The worldwide demand for storage of data continues rapidly so the number and size of the data center are increasing constantly. Significant power consumption is dedicated in the U.S in 2006 nearly 1.5% percent of overall electricity consumption in the U.S. and as a matter of fact, up to half of this power is spending in cooling of facilities (computer room air condition (CRAC) or computer room air handler (CRAH) in a data center. As energy consumption is huge the energy efficiency is an important issue to consider in the data center. Computation fluid dynamics (CFD) can be very useful in order to provide detail information about the airflow behavior in the existing data center and simulating a data center before it is built.