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.
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:
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