[jaegak]

Why does laminar separation occurs at 80~90 degrees from stagnation point in circular cylinder? But not over 90?

[kykim]

we can not predict exactly where the separation occurs. however we know that separation occurs at the adverse pressure gradient region. In inviscid vade, adverse pressure gradient starts from 90 degrees. In viscois flow, however, adverse pressure gradient starts before the 90 degrees owing to wall stress. The separation angle will be delay if free stream velocity increases but it is almost 90 degrees when larminar separation occurs. transition begins after that.