Wave equation - Poor man's solution

• Physicist's idea:
  • surround the interior region with damping material
  • add a friction term to the wave equation
    • 
  • damping τ(x) = 0 inside, gradually increasing in the boundary
  • careful choice of τ(x) to minimize reflections
• Result:
  • perfect for our purpose (teaching!)
  • but reflections remain, depending on wave length and incident angle