The Numerical Simulation Of Wind Loads On Simplified Model Of Low-rise Building By Lattice Boltzmann Method

The damage caused by wind loads accounts for the most of which caused by various natural disasters, among which the loss of low-rise building destruction or collapse is more than half, thus, it is particularly important to study the wind pressure of low-rise building. Because of its unique advantages, the computational wind engineering should be the trend of recent wind engineering research. Looking for a more efficient numerical simulation method has practical significance. In this paper, the lattice Boltzmann method(LBM) is applied to simulate the wind loads on simplified model of low-rise building by developing C++ program independently.In the paper, the traditional LBM is optimized: The incompressible lattice Boltzmann model is introduced which can simulate the fluid flow of atmospheric boundary layer more realistically. Besides, the multiple-relaxation-time model is proposed for high Reynolds number wind field with better numerical stability instead of the single-relaxation-time model. In addition, large eddy simulation is introduced to simulate the large scale vortex directly, while the influence of small scale vortex on large scale vortex is reflected through the subgrid Reynolds stress. And it is feasible to shorten the computing time through parallel processing. Predecessors usually consider a certain kind of optimization method, while this paper firstly considers all of these optimization methods simultaneously in order to reflect the actual flow field better.The two-dimensional flow around cylinder is introduced and these flow field parameters of a number of Reynolds number are calculated such as pressure coefficient. The rusults of the flow around a two-dimensional cylinder are compared with the past simulation results and experimental datas. The comparison demonstrates the simulation of pressure with the LBM is feasible. Furthermore, compared with the single-relaxation-time model, the method based on the multiple-relaxation-time LBM shows better accuracy in simulating the fluid flow.In order to solve the curve boundary treatment of gable roof in low rise buildings, a gable roof curve boundary processing parameter is deduced and an immersed boundary is adopted into the LBM successfully. Thus, the simulation accuracy of the gable roof is improved effectively.Finally, the optimized LBM is applied to simulate the two-dimensional wind field of simplified low-rise building model and analyze the evolution process of the vortex shedding around the building and calculate the wind pressure on low-rise building for the first time. The results of area-averaged wind pressure coefficient are compared with the data obtained from the load coad. Although the area-averaged wind pressure coefficient calculated by LBM fluctuates around the specification value, the overall trend is basically the same, which confirms that LBM is more accurate and feasible to analyze the wind pressure of low-rise building. The lattice Boltzmann method has many advantages, such as its fast speed of solution, high degree of parallelism, as well as its reliable calculation results, thus, it is likely to become an effective method of simulating the wind loads on low-rise building.