Drafting kissing and tumbling process of two particles参考.ppt

Drafting, kissing and tumbling process of two particles Liang Wang National Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China 9th International Conference for Mesoscopic Methods in Engineering and Science 23-27, July Outline Introduction Probelm description and Code Validation Numerical results Summary Introduction Drafting, Kissing and tumbling (DKT) process Two particles with uniform sizes Two particles with different sizes ??? DKT process of two particles Two identical particles Two nonidentical partices partilce size particle density surface properities Two diffrent configurations Present work The sedimentation process of two particles is significant by a number of intrinsic factors, such as particle density, shape and surface properities. But in most cases, the paticle size plays the dominant role in the real engineering applications. Inlet: outlet Moving computational domain Case1 Case 0 Diameter ratio γ Probelm description and Code Validation Case 2 MRT-based computaions Reproduce the DKT phenomenon Transverse coordinates of two particles Longitudinal coordinates of two particles Good aggrement with previous results can be seen up to the kissing stage, and the post-collision qualitative behaviour of the particles is identical. Code valiation Three distances bwtween two particles The three distances between two particles can be used to analyze the DKT process. The difference of transverse coordinates longitudinal coordinates The gap between two particles Numerical results The two identical particles undergo repeated DKT process. The two nonidentical particles undergo DKT process only once . The smaller particle always keeps to be above the larger one during the DKT process The pressure aroud two particles The drag coefficient of the trailing particle in case-0 is smaller than that in case-1 and case-2, and the drag coefficient of the leading particle is larger