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Hydrodynamic interactions of water waves with a group of independently oscillating truncated circular cylinders 被引量:1
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作者 Xiaohui Zeng Min Shi Shanlin Huang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2016年第5期773-791,共19页
In this study, we examine the water wave radiation by arrays of truncated circular cylinders. Each cylinder can oscillate independently in any rigid oscillation mode with a prescribed amplitude, including translationa... In this study, we examine the water wave radiation by arrays of truncated circular cylinders. Each cylinder can oscillate independently in any rigid oscillation mode with a prescribed amplitude, including translational and rotational modes such as surge, sway, heave, pitch, roll, and their combinations. Based on the eigenfunction expansion and Graf's addition theorem for Bessel functions, we developed an analytical method that includes the effects of evanescent modes in order to analyze such arrays of cylinders. To investigate the effects of several influential factors on convergence,our objective is to dramatically reduce the number of tests required and determine the influencing relationships between truncation number and convergence behavior for different factor combinations. We use the orthogonal test method to fulfill the objective. Lastly, we present our results regarding the effects of evanescent modes on hydrodynamic coefficients. 展开更多
关键词 Radiation Water wave Arrays of truncated circular cylinders oscillating independently Translational oscillation Rotational oscillation
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Resonance in flow past oscillating cylinder under subcritical conditions 被引量:1
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作者 Renjie JIANG Pengjun ZHENG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2017年第3期363-378,共16页
Flow around an oscillating cylinder in a subcritical region are numerically studied with a lattice Boltzmann method(LBM). The effects of the Reynolds number,oscillation amplitude and frequency on the vortex wake modes... Flow around an oscillating cylinder in a subcritical region are numerically studied with a lattice Boltzmann method(LBM). The effects of the Reynolds number,oscillation amplitude and frequency on the vortex wake modes and hydrodynamics forces on the cylinder surface are systematically investigated. Special attention is paid to the phenomenon of resonance induced by the cylinder oscillation. The results demonstrate that vortex shedding can be excited extensively under subcritical conditions, and the response region of vibration frequency broadens with increasing Reynolds number and oscillation amplitude. Two distinct types of vortex shedding regimes are observed. The first type of vortex shedding regime(VSR I) is excited at low frequencies close to the intrinsic frequency of flow, and the second type of vortex shedding regime(VSR II)occurs at high frequencies with the Reynolds number close to the critical value. In the VSR I, a pair of alternately rotating vortices are shed in the wake per oscillation cycle,and lock-in/synchronization occurs, while in the VSR II, two alternately rotating vortices are shed for several oscillation cycles, and the vortex shedding frequency is close to that of a stationary cylinder under the critical condition. The excitation mechanisms of the two types of vortex shedding modes are analyzed separately. 展开更多
关键词 oscillating cylinder subcritical region resonance phenomenon lattice Boltzmann method(LBM)
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AN EXPERIMENTAL STUDY OF FLUCTUATING LIFT ON A SQUARE-SECTION CYLINDER OSCILLATING TRANSVERSELY IN A UNIFORM STREAM
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作者 Huhe-Aode Meng Xiangyang (Institute of Mechanics,Academia Sinica) 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 1991年第2期104-110,共7页
Experiments on a square section cylinder fixed and forced to oscillate transversely in a uni- form stream were conducted in a water tank.The Reynolds numberof the experiments is in the range of 3·10~3 tO 10~4,the... Experiments on a square section cylinder fixed and forced to oscillate transversely in a uni- form stream were conducted in a water tank.The Reynolds numberof the experiments is in the range of 3·10~3 tO 10~4,the amplitude to side length ratio A/D is up to 0.7 and the range of reduced velocity is 4.5<Vr<12.This study aims at investigating the lock-in phenomenon,the fluctuating lift and the phase shift between fluctuating lift and displacement of the oscillating cylinder.The problems on the aeroelastic insta. bility relating to present experimental results have been discussed.The flow visualization clearly shows that there are drastic changes of vortex-shedding from cylinder at the resonance point and the upper end of the lock-in range.The results of the flow visualization give better understanding of the physical mechanism of the phase shift. 展开更多
