text: 5.00 
  
  The example of supersonic compressible flow 
  is complicated by the fact that the variations 
  of flow density are related to 
  the changes 
  in velocity and static pressure. The behavior 
  of supersonic compressible flow is that a con- 
  vergence causes compression while a divergence 
  causes expansion. Thus, as the supersonic 
  compressible flow approaches a constriction 
  and the streamlines converge, velocity dc- 
  creases and static pressure increases. Con- 
  is maintained by the 
  tinuity of mass flow 
  increase in flow density which accompanies the 
  decrease in velocity. As the supersonic com- 
  pressible flow enters a diverging section of the 
  increases, static pressure de- 
  tube, velocity 
  creases, and density decreases to accommodate 
  the condition of continuity. 
  Hypersonic-Mach numbers above 5.00 
  While the flight Mach numbers used to define 
  these regimes of flight are quite approximate, 
  it is important to appreciate the types of flow 
  In the subsonic regime 
  existing in each area. 
  it 
  that pure subsonic airflow 
  is most likely 
  the 
  exists on all parts of the aircraft. 
  transonic regime it is very probable that flow 
  on the aircraft components may be partly sub- 
  sonic and partly supersonic. The supersonic 
  and hypersonic’ flight 
  regimes will provide 
  definite supersonic flow velocities on all parts 
  of the aircraft. Of course, in supersonic flight 
  there will be some portions of the boundary 
  layer which are subsonic but the predominating 
  flow is still supersonic. 