Lattice-Boltzmann Simulation on Fluid Dynamics and Mixing in Micro Channels
|Course||Chemical Engineering and Technology|
|Keywords||Lattice Boltzmann Method Multiphase flow Microchannel T- micromixer Parallel computing|
Lattice Boltzmann method for calculating fluid dynamics but not limited to the field of a the emerging numerical simulation method, in the past 20 years, has made many important achievements. The method differs from the traditional computational fluid dynamics methods based on macroscopic equations discrete mesoscopic simulation method based on the Boltzmann equation with simple, easy-parallel features, widespread concern in recent years by a growing number of scholars . This article describes the basic principles of the lattice Boltzmann method, to establish a single relaxation lattice Boltzmann method is two-dimensional and three-dimensional simulation program, and the introduction of the multi-phase model of Poiseuille flow, laminar entrance flow, flow around a cylinder, the metastable phase change, the initial line source typical problem of non-steady-state diffusion simulation not only show the lattice Boltzmann method is a powerful simulation capabilities for all kinds of problems, but also to verify the effectiveness of the program. Derivation of the lattice Boltzmann method to calculate the amount of change in the estimation of changes in the relationship with the system of Reynolds number. The derivation results show that certain reasonable premise limited, simulated changes in multiples of the total number of grid points required varies with the power of multiple dimensions of the Reynolds numbers; simulate the total calculated amount of fold change in length by increasing the speed or features of the system characteristics way when the Reynolds number is increased, the second power, respectively, in accordance with the power of the dimension of the Reynolds number changes in multiple dimensions plus change. Thus the calculation of the amount of the lattice Boltzmann method is rapidly increasing with increasing Reynolds number, which limits the lattice Boltzmann method for high Reynolds number flow simulation capabilities. In order to improve the set of simulation program for high Reynolds number flow simulation capabilities, on the simulation program using OpenMP parallelization rewrite and easy for Tecplot? IJK ordered data format storage optimization method. Performance tests show that the sets of parallel programs, its parallel performance close to the ideal state: different calculation unit number under the accelerated approximate linear relationship; than meets the average parallel efficiency of 98.79%. Optimization of data storage on the storage space and processing time saving rate between 25.00% -42.86%. Two-dimensional and three-dimensional simulation of a particular phenomenon of mixed T-microchannel interface swing. 2D method can not be effective simulation of the phenomenon, which is mainly due to the role on the generation of this phenomenon, with a third spatial dimension closely linked. 3D simulation results show that this phenomenon occurs in the perpendicular to the measurement plane direction has a non-symmetrical flow structure, through the collision segment perpendicular to the measuring plane direction parallel to the collision direction of the collision velocity field within the plane of analysis found that the collision plane velocity field distribution is closely related with the the downstream mixed development segment mobility trends, further adding to the disturbance components confirmed the collision plane velocity field distribution has an important impact on the interface swing phenomenon generated.