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Abe, Satoshi*; Nakayama, Hiromasa; Tamura, Tetsuro*
Dai-21-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Yoshishu (CD-ROM), 7 Pages, 2007/12
Large-eddy simulation is applied to the problem of plume dispersion in convective boundary layer (CBL) flow, which is time-sequentially generated by unsteady numerical simulation of spatially-developing boundary layer capped by a temperature inversion in the driver unit. Our objective is to investigate effects of the point source elevation on the horizontal variability of the concentration field and on the ground level concentration as function of distance from the source.
Ito, Kei; Kunugi, Tomoaki*; Yamamoto, Yoshinobu*
Dai-21-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Yoshishu (CD-ROM), 5 Pages, 2007/12
To evaluate gas entrainment phenomena in fast reactor systems accurately, we are developing a high-precision gas-liquid two-phase flow simulation method on the unstructured mesh. As a part of the development, an appropriate formulation was newly derived based on collocated variables' distributions employed in our unstructured simulation method. This formulation satisfied a mechanical balance between surface tension and pressure gradient at interfacial region. A definition formula of each phase's velocity near interfacial mesh cell was also improved to calculate physically correct velocity. The improved method was verified by simulating a rising air bubble in static water. It was confirmed that the new formulation eliminated unphysical interfacial behaviors induced by inappropriate formulations, and led similar air bubble shapes with experimental data both on the structured and the unstructured meshes.