2004 Fiscal Year Final Research Report Summary
Dynamic SGS modeling for LES with SGS diffusion effect on GS turbulent field
| Project/Area Number |
14550148
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Nagoya Institute of Technology |
|---|
Principal Investigator |
MORINISHI Youhei Nagoya Institute of Technology, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (40222351)
|
|---|
| Project Period (FY) |
2002 – 2004
|
| Keywords | LES / SGS model / SGS stress / DNS / plane channel flow / A priori test |
|---|
| Research Abstract |
This study was aimed for constructing a subgrid scale(SGS) model which takes the SGS diffusion effect, on the grid scale(GS) flow field of large eddy simulation(LES) of turbulent flow.
First of all, direct numerical simulation(DNS) of the plane channel flow with passive scalar transport was performed at the Reynolds number 300 based on the friction velocity and channel half width. The GS and SGS statistics corresponding to the two-and three-dimensional filters were computed using the DNS flow field. The data were used in the following SGS modeling study. In addition, the effect of the different thermal wall boundary conditions on the turbulence statistics of the plane channel flow was estimated using the constructed DNS data.
Secondly, the wall asymptotic behavior of the SGS stress was considered. The SGS stress computed from the DNS data were compared with the analytical result, derived from Taylor expansion, and its wall asymptotic behaviors were specified for both two-and three-dimensional filters.
Finally, the SGS model with the transport equation of the SGS kinetic energy was considered to take the SGS diffusion effect on the GS flow field of LES. Existing one-equation type SGS models assume the gradient diffusion assumption for the SGS diffusion term and introduce an assumption based on a turbulence statistical theory for the SGS dissipation term. However, these models were less correlated with the exact terms. In this study, the SGS models based on the scale similarity assumption for the SGS diffusion and dissipation terms were tested a priori using the DNS data of the plane channel flow. Then, a mixed model for the SGS diffusion and dissipation terms were proposed as a result of this study.
|
