The necessity of correcting differential semiempirical turbulence models to calculate circulating flows of an incompressible viscous fluid is discussed. Approaches to taking account of the influence of the curvature of streamlines on turbulence characteristics are reviewed. Experience gained in modeling numerically two dimensional separated flows in a square and a cylindrical cavity on the wall of a plane-parallel channel is analyzed; an additional semiempirical constant in the expression for vortex viscosity of a modified shear-stress-transfer model is substantiated.