text: to. the turbulent 
  boundary layer 
  takes place, the boundary 
  layer thickens and grows at a more rapid rate. 
  the 
  (The small scale, turbulent 
  boundary layer should not be confused with 
  the 
  large scale turbulence associated with 
  airflow separation.) The flow in the turbu- 
  lent boundary layer allows the air particles to 
  travel from one layer to another producing an 
  energy exchange. However, some small lami- 
  nar flow continues to exist in the very lower 
  levels of the turbulent boundary layer and is 
  referred to as the “laminar sub-layer.” 
  The 
  turbulence which exists in the turbulent bound- 
  ary layer allows determination of the point of 
  transition by several means. Since the turbu- 
  lent boundary layer transfers heat more easily 
  than the laminar layer, frost, water, and oil 
  films will be removed more rapidly from the 
  area aft of the transition point. Also, a-small 
  probe may be attached to a stethoscope and 
  positioned at various points along a surface. 
  When the probe is in the laminar area, a low 
  “hiss” will be heard; when the probe is in 
  
  As soon as the transition 
  
  52 