Calculations of unsteady laminar flows decelerated on the average with separation

Numerical simulations of unsteady laminar flow separation in a pulsed boundary layer in an unfavorable mean pressure gradient are presented. An implicit upstream decentered scheme is developed and applied to separated unsteady laminar flow in a diffuser. A second method based on the alternating direction technique associated with fifth-order Hermitian relations is then investigated as a means of limiting the numerical viscosity effects connected with the first scheme.