In this paper, the flow around bluff bodies with different cross sections and determination of forces acts on them are investigated.This paper presents the results of a numerical study on the flow characteristics and heat transfer over two equal square cylinders in a tandem arrangement. Spacing between the cylinders is 5 widths of the cylinder and the Reynolds number ranges from 1 to 200, Pr=0.71. Both steady and unsteady incompressible laminar flow in the two-dimensional regime are studied. A study of the effects of spatial resolution and blockage on the results is provided. In this paper, the instantaneous and mean streamlines, vorticity and isotherm patterns for different Reynolds numbers are presented and discussed. Also the global quantities such as pressure and viscous drag coefficients, Strouhal number and Nusselt number are determined and discussed for various Reynolds numbers.