text: trays the relative magnitude of dynamic and 
  viscous forces in the flow. 
  
  In order to compare the characteristics of 
  the laminar and turbulent boundary layers, the 
  velocity profiles (the variation of boundary 
  layer velocity with height above the surface) 
  should be compared under conditions which 
  could produce either 
  turbulent 
  flow. The typical laminar and turbulent pro- 
  files are shown in figure 1.24. The velocity 
  profile of the turbulent boundary layer shows 
  a much sharper initial change of velocity but 
  a greater height (or boundary layer thickness) 
  required to reach the free stream velocity. 
  As a result of these differences, a comparison 
  will show: 
  
  While the actual magnitude of the Reynolds 
  Number has no physical significance, the 
  quantity 
  is used as an index to predict and 
  correlate various phenomena of viscous fluid, 
  flow. When the RN is low, viscous or fric- 
  tion forces predominate; when the RN is high, 
  dynamic or inertia forces predominate. The 
  the equation for 
  effect of the variables in 
  Reynolds Number should be understood. The 
  RN varies directly with velocity and distance 
  back from the leading edge and inversely with 
  kinematic viscosity. High RN’s are obtained 
  with large chord surfaces, high velocities, and 
  low altitude; low RN’sresult from small chord 
  surfaces, low velocities, and high altitudes- 
  high altitudes producing high values for kine- 
  matic viscosity. 
  
  (1) The turbulent boundary layer has a 
  fuller velocity profile and has higher local 
  velocities immediately adjacent to the sur- 
  face. The 
  turbulent boundary layer has 
  higher kinetic energy in the airflow next to 
  the surface. 