How do you explain the formation of shockwave on the wing surface during near sonic flight?

Question

Explanations of shockwave for the common folks (youtube videos, googling) all tend to focus on successive sound waves generated by the air craft traveling outward in circles (sphere).

That to me, only explains why the boundary of a sockwave is a straight line (cone). It doesn't really explain:
[1] why the sudden pressure or velocity change of the air after the boundary.
[2] I can't use that to explain the shockwave on wing surface.

I have a feeling that shockwave on wing is not so much related to noises made by the plane, but it is related to solid cutting into liquid forcing the liquid into some behaviors, that in turn acts back onto the surface.

What I think I understand: sound wave being a planar wave of pressure, bernoulli effect and lift.

so on those foundations, could some one explain how is sockwave formed, and why is it parpendicular to the wing surface.

if possible:
I prefer microscopic understandings, as in layers of particles, starting from the layer touching the surface of the wing and explain our way layer by layer away from the surface.

Answer 1

Here is a slightly different way to think about this, which I hope will help. First imagine a wing traveling through air at subsonic speed. Our point of view is attached to the wingtip and looking straight down the leading edge, so what we see is parcels of air flowing towards the leading edge and splitting into two streams- one goes up and over the top surface and the other goes down and under the bottom surface.

those parcels of fluid air must pick up a velocity perpendicular to their original direction of travel so they can get out of the way of the leading edge of the wing. Now the fastest speed any parcel of fluid can assume here by itself is the speed of sound, but since the wing is subsonic the parcels of incoming air can easily flow up or down as required to get out of the way of the advancing wing. the velocity vector of any parcel then is the vector sum of its incoming velocity relative to the wing and this sideways component. New parcels of incoming air can feel the sideways velocity component of the parcels already in contact with the leading edge and so the splitting process actually begins slightly ahead of the leading edge.

All this changes when the wing approaches supersonic. There's less time available for setting the incoming air into sideways motion ahead of the leading edge and so the incoming air begins getting squeezed between the wing's leading edge and the parcels of incoming air behind it. The splitting point moves closer to the leading edge as this compression effect takes hold.

When the leading edge goes supersonic, the presence of the advancing wing can no longer be communicated in advance of its arrival and the air just ahead of the leading edge has no way to get started moving sideways before it smacks into it, and all the while, new parcels of incoming air are similarly piling up just ahead of the leading edge and getting compressed too.

A thin wall of compressed air then builds up sideways at the tip of the leading edge and gets forced to move forward by the leading edge into the incoming air, which cannot get out of its way.

That thin wall is the shock wave.