Wavelet-based delayed detached eddy simulation method for compressible wall bounded turbulent flow modeling

2018 ◽  
Author(s):  
Xuan Ge ◽  
Oleg V. Vasilyev ◽  
M. Yousuff Hussaini
Keyword(s):  
Turbulent Flow ◽  
Simulation Method ◽  
Flow Modeling ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

Delayed Detached-Eddy Simulation and Application of a Coflow Jet Airfoil at High Angle of Attack

2013 ◽  
Vol 444-445 ◽  
pp. 270-276
Author(s):  
Wen Biao Gan ◽  
Zhou Zhou ◽  
Xiao Ping Xu ◽  
Rui Wang
Keyword(s):  
Angle Of Attack ◽  
Aircraft Design ◽  
Simulation Method ◽  
Detached Eddy Simulation ◽  
High Angle ◽  
High Angle Of Attack ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Flow Vortex ◽  
Cylinder Flow

A DDES (Delayed Detached-Eddy Simulation) method is presented and applied to simulation and design of a CFJ (Coflow Jet) airfoil at high angle of attack. The method is based on average vorticity, and is used to predict a number of test cases, including a circular cylinder flow, vortex design and simulation of the CFJ airfoil. The results demonstrate that the DDES method is efficient for CFJ airfoil flow. It provides reference to flow control and aircraft design.

Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

2017 ◽  
Vol 232 (3) ◽  
pp. 913-927 ◽  
Author(s):  
Ji-qiang Niu ◽  
Dan Zhou ◽  
Xi-feng Liang
Keyword(s):  
High Speed ◽  
Simulation Method ◽  
Aerodynamic Performance ◽  
Wake Flow ◽  
Detached Eddy Simulation ◽  
Aerodynamic Forces ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
High Speed Trains ◽  
Yaw Angle

In this study, based on the shear-stress transport κ–ω turbulent model, the improved delayed detached eddy simulation method has been used to simulate the unsteady aerodynamic performance of trains with different obstacle deflectors at two yaw angles (0° and 15°). The numerical algorithm is used and some of the numerical results are verified through wind tunnel tests. By comparing and analysing the obtained results, the effects of the obstacle deflectors on the force of the trains as well as the pressure and flow structure around the trains are elucidated. The results show that the obstacle deflectors primarily affect the flow field at the bottom of the head car as well as the wake flow, and that the internal oblique-type obstacle deflector (IOOD) markedly improves the aerodynamic performance of the trains, by decreasing most of the aerodynamic forces of the train cars and minimising their fluctuations. Further, a nonzero yaw angle weakens or even changes the effect of the IOOD on the aerodynamic forces of the train cars. However, the effect of the IOOD is more on the tail car.

Experimental Study and Detached Eddy Simulation of the Macro-Instability in an Eccentric Stirred Tank

2011 ◽  
Vol 66-68 ◽  
pp. 20-26 ◽  
Author(s):  
Feng Ling Yang ◽  
Shen Jie Zhou ◽  
Gui Chao Wang
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Simulation Method ◽  
Dominant Frequency ◽  
Diameter Ratio ◽  
Stirred Tank ◽  
Detached Eddy Simulation ◽  
Rushton Turbine ◽  
Eddy Simulation ◽  
Tank Diameter

The turbulent flow in stirred tank is highly complicated and anisotropic, especially when the macro-instability (MI) are involved. In this work, the numerical simulation method of the eccentric agitation was established based on the detached eddy simulation (DES) model to study the MI in an eccentric stirred tank. The turbulent flow in the eccentrically located Rushton turbine stirred tank was numerically investigated. The rotation of the impeller was simulated by the transient sliding mesh (SM) method. The effect of eccentricity, impeller Reynolds number and impeller-tank diameter ratio were studied in order to quantify the MI frequency. PIV experiments were performed to validate the DES results and frequency analyses were applied to the obtained time series of the velocity recordings. It was found that the flow field in eccentrically stirred tank are highly unsteady and is subject to MI with varying period less than 10 blade passage period. Good agreements have been found between the DES and PIV results, both indicate that the dominant frequency of MI increases linearly with the Reynolds number, increases with the impeller-tank diameter ratio and decreases with the eccentricity. According to the agreements between the experimental and simulation results, it can be concluded that the combination of DES and SM is suitable for the prediction of the MI phenomenon in stirred tanks.

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