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Purpose -The purpose of this paper is to examine the turbulent fluid flow and heat transfer characteristics for rectangular channel provided with solid plate baffles which are arranged on the bottom and top channel walls in a periodically staggered way. Design/methodology/approach -The turbulent governing equations are solved by a finite volume method with the second-order up winding scheme and the k-v turbulence model to describe the turbulent structure. The velocity and pressure terms of momentum equations are solved by SIMPLE (semi-implicit method for pressure-linked equation) algorithm. The parameters studied include the entrance Reynolds number Re (5.10 3 -2.10 4 ), the baffles height are fixed at (h ¼ 0.08 m); whereas three different baffle spacing were considered S 1 ¼ D, S 2 ¼ D/2 and S 3 ¼ 3D/2 and the working medium is air. Findings -In this work, it is found that vortex shedding generated by the baffle on the upper wall can additionally enhance heat transfer along the baffle surfaces. The wavy flow significantly changes the recirculating zone behind the last baffle. Finally, changing the baffles spacing seemed to reduce to changing the heat transfer surface between the solid and the fluid in the sense that higher heat transfer is obtained for lower spacing between baffles. Originality/value -The results of the numerical calculations of the flow field indicate that the flow patterns around the solid baffles depending on the spacing of the baffles and it significantly influences the local heat transfer coefficient distributions. The problem is inversely proportional for the friction factor. Turbulent flow and heat transfer¼ production of turbulent kinetic energy due to velocity gradient through (m 2 /s 2 ) G v ¼ kinetic energy production due to buoyancy (m 2 /s 2 )Greek symbols v ¼ the specific dissipation rate of turbulence energy (m 2 /s) r ¼ density of the air (kg/m) l ¼ thermal conductivity (w/m8C) m l , m t ¼ laminar, turbulent viscosity (kg/m s) m f ¼ dynamic viscosity of fluid (kg/m s) m e ¼ Effective viscosity (Pa· s)¼ the shear-stress to the wall (kg/(s 2 · m)) Dp ¼ pressure losses G k , G v ¼ effective diffusivity of k and v, respectively a ¼ coefficient of thermal expansion (k 2 1 ) d ij ¼ stress tensor a * ¼ coefficient damps the turbulent viscosity causing a low-Reynolds-number correction a * 1

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This article presents a computational analysis of the turbulent flow of air in a pipe of rectangular section provided with two waved fins sequentially arranged in the top and the bottom of the channel wall. The governing equations, based on the k-ε model with Low Reynolds Number (LRN) used to describe the turbulence phenomena, are solved by the finite volume method. The velocity and pressure terms of momentum equations are solved by the SIMPLEC algorithm. The profiles of axial velocity, the velocity fields and the drag coefficient were obtained and presented for all the geometry considered and for selected sections, namely, upstream, downstream and between the two waved baffles. This contribution lead to results which were analyzed by the use of the solid, plane baffles, waved and inclined with active degrees of 0° up to 45° with a step equal to 15 degree and directed towards the left. Over the range of the study, the undulation of the baffles induced with an improvement on the skin friction of about 9.91 % in the case of α=15°, more than 16% in the other cases, and concerning the pressure loss, the undulation of the baffles was insured improvements starter from 10,43% in all cases compared with the baffles of plane form