Three-dimensional aspects of cylinder drag reduction by suction and oscillatory blowing

AbstractWith the rapid development of science and technology, increasing research interests have been focused on environment protection, global warming, and energy shortage. At present, reducing friction force as much as possible has developed into an urgent issue. Sharkskin effect has the potential ability to lower viscous drag on the fluid-solid interface in turbulence, and therefore, how to fabricate bio-inspired sharkskin surfaces is progressively becoming the hot topic. In this review, various methods of fabricating drag reduction surfaces covering biological sharkskin morphology are illustrated and discussed systematically, mainly involving direct bio-replicated, synthetic fabricating, bio/micro-rolling, enlarged solvent-swelling, drag reduction additive low-releasing, trans-scale enlarged three-dimensional fabricating, flexible printing, large-proportional shrunken bio-replicating, ultraviolet (UV) curable painting, and stretching deformed methods. The overview has the potential benefits in better acquainting with the recent research status of fabricating sharkskin surfaces covering the biological morphology.

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The Effect of Single Dielectric Barrier Discharge Actuators in Reducing Drag on an Ahmed Body

Fluids ◽

10.3390/fluids5040244 ◽

2020 ◽

Vol 5 (4) ◽

pp. 244

Author(s):

Saber Karimi ◽

Arash Zargar ◽

Mahmoud Mani ◽

Arman Hemmati

Keyword(s):

Drag Reduction ◽

Dielectric Barrier Discharge ◽

Barrier Discharge ◽

Three Dimensional ◽

Reynolds Numbers ◽

Aerodynamic Performance ◽

Dielectric Barrier ◽

Car Model ◽

Slant Surface ◽

Ahmed Body

The feasibility of a single dielectric barrier discharge (SDBD) actuator in controlling flow over an Ahmed body, representing a simplified car model, has been numerically and experimentally investigated at Reynolds numbers of 7.68×105 and 2.25×105. The Ahmed body had slant angles of 25∘ and 35∘. The results showed that SDBD actuators could significantly enhance the aerodynamic performance of the Ahmed body. Several arrangements of the actuators on the slant surface and the rear face of the model were examined to identify the most effective arrangement for drag reduction. This arrangement resulted in an approximately 6.1% drag reduction. This improvement in aerodynamic performance is attributed to the alteration of three-dimensional wake structures due to the presence of SDBD, which coincides with surface pressure variations on the slant and rear faces of the Ahmed body.

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Unsteady Aerodynamic Flow Investigation Around a Simplified Square-Back Road Vehicle With Drag Reduction Devices

Journal of Fluids Engineering ◽

10.1115/1.4006643 ◽

2012 ◽

Vol 134 (6) ◽

Cited By ~ 24

Author(s):

Bahram Khalighi ◽

Kuo-Huey Chen ◽

G. Iaccarino

Keyword(s):

Drag Reduction ◽

Three Dimensional ◽

Common Element ◽

Road Vehicle ◽

Flow Investigation ◽

Upward Deflection ◽

Unsteady Rans ◽

The Common ◽

Shedding Frequency ◽

Coanda Jet

The unsteady flow around a simplified road vehicle model with and without drag reduction devices is investigated. The simulations are carried out using the unsteady RANS in conjunction with the v2-f turbulence model. The corresponding experiments are performed in a small wind tunnel which includes pressure and velocity fields measurements. The devices are add-on geometry parts (a box with a cavity and, boat-tail without a cavity) which are attached to the back of the square-back model to improve the pressure recovery and reduce the flow unsteadiness. The results show that the recirculation regions at the base are shortened and weakened and the base pressure is significantly increased by the devices which lead to lower drag coefficients (up to 30% reduction in drag). Also, the results indicate a reduction of the turbulence intensities in the wake as well as a rapid upward deflection of the underbody flow with the devices in place. A reduction of the unsteadiness is the common element of the devices studied. The baseline configuration (square-back) exhibits strong three-dimensional flapping of the wake. The main shedding frequency captured agrees well with the available experimental data. Comparisons with the measurements show that the simulations agree reasonably well with the experiments in terms of drag and the flow structures. Finally, a blowing system (Coanda jet) is investigated numerically. In this case a drag reduction of up to 50% is realized.

