Due to shear thinning of polymer melts with pseudoplastic flow behaviour a strong flection of the velocity profile close to the wall occurs. This effect is covered by the Weißenberg-Rabinowitch correction. Consequently the shear rates near the wall are higher than these from Newtonian fluids, where the calculation of the apparent shear rates is valid for (see part “Apparent values”). This effect is considered by the Rabinowitsch Weissenberg correction and adjusted. The corrected viscosity is calculated via the corrected shear rate and the shear stress close to the wall.