Flow and heat transfer in a rectangular converging (diverging) channel: new formulation

Abstract In this paper, a model problem of viscous flow and heat transfer in rectangular converging (diverging) channel has been investigated. The governing equations are presented Cartesian Coordinates consequently they simplified solved with perturbation numerical methods. Initially, symmetrical solutions the boundary value found for upper half channel. Later on, these extended to lower then whole compared exactly matched each other small parameters involved problem. It is also confirmed that converging/diverging independent sign m (the slope). Moreover, skin friction coefficient at wall calculated graphed against existing different figures. observed walls decreased (increased) increasing $${c}_{1}$$ c 1 (thermal controlling parameter) diverging (converging). Pr (Prandtle number). For $${c}_{1}=0$$ = 0 , temperature profiles may be determined from rate $$\theta^{\prime } (1) = \frac{m}{{(1 + m^{2} )\tan^{ - 1} m}}$$ ? ? ( ) m + 2 tan - . behaves linearly Re* (modified Reynolds number) it increased (changed negative positive). asymptotically converges constant i.e. zero.