Drag reduction for (a) spanwise oscillation cases
Turbulent Drag Reduction by Spanwise Wall Oscillations
... W = π , as suggested by [1]. Here, Q is the volumetric flow rate per unit width in the streamwise direction. The oscillation frequency f + is set to be 0.01, corresponding to T + osci = 100 considered by [1] and ...
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Turbulent skin friction drag reduction control by spanwise motion
... skin-friction drag reduction with Direct Numerical ...understand drag reduction mechanism in simple spanwise wall oscillation case (Jung et ...2% drag reduction was ...
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Streamwise-Travelling Waves of Spanwise Wall Velocity for Turbulent Drag Reduction
... DI cases, the value of q is changed so as to always yield q + = −4 when computed with the actual friction velocity of the ...local spanwise velocity component at the ...
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A numerical study of turbulent drag reduction using streamwise travelling waves of spanwise wall velocity
... few cases were also performed up to Re τ = 2100. It was found that the drag reduction decreases with increased Re, and that the rate of decrease is heavily dependent on the control ...high ...
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Wall oscillation induced drag reduction zone in a turbulent boundary layer
... 29, 41 (2004)]. The downstream development of DR in the numerical simula- tion and experiment is nearly identical. The velocity profiles and the indicator function are investigated with respect to the variation in DR and ...
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Turbulent skin-friction drag deduction via spanwise wall oscillations
... the drag reduction deteriorates at increasing Re has been investigated in Chapter ...of spanwise wall velocity, a generalization of the spanwise wall oscillations, has been chosen as model ...
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Drag Reduction by Laminar Flow Control
... the drag coefficient of a turbulent fuselage as a baseline for the evaluation of ...of drag reduction due to the delay of transition, preserving the laminar boundary ...the cases simulated, ...
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Drag Reduction in Oil-water Flows
... While the profile is symmetric for only water flows, when polymer is present large velocity gradients appear at the lower part of the pipe compared to the upper one. This region resembles the thickened buffer layer ...
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A mechanistic model of turbulent drag reduction by additives
... solution drag reducing flows (as those in Sec- tion 3) demonstrates t/(2t R ) < 1, meaning that their dominant eddy oscillation periodical time is smaller than their polymer relaxation ...
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Turbulent drag reduction through oscillating discs
... sustained reduction of wall-shear stress, which reaches a maximum of ...and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag ...
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Mini Spoilers for Afterbody Base Drag Reduction
... and 5% heights resulted in drag reductions of 4.5% and 4.8% respectively, and this was attributed to the increase in surface pressure ahead of the spoiler. The resulting time-averaged vortex was moved further away ...
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Numerical Drag Reduction Studies on Generic Truck
... of drag was found to be lower than the experimental ...while spanwise two-dimensional vortex structures occured at the back edges of the Ahmed body similar to the wake structures generated by the 2-D ...
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Turbulent drag reduction using surface plasma
... An oscillation period of T + = 100 was used with different vortex strengths and sizes and it was observed that the spanwise cross flow caused by the wall oscillation deforms and leads to a mutual ...
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Turbulent drag reduction through wall-forcing methods
... ∆t ˆ imodulo “ 1.25. Therefore the fields are saved every t “ 1.25 which is equivalent to 10ν ˚ {u ˚2 τ,r . A checkpoint file is also generated in the case of any unexpected behaviour from the code. This file is saved at ...
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Computational investigation of drag reduction on a rotationally oscillating cylinder
... large drag reduction experimentally observed for the ...rotational oscillation found in the ...but drag reduction still results from control with amplitudes and frequencies that ...
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The Laminar Generalized Stokes Layer and Turbulent Drag Reduction
... of spanwise velocity applied at the wall and travelling along the streamwise ...the spanwise flow induced by the ...turbulent spanwise flow, provided that the phase speed of the waves is sufficiently ...
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Reduction Of Drag Forces Of An Aircraft
... the drag forces by ...reduced drag effects and a retractable ...the reduction of drag forces by employing a number of methods have been discussed in this paper ...2-3% reduction in ...
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Review on Aerodynamic Drag Reduction of Vehicles
... underbody drag reduction devices like undercover, under- fin, and side air dam on the actual shape of a sedan-type vehicle [53], among these underbody has the ability to reduce the aerodynamic drag ...
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Aerodynamic Drag Reduction of Emergency Response Vehicles
... additional drag that results from the customary practice of adding light-bars onto the vehicles’ ...in drag that results from the light bars and show these can be minimized by reducing the flow separation ...
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Drag reduction in pipe flows with polymer additives
... This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For ...
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