In many industrial applications, heat must be transferred in the form of either an energy input into the system or removal of energy produced in the system. In this study, heat transfer and flow characteristics of hexagonal finned heat sinks which optimized according to the Taguchi experimental L-18(2(1)*3(7)) design method in channel flow was analyzed numerically. Ansys-Fluent Icepak module was used in CFD analysis. The analysis carried out for two hexagonal finned optimized heat sinks in 3 different fin heights and 5 different flow velocities. Nusselt number increased with increasing Reynolds number for OH-1 and OH-2 heat sinks with all fin heights. Also, results showed that the friction factor decreased with increasing Reynolds number for all fin heights. According to CFD results, Nu-Re and f-Re variations were obtained and compared with experimental results. The experimental results and the numerical results were quite consistent. (c) 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V.