this Question was posted but I am having trouble with Fluent not showing the later separation of a turbulent boundary layer compared to a laminar boundary layer. nThis is for flow over a sphere, where experimental studies suggest TBL to separate later than laminar for sub-critical Reynold's.n Does anyone here know why Ansys might be doing that?.
    • Karthik R
      Administrator
      Hello,nWhat kind of mesh are you using in your problem? Can you post a few screenshots? Also, which turbulence model are you using, and what is your Reynolds number (based on the dia of the sphere)?nAlso, what does the flow look like in your current model?nKarthikn
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