Large eddy simulation of bluff body flames close to blow-off using an Eulerian stochastic field method

Unsteady Large Eddy Simulation (LES) is carried out for the flow around a bluff body equipped with an underbody rear diffuser in close proximity to the ground, representing an automotive diffuser. The goal is to demonstrate the ability of LES to model underbody vortical flow features at experimental Reynolds numbers (1.01 × 106 based on model height and incoming velocity). The scope of the time-dependent simulations is not to improve on Reynolds-Averaged Navier Stokes (RANS), but to give further insight into vortex formation and progression, allowing better understanding of the flow, hence allowing more control. Vortical flow structures in the diffuser region, along the sides and top surface of the bluff body are successfully modelled. Differences between instantaneous and time-averaged flow structures are presented and explained. Comparisons to pressure measurements from wind tunnel experiments on an identical bluff body model shows a good level of agreement.

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A Large-Eddy-Simulation Study of Combustion Dynamics of Bluff-Body Stabilized Flames

Combustion Science and Technology ◽

10.1080/00102202.2015.1136296 ◽

2016 ◽

Vol 188 (6) ◽

pp. 924-952 ◽

Cited By ~ 17

Author(s):

Hua-Guang Li ◽

Prashant Khare ◽

Hong-Gye Sung ◽

Vigor Yang

Keyword(s):

Large Eddy Simulation ◽

Simulation Study ◽

Bluff Body ◽

Combustion Dynamics ◽

Eddy Simulation ◽

Large Eddy ◽

Stabilized Flames

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Very Large Eddy Simulation of Passive Drag Control for a D-Shaped Cylinder

Journal of Fluids Engineering ◽

10.1115/1.4024654 ◽

2013 ◽

Vol 135 (10) ◽

Cited By ~ 8

Author(s):

Xingsi Han ◽

Siniša Krajnović

Keyword(s):

Large Eddy Simulation ◽

Flow Control ◽

Control Problem ◽

Bluff Body ◽

Numerical Study ◽

Numerical Results ◽

Complex Flow ◽

Local Disturbance ◽

Eddy Simulation ◽

Large Eddy

The numerical study reported here deals with the passive flow control around a two-dimensional D-shaped bluff body at a Reynolds number of Re=3.6×104. A small circular control cylinder located in the near wake behind the main bluff body is employed as a local disturbance of the shear layer and the wake. 3D simulations are carried out using a newly developed very large eddy simulation (VLES) method, based on the standard k − ε turbulence model. The aim of this study is to validate the performance of this method for the complex flow control problem. Numerical results are compared with available experimental data, including global flow parameters and velocity profiles. Good agreements are observed. Numerical results suggest that the bubble recirculation length is increased by about 36% by the local disturbance of the small cylinder, which compares well to the experimental observations in which the length is increased by about 38%. A drag reduction of about 18% is observed in the VLES simulation, which is quite close to the experimental value of 17.5%. It is found that the VLES method is able to predict the flow control problem quite well.

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