| Research Abstract |
Gas/particle two-phase turbulent flow can be observed in a great number of machines, and thus this flow is very important in engineering fields. In addition, with increasing the attention to the environmental problems, the importance of this flow has been focused on, recently. Considering these backgrounds, the present research has been carried out to develop a Reynolds stress model that can predict the anisotropy of particle-phase turbulence.
In 2000, based on the DNS, LES and experimental data, the characteristics of particle-phase turbulence were investigated. And taking into account the anisotropic modeling of single-phase turbulence, a new model for reproducing the anisotropy of particle-phase turbulence was proposed. LRR model for single-phase flow was selected as the basic model. Using the model, the 2 dimensional channel flow was verified, and the performance of the model for nearly isotropic turbulence was clarified.
In 2001, the present model was extensively verified. The first case was the highly-swirling flow in a cyclone separator. Comparing the numerical results obtained by our model and the measured data, it was exhibited that the anisotropy of particle-phase turbulence does not affect the mean flow field so strongly because of the relatively low concentration. As the second case, micro-bubble turbulent flow was studied. Applying the present model to the flow, it was confirmed that the anisotropy of bubble-phase is the key factor to simulate the phenomena, our model can predict the peak and the downstream change, and the performance has to be improved to predict the near wall phenomena more exactly.
In this project, we developed a new Reynolds stress model that can reproduce the anisotropy of fluid- and particle-phase turbulence. In the near future, we are planning to refine the present model through more extensive verifications
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