text: * From Small Disturbances
  : (subsonic)
  * From Divergence Theorem
  * Let Velocity U be a twice continuously differentiable function in a region of volume V in space.  This function is the stream function .
  * Let P be a point in the volume V
  * Let S be the surface boundary of the volume V.
  * Let Q be a point on the surface S, and .
  As Q goes from inside V to the surface of V, 
  * Therefore:
  For :, where the surface normal points inwards.
  This equation can be broken down into both a source term and a doublet term.
  The Source Strength at an arbitrary point Q is:
  The Doublet Strength at an arbitrary point Q is:
  The simplified potential flow equation is:
  With this equation, along with applicable boundary conditions, the potential flow problem may be solved.