Moving shock

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Moving 'Shock' is a situation where the shock is moving and does not stay in one location. It is sometimes referred to as shock dynamics.

In many situations, the shock is moving at a variable speed. However, this variable speed can be considered as a constant velocity to which many analytical tools can be applied. In this case, the moving shock can be transformed to a "stationary normal shock" by attaching the coordinates to the shock.

There are two broad categories of this shock, "open valve" and "close valve". The open valve referres to situations when high-speed gas runs into slower-moving gas. In an extreme case this open valve case is of high-speed gas running into a still medium. The "close valve" referrs to the case where shock is generated as a result of the shock reflecting from a solid (relatively hard material) and the shock is propagating upstream. Normally, when the two sides of the shock are moving, the word "partially" is also applied.

The governing equations of the shock wave were well established well before World War Two. Yet, in many cases no analytical solution was given. Recently, Bar-Meir has derived solutions to many of the cases. For example, the shock speed as results of piston movement became a simple analytical solution. These solutions show, for example, that when one opens the valve in his garden and the pipe is empty, the flow initially contains a moving shock that creates extremely large temperature increase for a few milliseconds. The phenomenon of the moving shock has many industrial applications.