Why is the inlet temperature(1
 

Why is the inlet temperature(1K) and pressure(1P) for the forward step case so small? I am thinking of adapting it to flow through a nozzle.
Shuo

I guess, this is just to make
 

I guess, this is just to make things simple. the properties of the fluid is so chosen that at temperature 1K the speed of sound becomes 1m/s so that u=3 -> M=3. since ideal gas equations are used, this does not make any difference.