الفهرس 
Abstract
Computational MethodsOnly 14 pages are availabe for public view
 |  | from | 120 |  |  |
| | | from | 120 | | |
Abstract
This thesis investigates the effect of Reynolds number on the entrance length for wide range of flow conditions using Lattice Boltzmann method (LBM) and applying OpenMP parallel method.
LBM is an accurate promising method which focuses on the meso-scale for the solution of nonlinear partial differential equations and simulation of fluid.The LBM generally involves two steps: collision and streaming. One of most widely used collision model is the Bhatnagar-Gross-Krook (BGK) collision operator which applies the single time relaxation approximation. The collision step occurs locally in the sense that it does not require any spatial and temporal derivatives. Thus there is no numerical stability issue for this step. The streaming step following collision moves the updated distribution functions to neighboring nodes by perfect shift on a uniform mesh.from the Eulerian point of view, the streaming step is equivalent to solving pure linear wave equations. Compared to the macroscopic approach that solves the incompressible Navier-Stokes equations, there are two immediate advantages. One advantage is that the convection term becomes linear. The other advantage is that there is no need to solve the pressure-Poisson equation. These features make the LBM easy for parallelization.
First,we introduced a historical and theoretical background of lattice Boltzmann method. In this part some conclusions are drawn about the stability and other physical characteristics of the lattice Boltzmann method.
Then,we applied Lattice Boltzmann Method on a micro flow in two parallel plates. D2Q9 model in a wide range of Lattice dimensions has been used for the study. Reynolds numbers are considered in the range 0.476≤Re≤200 with viscosity υ= 0.05for the water working as a regular fluid. Results in chapter 3 indicated that the entrance length is changed significantly with varying the Reynolds number. Comparison between numerically predicted entrance length and measured values of entrance length shows a very good agreement. Moreover, the predicted velocity distributions at different locations along the entrance length are compared.