- Wake–Structure Interactions

2012 ◽  
pp. 144-161
Keyword(s):  
Wake Structure

The effect of tail geometry on the slipstream and unsteady wake structure of high-speed trains

2017 ◽  
Vol 83 ◽  
pp. 215-230 ◽  
Author(s):  
J.R. Bell ◽  
D. Burton ◽  
M.C. Thompson ◽  
A.H. Herbst ◽  
J. Sheridan
Keyword(s):  
High Speed ◽  
Wake Structure ◽  
Unsteady Wake ◽  
High Speed Trains

scholarly journals Detailed Wake Structure behind an Elastic Airfoil

2009 ◽  
Vol 4 (2) ◽  
pp. 391-400 ◽  
Author(s):  
Masaki FUCHIWAKI ◽  
Tomoki KURINAMI ◽  
Kazuhiro TANAKA
Keyword(s):  
Wake Structure

Automotive Drag Reduction through Distributed Base Roughness Elements

2014 ◽  
Vol 553 ◽  
pp. 267-272
Author(s):  
Iain Robertson ◽  
Adrien Becot ◽  
Adrian Gaylard ◽  
Ben Thornber
Keyword(s):  
Drag Reduction ◽  
Reference Model ◽  
Detailed Examination ◽  
Rear Face ◽  
Cfd Simulations ◽  
Near Wake ◽  
Wake Structure ◽  
Pressure Drag ◽  
Roughness Elements ◽  
Baseline Case

This paper focuses on the effect of base roughness added to the rear of an automotive reference model, the Windsor model. This roughness addition was found to reduce both the drag and the lift of the model. RANS CFD simulations presented here replicate the experimentally observed drag reduction and enable a detailed examination of the mechanisms behind this effect. Investigations into the wake structure of the configurations with base roughness and the baseline case without base roughness showed the main changes to the wake to include a reduction in the overall size of the wake with base roughness present. Furthermore a reduction in the near wall velocities at the rear of the model caused stretching of the upper and lower vortices, a more turbulent near wake and pressure recovery over much of the rear face. This leads to reduce levels of pressure drag on the model.

scholarly journals A study of computational methods for wake structure and base pressure prediction of a generic SUV model with fixed and rotating wheels

2017 ◽  
Vol 231 (9) ◽  
pp. 1222-1238 ◽  
Author(s):  
David Forbes ◽  
Gary Page ◽  
Martin Passmore ◽  
Adrian Gaylard
Keyword(s):  
Experimental Data ◽  
Computational Methods ◽  
Large Scale ◽  
Ground Plane ◽  
Computational Cost ◽  
Rear Wheel ◽  
Base Pressure ◽  
Detached Eddy Simulation ◽  
Wake Structure ◽  
Wake Interactions

This study is an evaluation of the computational methods in reproducing experimental data for a generic sports utility vehicle (SUV) geometry and an assessment on the influence of fixed and rotating wheels for this geometry. Initially, comparisons are made in the wake structure and base pressures between several CFD codes and experimental data. It was shown that steady-state RANS methods are unsuitable for this geometry due to a large scale unsteadiness in the wake caused by separation at the sharp trailing edge and rear wheel wake interactions. unsteady RANS (URANS) offered no improvements in wake prediction despite a significant increase in computational cost. The detached-eddy simulation (DES) and Lattice–Boltzmann methods showed the best agreement with the experimental results in both the wake structure and base pressure, with LBM running in approximately a fifth of the time for DES. The study then continues by analysing the influence of rotating wheels and a moving ground plane over a fixed wheel and ground plane arrangement. The introduction of wheel rotation and a moving ground was shown to increase the base pressure and reduce the drag acting on the vehicle when compared to the fixed case. However, when compared to the experimental standoff case, variations in drag and lift coefficients were minimal but misleading, as significant variations to the surface pressures were present.

Computational Study of the Wake Structure of a Simplified Ground-vehicle Shape with Base Slant

1989 ◽  
Author(s):  
Masanori Hashiguchi ◽  
Kenji Kawaguchi ◽  
Ryuuichi Yamasaki ◽  
Kunio Kuwahara
Keyword(s):  
Computational Study ◽  
Wake Structure ◽  
Ground Vehicle ◽  
Vehicle Shape

Effect of Channel Inlet Blockage on the Wake Structure of a Rotationally Oscillating Cylinder

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
S. Kumar
Keyword(s):  
Mode Shape ◽  
Channel Wall ◽  
Shape Change ◽  
Vortex Street ◽  
Channel Width ◽  
Channel Inlet ◽  
Oscillating Cylinder ◽  
Wake Structure ◽  
Freestream Velocity ◽  
Cylinder Diameter

This paper investigates, experimentally for the first time, the effect of channel inlet blockage induced by bringing the channel inlet walls closer together on the wake structure of a rotationally oscillating cylinder. The cylinder is placed symmetrically inside the channel inlet. The Reynolds number (based on constant upstream channel inlet freestream velocity) is 185, and three channel wall spacings of two, four, and eight cylinder diameters are used. Cylinder oscillation amplitudes vary from π/8 to π, and normalized forcing frequencies vary from 0 to 5. The diagnostics is done using hydrogen-bubble flow visualization, hot-wire anemometry, and particle image velocimetry (PIV). It is found that rotational oscillations induce inverted-vortex-street formation at channel width of two cylinder diameter where there is no shedding in unforced case. The channel wall boundary layers at this spacing undergo vortex-induced instability due to vortex shedding from cylinders and influence the mechanism of inverted-vortex-street formation near the cylinder. At channel width of four cylinder diameter, the inverted-vortex-street is still present but the mode shape change seen at normalized forcing frequency of 1.0 in the absence of channel walls is delayed due to the presence of nearby walls. The wake structure is observed to resemble the wake structure in unbounded domain case at channel width of eight cylinder diameter with some effect of channel walls on forcing parameters where mode shape change occurs. The lock-on diagram is influenced by the closeness of the channel walls, with low-frequency boundary moving to lower frequencies at smallest channel width.

A Study on Wake Structure of Soccer Ball

2007 ◽  
Author(s):  
T Asai ◽  
O Kobayashi ◽  
K Seo ◽  
R Sakashita
Keyword(s):  
Wake Structure ◽  
Soccer Ball

scholarly journals Field investigation of a wake structure downwind of a VAWT in a windfarm array

1987 ◽  
Author(s):  
H.T. Liu ◽  
J.W. Buck ◽  
A.C. Germain ◽  
M.E. Hinchee ◽  
T.S. Solt ◽  
...  
Keyword(s):  
Field Investigation ◽  
Wake Structure
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