[en] A technique is described for numerical calculation of two-dinonsional ditributions of mutually-consistent flow characteristics and temperatures in coolant and structural elements of heat exchangers, flow parts of reactors etc. (associated problem), without reference to configuration of the flow part and element relative position. The calculation is performed with account of inertial forces, friction against distributed hydraulic obstacles and adjacent fluid layers, thermal convection forces, with regard to the effect of distributed in flow part consumption sources and sinks and different types of boundary conditions. The temperature distribution calculation is distinguished by similar universal character