Model for shear-dependant concentration profile has been proposed. The model implies position-dependence of transverse flow and shear-dependence of diffusivity. Flow is assumed to be isothermal, incompressible, fully developed and steady-state. The model permits analysis of the influence of longitudinal or transverse velocity, particle size to be separated and channel geometry on configuration of concentration profile. Proposed model allows analysing the influence of shear rate at the membrane surface on the CP degree. The model can be used for prognoses of the effect of shear rate on the intensity of gel polarisation and membrane fouling. The solution does not contain digital integration and can be built into algorithm for modelling longitudinal distribution of CP degree.