Project/Area Number  10440028 
Research Category 
GrantinAid for Scientific Research (B).

Section  一般 
Research Field 
General mathematics (including Probability theory/Statistical mathematics)

Research Institution  Nagoya University 
Principal Investigator 
ISHII Katsuya Nagoya University, Graduate School of Engineering, Assoc. Prof., 工学研究科, 助教授 (60134441)

CoInvestigator(Kenkyūbuntansha) 
OHARA Yoshio Graduate School of Engineering, Assistant, 工学研究科, 助手 (20023294)
ISHIHARA Takashi Graduate School of Engineering, Assistant, 工学研究科, 助手 (10262495)
KANEDA Yukio Graduate School of Engineering, Prof., 工学研究科, 教授 (10107691)

Project Fiscal Year 
1998 – 1999

Project Status 
Completed(Fiscal Year 1999)

Budget Amount *help 
¥8,500,000 (Direct Cost : ¥8,500,000)
Fiscal Year 1999 : ¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1998 : ¥5,100,000 (Direct Cost : ¥5,100,000)

Keywords  3dimensional free boundary condition / Two phase fluid / Level set method / no reflective boundary condition / vortex motion / acoustic wave / combined compact scheme / high resolution / 三次元自由境界条件 / 二相流体 / レベルセット法 / 無反射境界条件 / 渦運動 / 音波 / 結合コンパクトスキーム / 高精度 / 気泡 / 自由境界条件 
Research Abstract 
The Purpose of this study is to develop high accurate numerical schemes for the fluid flow by using the accurate boundary conditions. For the simulation of the fluid flow, the adequate choice of numerical boundaries and/or interfaces is needed. We considered three numerical problems : (A) the fluid flow with three dimensional free surface or interface, (B) the boundary conditions of the vortical flow field interacting with acoustic waves, and (c) the boundary conditions of the vortical flow field interacting with acoustic waves. and (c) the boundary conditions for the scheme with accuracy and high resolutions. The results of the study are as follows : (1) The level set formulation for the interface of twophase fluids is developed in the threedimensional incompressible flow calculations, including large density and viscosity ratio as well as surface tension effects. Numerical simulations carried out for two rising gas bubbles, the interaction of buoyant drops with a fluidfluid interfa
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ce, and the propagation of surface waves. The results agree with previous experiment data, and make it possible to analyze the physical quantities near the boundaries. (2) Improving the boundary conditions for the vector velocity potential, we get the accurate numerical method for the localized vorticity fields. Using this method, the vortex sounds can be evaluated in the various flow fields, and the sound generation mechanism can be analyzed. (3) Using the no reflective boundary conditions, the acoustic control of flow separation at low Reynolds numbers are studied. We reproduced the phenomena that the tendency toward the separation on an airfoil is reduced by an acoustic excitation, and analyze the detailed flow field near the point of separation. (4) The combined compact scheme with high accuracy and high resolution is developed in the generalized grid system with concentrated points near the boundary. This scheme gives more accurate numerical results compared with the other finite difference methods. (5)熱塩対流や回転剪断流などを含む、様々な乱流の直接計算を実行し、理論との比較、モデルの検証などを行った。 Less
