Integral force acting on a body due to local flow structures

Wu, Jing; Lu, Xi‐Yun; Zhuang, Lixian

doi:10.1017/s0022112006004551

Cited by 150 publications

(76 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(17). The term due to the open control surface (19) contributes approximately half the total drag force for high-Reynolds-number flow, consistent with the result for viscous flow around a circular cylinder [24].…”

Section: Force Behaviorssupporting

confidence: 84%

“…To understand the mechanisms underlying the compressible flow past the cylinders, the force expression based on derivative-moment transformations [23,24] is used to analyze the drag-force contributions. Let f V be a 3D compressible fluid domain surrounding a rigid and stationary body, B, and bounded externally by an arbitrary control surface,  , then the force formulation in terms of the resolved variables is expressed as [23]…”

Section: Force Behaviorsmentioning

confidence: 99%

“…(17) degenerates to the boundary vorticity flux based force expression for an open body surface [24]. According to the analysis of force decomposition [23], the terms in eq.…”

Section: Force Behaviorsmentioning

confidence: 99%

See 2 more Smart Citations

Large-eddy simulation of the compressible flow past a tabbed cylinder

Zhao

Sun

2012

Chin. Sci. Bull.

View full text Add to dashboard Cite

The compressible flow past a tabbed cylinder has been studied numerically using large-eddy simulation for a free-stream Mach number M∞=0.75 and a Reynolds number based on the diameter Re=2×10 5 . Because of the passive control of the flow past a tabbed cylinder, the mean drag coefficient of tabbed cylinder is less than that of a corresponding circular cylinder with a drag reduction up to 33%. The fluctuating lift coefficient is greatly suppressed to be nearly zero. Drag reduction due to the shearing process prevails over that due to the compressing process in this flow. Through investigating the mechanisms relevant to passive control of the tab, it is found that suppression of the shear layer instability can lead to a higher-base-pressure distribution, which can reasonably be associated with drag reduction and suppression of the lift fluctuations. The analysis of convective Mach number and self-sustained oscillations phenomenon inside the shear layers indicates that both the compressible effect and high-frequency forcing result in suppression of the shear layer instability of tabbed cylinder. circular cylinder, shock wave, compressible turbulence, large-eddy simulation Citation:Xu C Y, Zhao L Q, Sun J H. Large-eddy simulation of the compressible flow past a tabbed cylinder.

show abstract

Section: Force Behaviorssupporting

confidence: 84%

Section: Force Behaviorsmentioning

confidence: 99%

See 1 more Smart Citation

Large-eddy simulation of the compressible flow past a tabbed cylinder

Zhao

Sun

2012

Chin. Sci. Bull.

View full text Add to dashboard Cite

show abstract

“…Robinson 1991;Jeong & Hussain 1995;Chakraborty, Balachandar & Adrian 2005). Moreover, the Lamb vector acts as a vortex force and its character plays an important role in establishing the nature of the flow (Truesdell 1954;Wu, Lu & Zhuang 2007). The Lamb vector divergence is associated with the momentum transport in the flow field (Wu et al 2007) and appears as an acoustic source term in Lighthill's wave equation (Lighthill 1952;Howe 1975).…”

Section: Introductionmentioning

confidence: 99%

Large-eddy simulation of the compressible flow past a wavy cylinder

Chen

2010

J. Fluid Mech.

116

View full text Add to dashboard Cite

Numerical investigation of the compressible flow past a wavy cylinder was carried out using large-eddy simulation for a free-stream Mach number M∞ = 0.75 and a Reynolds number based on the mean diameter Re = 2 × 105. The flow past a corresponding circular cylinder was also calculated for comparison and validation against experimental data. Various fundamental mechanisms dictating the intricate flow phenomena, including drag reduction and fluctuating force suppression, shock and shocklet elimination, and three-dimensional separation and separated shear-layer instability, have been studied systematically. Because of the passive control of the flow over a wavy cylinder, the mean drag coefficient of the wavy cylinder is less than that of the circular cylinder with a drag reduction up to 26%, and the fluctuating force coefficients are significantly suppressed to be nearly zero. The vortical structures near the base region of the wavy cylinder are much less vigorous than those of the circular cylinder. The three-dimensional shear-layer shed from the wavy cylinder is more stable than that from the circular cylinder. The vortex roll up of the shear layer from the wavy cylinder is delayed to a further downstream location, leading to a higher-base-pressure distribution. The spanwise pressure gradient and the baroclinic effect play an important role in generating an oblique vortical perturbation at the separated shear layer, which may moderate the increase of the fluctuations at the shear layer and reduce the growth rate of the shear layer. The analysis of the convective Mach number indicates that the instability processes in the shear-layer evolution are derived from oblique modes and bi-dimensional instability modes and their competition. The two-layer structures of the shear layer are captured using the instantaneous Lamb vector divergence, and the underlying dynamical processes associated with the drag reduction are clarified. Moreover, some phenomena relevant to the compressible effect, such as shock waves, shocklets and shock/turbulence interaction, are analysed. It is found that the shocks and shocklets which exist in the circular cylinder flow are eliminated for the wavy cylinder flow and the wavy surface provides an effective way of shock control. As the shock/turbulence interaction is avoided, a significant drop of the turbulent fluctuations around the wavy cylinder occurs. The results obtained in this study provide physical insight into the understanding of the mechanisms relevant to the passive control of the compressible flow past a wavy surface.

show abstract

“…The vortex structure around the plate is closely associated with the dynamic characteristics of the plate [10,18] . We further discuss the vortex shedding to understand propulsive performance of the passive flapping plate.…”

Section: Vortex Structures Behind the Flapping Platementioning

confidence: 99%

Propulsive performance of a passively flapping plate in a uniform flow

et al. 2015

View full text Add to dashboard Cite

Propulsive performance of a passively flapping plate in a uniform viscous flow has been studied numerically by means of a multiblock lattice Boltzmann method. The passively flapping plate is modeled by a rigid plate with a torsion spring acting about the pivot at the leading-edge of the plate, which is called a lumped-torsional-flexibility model. When the leading-edge is forced to take a vertical oscillation, the plate pitches passively due to the fluid-plate interaction. Based on our numerical simulations, various fundamental mechanisms dictating the propulsive performance, including the forces on the plate, power consumption, propulsive efficiency and vortical structures, have been studied. It is found that the torsional flexibility of the passively pitching plate can improve the propulsive performance. The results obtained in this study provide some physical insights into the understanding of the propulsive behaviors of swimming and flying animals.

show abstract

Integral force acting on a body due to local flow structures

Cited by 150 publications

References 28 publications

Large-eddy simulation of the compressible flow past a tabbed cylinder

Large-eddy simulation of the compressible flow past a tabbed cylinder

Large-eddy simulation of the compressible flow past a wavy cylinder

Propulsive performance of a passively flapping plate in a uniform flow

Contact Info

Product

Resources

About