| It is well-known that turbulence is a difficult problem over centuries, so does gas-solid turbulence problem. Although it has been explored by lots of scientists for more than one century, this problem has not been thoroughly solved yet. Traditionally, the numerical simulation studies of gas-solid turbulence flow are based on Reynolds-Averaged models which are not able to get accurate results. While with the rapid development of computer science, direct numerical simulation (DNS) method becomes more and more vital hotpoint. Tube bundles flow in gas-solid turbulence is typical both in nature and practical engineering. Its research not only helps us to understand the mechanism of gas-solid two phase flow, but can provide guidance for related engineering application. Under these backgrounds, this dissertation focuses on the study of DNS of gas-solid two-phase wake flow.In order to investigate the mechanism of gas-solid two-phase tube bundle flow, this dissertation adopted high accurate compact finite difference method and virtual body method to directly solve the circular cylinder wake flow in three dimensions. It includes typical arrangement of two cylinders, staggered three cylinders and in-line four cylinders flow. In the last chapter, parallel computational method was applied to simulate 5×5 in-line tube bundles flow. Before the simulation of multiple cylinders, verification was done first with the single cylinder simulation test. And the simulation results show the exact and accuracy consistent with experimental data. It clearly captured the three dimensional transitional two mode (A and B). To stimulate the particle field, Lagrange method is employed to trace the particles based on the high accurate gas-field simulation. By the qualitative and quantitative comparison of the particle dispersion with different distance between cylinders, the influence of gas flow on particle dispersion in three-dimensional circular cylinders gas-particle wake flow was investigated in detail.Flow cross two tandem cylinders was simulated under different distance between cylinders (T/d=1.2,2.0,3.0) and Reynolds number equals 250. The results of simulation shows: spanwise vortex was not captured in above-mentioned condition, because the later cylinder suppress the generation of spanwise structure. Also among three conditions, the later cylinder wake shows the same characteristic of single cylinder. But back flow of later cylinder move further with the decrease of distance between cylinders. Under different Stokes numbers, particles flow shows different distribution. For example, particles can fill vortex core when St=0.1. While large particles flow didn't show this.As for two side by side cylinders, gas-solid flow was computed with three typical distance (T/d=1.2,2.0,3.0) considered. It was clearly seen that flow pass cylinders show pseudo single vortex street(T/d=1.2); under(T/d=2.0) condition it shows asymmetrical flow and two coupled vortex street; while in the(T/d=3.0), symmetric vortex streets appear. And numerical results have the same characteristic with experimental visualization. With the influence of gas flow patterns: T/d=1.2, particle distribution represents single vortex street. T/d=2.0, gas flow have one narrow wake and wide wake which dominate particle distribution; interaction of two wake makes particle mix intensively. T/d=3.0, particle distribution is symmetric. Under different Stokes numbers, it has the same feature with tandem arrangement which particles can fill vortex core when St=0.1. But large particles can't.Staggered three cylinders and in-line four cylinders gas-solid flow was also investigated. After having carefully researched two cylinders flow, usual condition (T/d=2.0) was considered. From staggered three cylinders gas flow simulation, it is found that flow change from symetry state to asymmetric state with time development. While in-line four cylinders gas flow simulation results basically show the simply symmetry. Computational results of particle flow shows: under staggered three cylinders, the downstream cylinder was impacted dramatically, particles movement also follow gas flow which shift from one side to the other; While in-line four cylinders particles flow basically show the simply symmetry.Finally, in-line 5×5 tube bundles flow simulation was computed by blocked parallel method. Interface data exchange with D-D method to decrease error. Based on PC cluster, the parallel algoritherm was realized and practical parallel experience was introduced. Detailed tube bundles flow was investigated which includes flow development with time. And coherent structure in wake was deeply discussed. As for many vortex structures interact in downstream, it makes wake chaotic. Corresponding to simulation results, middle flow shows more regular because vortex separation from upstream tube bundles suppress the vortex generation in downstream. It is also found that middle flow basically shows interaction of multiple jet flow and wake flow, outside flow boundary was dominated by wake flow characteristic. Although two cylinders, staggered three cylinders and in-line four cylinders flow was investigated, it is not able to conclude the feature of in-line 5×5 tube bundles flow. Because whole flow was interacted with multiple jet flow and wake flow.
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