Numerical investigation of the separated and reattaching flow over a 5:1 rectangular cylinder in streamwise sinusoidal flow

Abstract Three-dimensional Large-Eddy Simulations (3D LES) are performed to study the separated and reattaching flow over a 5:1 rectangular cylinder in streamwise sinusoidal flow. The ratio of inflow frequency to natural vortex-shedding frequency is varied from 0 to 6 ​at five amplitudes up to 60% of the time-mean velocity. The effect on the two-dimensional (2D) and three-dimensional (3D) characteristics of the separation bubble and surface pressures are reported. The relationship between the time-averaged flow field and the statistics of the chordwise pressure distribution are obtained firstly. The flow-pressure relationships are qualitatively similar in uniform and sinusoidal flows. Then, the amplitude-frequency domain of the sinusoidal flow is divided into three regimes to describe the effects on the mean reattachment length. The simulations capture the interferences between leading-edge vortices and trailing edge vortices for longer separation bubbles. However, the interactions are not observed in shorter separation bubbles due to the diffusions of leading-edge vortices. Finally, the flow three-dimensionality is studied by performing proper orthogonal decomposition (POD) and spanwise correlation analysis on the surface pressures. The oncoming flow oscillations correspond to the most energetic structures dominating the pressure field, which are constant in the spanwise direction. While the local vortical structures mainly influence the 3D features of the flow dynamics.

[1]  K. Lam,et al.  Formation of vortex street and vortex pair from a circular cylinder oscillating in water , 2002 .

[2]  P. Anagnostopoulos,et al.  Viscous oscillatory flow around a circular cylinder at low Keulegan-Carpenter numbers and frequency parameters , 1998 .

[3]  John Sheridan,et al.  Response of base suction and vortex shedding from rectangular prisms to transverse forcing , 2002, Journal of Fluid Mechanics.

[4]  H. Sung,et al.  Control of turbulent separated flow over a backward-facing step by local forcing , 1996 .

[5]  Shaopeng Li,et al.  Large-eddy simulation of the near wake of a 5:1 rectangular cylinder in oscillating flows at Re=670 , 2020 .

[6]  Charles H. K. Williamson,et al.  Sinusoidal flow relative to circular cylinders , 1985, Journal of Fluid Mechanics.

[7]  T. Zhou,et al.  Two-dimensional numerical simulations of flow around a circular cylinder in oscillatory flows at low KC and Reynolds numbers , 2016 .

[8]  Michael Yianneskis,et al.  Bimodal vortex shedding in a perturbed cylinder wake , 2007 .

[9]  M. Braza,et al.  Numerical study and physical analysis of the pressure and velocity fields in the near wake of a circular cylinder , 1986, Journal of Fluid Mechanics.

[10]  Shaopeng Li,et al.  Spectral analysis and coherence of aerodynamic lift on rectangular cylinders in turbulent flow , 2017, Journal of Fluid Mechanics.

[11]  Shaopeng Li,et al.  Experimental investigation on the unsteady lift of an airfoil in a sinusoidal streamwise gust , 2017 .

[12]  F. Ubertini,et al.  Flow field around a 5:1 rectangular cylinder using LES: Influence of inflow turbulence conditions, spanwise domain size and their interaction , 2017 .

[13]  Kyuro Sasaki,et al.  Free-stream turbulence effects on a separation bubble , 1983 .

[14]  W. Rodi.  Comparison of LES and RANS calculations of the flow around bluff bodies , 1997 .

[15]  R. Parker,et al.  Effects of sound on flow separation from blunt flat plates , 1983 .

[16]  Mark C. Thompson,et al.  Augmented forced convection heat transfer in separated flow around a blunt flat plate , 1991 .

[17]  H. Sung,et al.  RELATIONSHIP BETWEEN WALL PRESSURE FLUCTUATIONS AND STREAMWISE VORTICITY IN A TURBULENT BOUNDARY LAYER , 2002, Proceeding of Second Symposium on Turbulence and Shear Flow Phenomena.

[18]  T. Tamura,et al.  Numerical prediction of unsteady pressures on a square cylinder with various corner shapes , 1998 .

[19]  Francesco Ricciardelli,et al.  Benchmark on the Aerodynamics of a Rectangular 5:1 Cylinder: An overview after the first four years of activity , 2014 .

[20]  Oscillatory flow regimes around four cylinders in a square arrangement under small $\mathit{KC}$ and $\mathit{Re}$ conditions , 2015, Journal of Fluid Mechanics.

[21]  Maria Vittoria Salvetti,et al.  Stochastic sensitivity analysis of large-eddy simulation predictions of the flow around a 5:1 rectangular cylinder , 2017 .

[22]  M. Kiya,et al.  Sinusoidal forcing of a turbulent separation bubble , 1997, Journal of Fluid Mechanics.

[23]  Akira Nishi,et al.  Reproduction of wind velocity history in a multiple fan wind tunnel , 2001 .

[24]  Jae Min Hyun,et al.  Flow and mass transfer measurements for a flat plate of finite thickness in pulsating flow , 1998 .

[25]  Parag Deshpande,et al.  Experimental Investigation of Periodic Wind Gust Generated in a Low Speed Wind Tunnel , 2014 .

[26]  George Papadakis,et al.  Large eddy simulation of pulsating flow over a circular cylinder at subcritical Reynolds number , 2007 .

[27]  Aziz Hamdouni,et al.  Numerical simulation of an oscillating cylinder in a cross-flow at low Reynolds number: Forced and free oscillations , 2009 .

[28]  Luca Bruno,et al.  Simulated flow around a rectangular 5:1 cylinder: Spanwise discretisation effects and emerging flow features , 2012 .

