A Study on Inlet Turbulence Information for Large Eddy Simulation

2014 ◽  
Vol 638-640 ◽  
pp. 1763-1768
Author(s):  
Lian Shen ◽  
Guo Chao Dong ◽  
Yan Han ◽  
Chun Sheng Cai ◽  
Chun Guang Li

In view of the question that the inlet boundary conditions of turbulence information for the large eddy simulation process is difficult to be settled, the target wind field was divided into blocks along the height direction firstly. Under the assumption of the same height and its nearby area, fluctuating wind field characteristics are the same, the one-to-one relationship between time-history data and the target area was established, using the classical WAWS to simulate the fluctuating time-history data of wind field. Then the time-history data were given to the homologous grid of the target wind field during the process of large eddy simulation, and fluctuating information of the large eddy simulation in the whole entrance was obtained consequently. Finally, a secondary development of the commercial software FLUENT was proceeding, and a simulation of the flow field without any obstacles was established. The fluctuating time-history data were written in by using the method presented in this thesis, and the entrance boundary conditions were generated. By analyzing the wind field’s power spectrum and correlation at different positions, we find that the wind field generated by the method presented in the paper can satisfy the basic characteristic of the fluctuating wind field, and it also provides references for the refine research of the large eddy simulation boundary conditions.

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Puxuan Li ◽  
Steve J. Eckels ◽  
Garrett W. Mann ◽  
Ning Zhang

The setup of inlet conditions for a large eddy simulation (LES) is a complex and important problem. Normally, there are two methods to generate the inlet conditions for LES, i.e., synthesized turbulence methods and precursor simulation methods. This study presents a new method for determining inlet boundary conditions of LES using particle image velocimetry (PIV). LES shows sensitivity to inlet boundary conditions in the developing region, and this effect can even extend into the fully developed region of the flow. Two kinds of boundary conditions generated from PIV data, i.e., steady spatial distributed inlet (SSDI) and unsteady spatial distributed inlet (USDI), are studied. PIV provides valuable field measurement, but special care is needed to estimate turbulent kinetic energy and turbulent dissipation rate for SSDI. Correlation coefficients are used to analyze the autocorrelation of the PIV data. Different boundary conditions have different influences on LES, and their advantages and disadvantages for turbulence prediction and static pressure prediction are discussed in the paper. Two kinds of LES with different subgrid turbulence models are evaluated: namely dynamic Smagorinsky–Lilly model (Lilly model) and wall modeled large eddy simulation (WMLES model). The performances of these models for flow prediction in a square duct are presented. Furthermore, the LES results are compared with PIV measurement results and Reynolds-stress model (RSM) results at a downstream location for validation.


2001 ◽  
Vol 446 ◽  
pp. 309-320 ◽  
Author(s):  
IVAN MARUSIC ◽  
GARY J. KUNKEL ◽  
FERNANDO PORTÉ-AGEL

An experimental investigation was conducted to study the wall boundary condition for large-eddy simulation (LES) of a turbulent boundary layer at Rθ = 3500. Most boundary condition formulations for LES require the specification of the instantaneous filtered wall shear stress field based upon the filtered velocity field at the closest grid point above the wall. Three conventional boundary conditions are tested using simultaneously obtained filtered wall shear stress and streamwise and wall-normal velocities, at locations nominally within the log region of the flow. This was done using arrays of hot-film sensors and X-wire probes. The results indicate that models based on streamwise velocity perform better than those using the wall-normal velocity, but overall significant discrepancies were found for all three models. A new model is proposed which gives better agreement with the shear stress measured at the wall. The new model is also based on the streamwise velocity but is formulated so as to be consistent with ‘outer-flow’ scaling similarity of the streamwise velocity spectra. It is therefore expected to be more generally applicable over a larger range of Reynolds numbers at any first-grid position within the log region of the boundary layer.


2008 ◽  
Vol 42 (6) ◽  
pp. 1083-1097 ◽  
Author(s):  
R.F. Shi ◽  
G.X. Cui ◽  
Z.S. Wang ◽  
C.X. Xu ◽  
Z.S. Zhang

Sign in / Sign up

Export Citation Format

Share Document