When flow passes over the tube bundles, energy of flow transfers to the tubes. The Fluid Induced Vibrations (FIV) imposed on the tubes is one of the important problems in analyzing the tube bundles and causes several problems. In this work, first, laminar flow around circular cylinder asymmetrically in a channel is simulated. The Reynolds number is 20 and 100. The lift forces to tube are not zero. Also flow over tube bundle with twenty-four rods is simulated and flow characteristics are obtained. In this problem, the Reynolds Number is 50 to 40000 and the pressure contours, streamlines and velocity vectors are obtained. At last, turbulent flow over a tube bundle with special boundary condition is calculated. For turbulent modeling, the Large Eddy Simulation Method with Smagorinsky and Mix model and the Parallel programming method is used. Flow pattern and characteristics are obtained. Numerical results show a very good agreement with experimental results and reveal interesting flow behavior which is applicable to steam generators of nuclear power plants.