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Direct Numerical Simulation of Flow around a Circular Cylinder Controlled Using Plasma Actuators

Mathematical Problems in Engineering ◽

10.1155/2014/591807 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 5

Author(s):

Taichi Igarashi ◽

Hiroshi Naito ◽

Koji Fukagata

Keyword(s):

Numerical Simulation ◽

Circular Cylinder ◽

Direct Numerical Simulation ◽

Drag Reduction ◽

Three Dimensional ◽

Reduction Rate ◽

Plasma Actuators ◽

Two Dimensional ◽

Freestream Velocity ◽

The Mean

Flow around a circular cylinder controlled using plasma actuators is investigated by means of direct numerical simulation (DNS). The Reynolds number based on the freestream velocity and the cylinder diameter is set atReD=1000. The plasma actuators are placed at±90° from the front stagnation point. Two types of forcing, that is, two-dimensional forcing and three-dimensional forcing, are examined and the effects of the forcing amplitude and the arrangement of plasma actuators are studied. The simulation results suggest that the two-dimensional forcing is primarily effective in drag reduction. When the forcing amplitude is higher, the mean drag and the lift fluctuations are suppressed more significantly. In contrast, the three-dimensional forcing is found to be quite effective in reduction of the lift fluctuations too. This is mainly due to a desynchronization of vortex shedding. Although the drag reduction rate of the three-dimensional forcing is slightly lower than that of the two-dimensional forcing, considering the power required for the forcing, the three-dimensional forcing is about twice more efficient.

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Circular cylinder drag reduction using piezoelectric actuators

Advances in aircraft and spacecraft science ◽

10.12989/aas.2014.1.1.027 ◽

2014 ◽

Vol 1 (1) ◽

pp. 27-41 ◽

Cited By ~ 2

Author(s):

Matteo Orazi ◽

Davide Lasagna ◽

Gaetano Iuso

Keyword(s):

Circular Cylinder ◽

Drag Reduction ◽

Piezoelectric Actuators ◽

Cylinder Drag

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Effect of the Lorentz force on cylinder drag reduction and its optimal location

Fluid Dynamics Research ◽

10.1088/0169-5983/43/1/015506 ◽

2010 ◽

Vol 43 (1) ◽

pp. 015506 ◽

Cited By ~ 10

Author(s):

Hui Zhang ◽

Bao-chun Fan ◽

Zhi-hua Chen ◽

Yan-ling Li

Keyword(s):

Drag Reduction ◽

Lorentz Force ◽

Optimal Location ◽

Cylinder Drag

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Drag reduction and wear resistance mechanisms of a bionic shovel by discrete element method simulation

SIMULATION ◽

10.1177/0037549718784658 ◽

2018 ◽

Vol 95 (3) ◽

pp. 231-239 ◽

Cited By ~ 3

Author(s):

Rui Zhang ◽

Dianlei Han ◽

Yuan He ◽

Haijin Wan ◽

Songsong Ma ◽

...

Keyword(s):

Discrete Element Method ◽

Drag Reduction ◽

High Speed ◽

Three Dimensional ◽

Discrete Element ◽

Resistance Mechanisms ◽

Fatigue Wear ◽

Soil Particles ◽

The Common ◽

Element Method

The ostrich has a steady and enduring high-speed running ability. Toenails are one key part of ostrich feet and their unique morphology is crucial in insertion into sand and for traction provision. In this study, information of bionic curves was extracted through studying the toenail structure and morphology, and three-dimensional reconstruction of toenails by reverse engineering. Based on the principle of bionic engineering, a bionic shovel was designed by optimizing the traditional shovel. A shovel–soil interaction mechanical model was established via the discrete element method. The insertion into soil processes of the bionic shovel and the common plate were simulated. The dynamic mesoscopic mechanical behaviors of soil particles around the shovel surface, the contact force field, and the velocity field, as well as the forces acting on the shovel surface were analyzed. The bionic shovel outperformed the common plate in insertion. The main reason for drag reduction in the bionic shovel was the inner concave bending surface, along which the soil particles climbed, and the particle movement trend was consistent. Simulations showed stress concentrated at the tip of the shovel, which facilitated the production of fatigue wear. Therefore, the tip needs to be considered firstly during bionic shovel design in the future.

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The Simulation Research on Air Drag Reduction of Tail Dome on Vans

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.345.48 ◽

2013 ◽

Vol 345 ◽

pp. 48-53

Author(s):

Li Feng Cao ◽

Xiao Peng Xie ◽

Jian Hao Zeng ◽

Heng Huang

Keyword(s):

Drag Reduction ◽

Cfd Simulation ◽

Three Dimensional ◽

Test Results ◽

Three Dimensional Model ◽

Simulation Test ◽

Simulation Research ◽

Wind Resistance ◽

Pressure Drag ◽

Variable Speed Motor

In this paper, three different types of tail domes were designed based on the mechanism of reducing pressure drag between the front and rear of vans, and it takes the van without a dome as a comparison to discuss the drag reduction effects of three different sizes. The three-dimensional model of the van is established in PRO/E, and the pressure and velocity distribution of the van model were analyzed in Fluent; In addition, the wind resistance test of the van model is proceed in the variable speed motor wind resistance simulation test device. The results of CFD simulation have good consistency with the experimental test results, and it verifies the conclusion that the tail dome is good for drag reduction. It provides basis and reference for the optimization of drag reduction for the vans.

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