| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
The purpose of this study is to newly develop an algebraic stress model (ASM) and to establish the efficient numerical scheme for solving the fundamental equations of incompressible flow in curvilinear coordinate, in order to perform the numerical analysis of turbulent flow of engineering interest in high Reynolds number using the practical timeaveraged turbulence model.
First, to overcome the defect of ASM used previously, the algebraic representation for the Reynolds stress was derived to express the anisotropy mainly appeared in turbulent shear flow, the isotropization and the decaying process in free turbulent flow, so that the new ASM has been proposed. In this derivation, the algebraic procedure of the transport term was followed based on the transport equation for the Reynolds stress. As a result, it becomes clear that the term including the history effect on the Reynolds stress plays an important role. In the present model, therefore, such a defect of the previous model that the
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non-physical solution giving the instantaneous isotropization for the anisotropic turbulence without shear is inevitably resulted in, has been dissolved by taking account of the history term. Next, to clarify the validity of the present model, the verification was made using the reliable data-base for the homogeneous anisotropic turbulence obtained by the direct numerical simulation. It is indicated that the time evolution of the Reynolds stress can be predicted well, especially the Reynolds shear stress which has not yet been predicted even qualitatively by the previous model can be reproduced very well by the present model. The useful knowledge related to the history effect was obtained and a guide to computation of complex turbulent flow field was able to be provided.
On the other hand, the implicit SMAC scheme using the curvilinear coordinate grid, which has been developed by the present researchers, was extended to apply to unsteady 3-D flow. Performing the large-scale numerical simulation beyond a million grid points, the structure of unsteady flow through 3-D backward-facing step duct was clarified. And the present scheme is verified to be compatible and efficient one as a computational code for the turbulent flow analysis. Less
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