In Mach Buffet, what happens to the boundary layer behind the shock wave?

• A. It remains attached to the wing.
• B. It becomes laminar and smooth.
• C. It may separate from the wing due to the shock wave.
• D. It strengthens the lift.

Answer: (C)

When a shock forms on a wing at transonic speeds, the flow behind it experiences a sudden rise in pressure. That abrupt pressure increase creates a strong adverse pressure gradient near the surface. If the boundary layer loses enough momentum to overcome this gradient, it can no longer stay attached and instead separates from the wing surface. This boundary-layer separation behind the shock is a hallmark of Mach buffet, driving unsteady flow and lift fluctuations.

So the boundary layer behind the shock may detach from the surface, which is why this option is the best choice. It’s not typically kept attached, nor does it simply become laminar and smooth, and separation tends to reduce lift rather than strengthen it.