text: Jets emerging from a slot-jets creates stagnation point in between according to potential theory. The flow near the stagnation point can by studied using self-similar solution. This setup is widely used in combustion experiments. The initial study of impinging stagnation flows are due to C.Y. Wang. 
  Let two fluids with constant properties denoted with suffix  flowing from opposite direction impinge, and assume the two fluids are immiscible and the interface (located at ) is planar. The velocity is given by
  where  are strain rates of the fluids. At the interface, velocities, tangential stress and pressure must be continuous.
  Introducing the self-similar transformation,
  results equations,
  The no-penetration condition at the interface and free stream condition far away from the stagnation plane become
  But the equations require two more boundary conditions. At , the tangential velocities , the tangential stress  and the pressure  are continuous. Therefore,
  where  (from outer inviscid problem) is used. Both  are not known apriori', but derived from matching conditions. The third equation is determine variation of outer pressure  due to the effect of viscosity. So there are only two parameters, which governs the flow, which are
  then the boundary conditions become