  The contribution of the "rapid" part of the pressure diffusion to the
turbulent kinetic energy balance is analyzed, and a new model to describe its
effect is suggested. A new transport equation for the turbulent kinetic energy
is derived. The new k-equation does not require any modification in the
standard epsilon-equation. A new k-epsilon model, which includes the new
k-equation and the standard epsilon-equation, is validated in four separated
flows: a planar diffuser, over a backstep, in a channel with wavy walls, and in
an axisymmetric combustion chamber. It is shown that a new model reproduces the
mean velocity, shear stress, and turbulent kinetic energy profiles and the skin
friction coefficient in very good agreement with experimental data.
