Turbulent wall-bounded flows are commonly encountered in engineering practice and are of considerable interests in a variety of industrial applications. This presence of wall significantly affects turbulence characteristics. If we want to solve the near-wall region a very fine mesh is necessary. The number of points needed increases at least like Re. This requirement makes the application of Large Eddy Simulation (LES) for high Reynolds (order of 10~6 -10~8) practically impossible. One solution is to apply near-wall modification, or wall models with a coarse mesh near the wall. When the grid is not fine enough to resolve near-wall structure, the near-wall must be modeled by specifying a correlation between the velocity in first node and shear stress at the wall. The objective of this study is to implement wall-function for LES simulation of channel flow. The sub-grid scales are modeled using Smagorinsky and Wale model. The first node is placed at y~+ ～ 49 for Re_τ = 4000 and 54 ≤ y~+ ≤ 200 for Re_τ = 16000. So the first node was located in log-law region and standard wall function was applied. Other modification was introduced in the calculation of the length-scale in the Smagorinsky model using the model proposed by Mason-Callen [7]. Another model introduced was the Werner - Wengler model [6].
展开▼
