Heat transfer in an inlet region of tubes with rectangular section on laminar viscous liquid flow at boundary conditions of the second kind

The problems are solved involved in determination of stable heat exchange on the initial portion of a rectangular tube at laminar flow of the viscous fluid. The effect is studied of the cross section side ratio and configuration of heated and non-heated walls of the channel at the second-type boundary conditions. It is supposed that the profile of the tube entry speed ensures the stabilized flow and that the flux is directed from the walls towards the centre of the tube. The problem is solved for the event when the physical properties of the fluid are considered to be constant and for the event when it is necessary to take into account dependence of the viscosity on the temperature. The equations for movement and energy are obtained from the Navje-Stokes and Fourier equations with the use of simplifications which consist mainly in ignorance of the speed components normal to the channel axis and longitudinal variation of the pulses. The calculations have been performed on the computer with the use of the final difference method, by making plots on a rectangular grid compressed in the large temperature gradient regions