Effect of the Presence of Semi-circular Cylinders on Heat Transfer From Heat Sources Placed in Two Dimensional Channel

Abstract

The effect of a semi-circular cylinders in a two dimensional channel on heat transfer byforced convection from two heat sources with a constant temperature has been studiednumerically. Each channel contains two heat sources; one on the upper surface of thechannel and the other on the lower surface of the channel. There is semi-circular cylinderunder the source in upper surface and there is semi-circular cylinder above the source inlower surface. The location of the second heat source with its semi-cylinder has beenchanged and keeps the first source with its semi- cylinder at the same location. The flowand temperature field are studied numerically with different values of Reynolds numbersand for different spacing between the centers of the semi-cylinders. The laminar flow fieldis analyzed numerically by solving the steady forms of the two-dimensional incompressibleNavier- Stokes and energy equations. The Cartesian velocity components and pressure on acollocated (non-staggered) grid are used as dependent variables in the momentumequations, which discretized by finite volume method, body fitted coordinates are used torepresent the complex channel geometry accurately, and grid generation technique based onelliptic partial differential equations is employed. SIMPLE algorithm is used to adjust thevelocity field to satisfy the conservation of mass. The range of Reynolds number is (Re=100 – 800) and the range of the spacing between the semi-cylinders is(1-4) and the Prandtlnumber is 0.7.The results showed that increasing the spacing between the semi-cylinders increases theaverage of Nusselt number of the first heat source for all Reynolds numbers. As well as theresults show that the best case among the cases studied to enhance the heat transfer is whenthe second heat source and its semi-cylinder located on at the distance (S=1.5) from thefirst half of the cylinder and the Reynolds number is greater than (Re ≥ 400) because of theseparation behind of the first semi-cylinder where it works to reduce the area of sectionflow, and this is leading to increase the speed and thus increases the rate of heat transfer. Acomparison of numerical results agrees well with published results.