[29]  H. Sung,et al.  An experimental study of large-scale vortices over a blunt-faced flat plate in pulsating flow , 2001 .

[30]  C. Liang,et al.  Dynamic response of a turbulent cylinder wake to sinusoidal inflow perturbations across the vortex lock-on range , 2011 .

[31]  R. Hillier,et al.  Pressure fluctuations in a turbulent separated flow , 1985 .

[32]  J. Owen,et al.  Vortex-induced vibration of a 5:1 rectangular cylinder: A comparison of wind tunnel sectional model tests and computational simulations , 2018 .

[33]  A. Cimarelli,et al.  Direct numerical simulation of the flow around a rectangular cylinder at a moderately high Reynolds number , 2018 .

[34]  Günter Schewe,et al.  Reynolds-number-effects in flow around a rectangular cylinder with aspect ratio 1:5 , 2013 .

[35]  Kyuro Sasaki,et al.  Structure of large-scale vortices and unsteady reverse flow in the reattaching zone of a turbulent separation bubble , 1985, Journal of Fluid Mechanics.

[36]  W. H. Melbourne,et al.  Effects of free-stream turbulence on surface pressure fluctuations in a separation bubble , 1997, Journal of Fluid Mechanics.

[37]  Owen M. Griffin,et al.  Review : vortex shedding lock-on and flow control in bluff body wakes , 1991 .

[38]  Tomomi Yagi,et al.  Study on the unsteady pressure field around the oscillatory B/D=4 rectangular section using proper orthogonal decomposition analysis , 2006 .

[39]  N. J. Cherry,et al.  The effects of stream turbulence on separation bubbles , 1981 .

[40]  D. Favier,et al.  Vortex shedding and lock-on of a circular cylinder in oscillatory flow , 1986, Journal of Fluid Mechanics.

[41]  H. H. Fernholz,et al.  An experimental investigation of a turbulent shear flow with separation, reverse flow, and reattachment , 1986, Journal of Fluid Mechanics.

[42]  B. P. Leonard,et al.  The ULTIMATE conservative difference scheme applied to unsteady one-dimensional advection , 1991 .

[43]  Hamid Naderan,et al.  A numerical study of flow past a cylinder with cross flow and inline oscillation , 2006 .

[44]  Michael Yianneskis,et al.  The effect of flow perturbations on the near wake characteristics of a circular cylinder , 2003 .

[45]  Owen M. Griffin,et al.  Vortex shedding from a cylinder vibrating in line with an incident uniform flow , 1976, Journal of Fluid Mechanics.

[46]  Shaopeng Li,et al.  Numerical and experimental studies on the aerodynamics of a 5:1 rectangular cylinder at angles of attack , 2020 .

[47]  Lin Zhao,et al.  Investigations of aerodynamic effects on streamlined box girder using two-dimensional actively-controlled oncoming flow , 2013 .

[48]  Emanuele Zappa,et al.  Complex aerodynamic admittance function role in buffeting response of a bridge deck , 2001 .

[49]  L. Sigurdson.  The structure and control of a turbulent reattaching flow , 1995, Journal of Fluid Mechanics.

[50]  Gianni Bartoli,et al.  The effects of free-stream turbulence and angle of attack on the aerodynamics of a cylinder with rectangular 5:1 cross section , 2017 .

[51]  A. Nishi,et al.  Active control of turbulence for an atmospheric boundary layer model in a wind tunnel , 1999 .

[52]  S. Cao,et al.  Numerical study of flow over a circular cylinder in oscillatory flows with zero-mean and non-zero-mean velocities , 2015 .

[53]  O. Griffin,et al.  Vortex Shedding and Lock-On in a Perturbed Flow , 1993 .

[54]  Shaopeng Li,et al.  The lift on an aerofoil in grid-generated turbulence , 2015, Journal of Fluid Mechanics.

[55]  F. H. Barnes,et al.  A comparison of the structure of the wake behind a circular cylinder in a steady flow with that in a perturbed flow , 1987 .

[56]  F. H. Barnes,et al.  The effect of a perturbation on the flow over a bluff cylinder , 1986 .

[57]  F. Roos,et al.  Evolving three-dimensionality in a reattaching two-dimensional turbulent shear layer , 1987 .

[58]  Xiaotao Zheng,et al.  Effect on the flow and heat transfer characteristics for sinusoidal pulsating laminar flow in a heated square cylinder , 2014 .

[59]  L. Bruno,et al.  3D flow around a rectangular cylinder: A computational study , 2010 .

[60]  N. J. Cherry,et al.  Unsteady measurements in a separated and reattaching flow , 1984, Journal of Fluid Mechanics.

[61]  Two-dimensional and three-dimensional simulations of oscillatory flow around a circular cylinder , 2015 .

[62]  In-Won Lee,et al.  Multiple-arrayed pressure measurement for investigation of the unsteady flow structure of a reattaching shear layer , 2002, Journal of Fluid Mechanics.

[63]  Yuji Matsuda,et al.  Turbulence control in multiple-fan wind tunnels , 1997 .

[64]  Peter W. Bearman,et al.  A visual study of the flow around an oscillating circular cylinder at low Keulegan–Carpenter numbers and low Stokes numbers , 1990, Journal of Fluid Mechanics.

[65]  Y. Tanida,et al.  Stability of a circular cylinder oscillating in uniform flow or in a wake , 1973, Journal of Fluid Mechanics.

[66]  Yukio Tamura,et al.  Proper orthogonal decomposition and reconstruction of multi-channel roof pressure , 1995 .