Transonic buffet - reason for a rapid movements of the shockwave along the wing chord line?
Viewing the airfoil as a rotating cylinder, the highest velocity on it's surface occurs at the top of the cylinder (90° using polar coordinates) therefore that's where the shockwave begins and hence where flow separation will start

I know that as the free stream velocity gets higher the point at which the velocity on the surface on the airfoil (cylinder) goes supersonic occurs closer and closer to the leading edge therefore the first tendency of the shockwave is to move "forwards" (towards 0° on the cylinder representation)

I also know that flow separation occurs under an adverse pressure gradient however between 90° and 0° the pressure gradient on a cylinder is favourable (due to geometry), therefore perhaps that is why the flow reattaches when the shockwaves moves &lt;90°