The analysis of the turbulent flow through pipe is important for many engineering Applications like fluid transport piping system, air conditioning devices etc. In this study, fully developed, turbulent channel flows with smooth walls were studied, providing some useful and extended information about these kinds of flows. The Reynolds-averaged Navier-Stokes (RANS) equations were solved along with turbulence models, namely k-¿ Reynolds stress models (RSM), and filtered Navier-Stokes equations along with Large Eddy Simulation (LES) to study the fully-developed turbulent flows in circular pipes with the help of ANSYS FLUENT 14.5 software .This model has been used to predict the different aspects of the fluid flow in a pipe, including the behavior of wall Y plus function at various Reynolds numbers, average shear stress and friction factor.