关键词 oscillating cylinder fluctuating force vortex-shedding NEAR-WAKE LOCK-IN
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Experimental Investigation of Lift Forces on Horizontal Cylinder near Bottom in Oscillating Flow
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作者 桂劲松 刘红 +1 位作者 周岩辉 康海贵 《Marine Science Bulletin》 CAS 2002年第2期1-7,共7页
The lift forces on horizontal cylinder near bottom is experimentally investigated at Reynolds numbers (Re) in the range of 2 500~10 000 and Keulegan^Carpenter numbers (Kc) in the interval of 5~20, and gap ratio (e/D) ... The lift forces on horizontal cylinder near bottom is experimentally investigated at Reynolds numbers (Re) in the range of 2 500~10 000 and Keulegan^Carpenter numbers (Kc) in the interval of 5~20, and gap ratio (e/D) is from 0.2 to 1.0. Lift force coefficient (CL) and the deviation value of lift force (a0) are analyzed by using the Fourier analysis method. It is found that both CL & a0 are the functions of the Kc number. 展开更多
关键词 oscillating flow horizontal cylinder LIFT forces FOURIER analysis
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Experimental Study on Flow past A Rotationally Oscillating Cylinder
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作者 GAO Yang-yang YIN Chang-shan +2 位作者 YANG Kang ZHAO Xi-zeng TAN Soon Keat 《China Ocean Engineering》 SCIE EI CSCD 2017年第4期495-503,共9页
A series of experiments was carried out to study the flow behaviour behind a rotationally oscillating cylinder at a low Reynolds number (Re=300) placed in a recirculation water channel. A stepper motor was used to r... A series of experiments was carried out to study the flow behaviour behind a rotationally oscillating cylinder at a low Reynolds number (Re=300) placed in a recirculation water channel. A stepper motor was used to rotate the cylinder clockwise- and- counterclockwise about its longitudinal axis at selected frequencies. The particle image velocimetry (PIV) technique was used to capture the flow field behind a rotationally oscillating cylinder. Instantaneous and time-averaged flow fields such as the vorticity contours, streamline topologies and velocity distributions were analyzed. The effects of four rotation angle and frequency ratios Fr (Fr=fn/fv, the ratio of the forcing frequency fn to the natural vortex shedding frequency fv) on the wake in the lee of a rotationally oscillating cylinder were also examined. The significant wake modification was observed when the cylinder undergoes clockwise-and-counterclockwise motion with amplitude of π, especially in the range of 0.6≤Fr≤1.0. 展开更多
关键词 rotational oscillation cylinder PIV frequency ratio wake flow pattern time-averaged flow field
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Modeling and fuzzy adaptive proportion-integration-differentiation control of X-Y position servo system actuated by oscillating pneumatic cylinder
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作者 袁德虎 Zhang Ziqun Meng Guoxiang 《High Technology Letters》 EI CAS 2010年第4期337-344,共8页
The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinear control system. Its mathematical model is established, and nonlinear factors are analyzed. Due to the existence o... The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinear control system. Its mathematical model is established, and nonlinear factors are analyzed. Due to the existence of deadlock zone and the small damp of the pneumatic oscillating cylinder, it is likely to result in overshoot, and there is also certain steady-state error, so online modifying of proportion-integration-differentiation (PID) parameters is needed so as to achieve better control performance. Meanwhile considering the stability demand for long-term run, a fuzzy adaptive PID controller is designed. The result of hardware-inloop (HIL) test and real-time control experiment shows that the adaptive PID controller has desirable serfadaptability and robustness to external disturbance and to change of system parameters, and its control per- fonnance is better than that of traditional PID controllers. 展开更多
关键词 fuzzy adaptive control servo system actuated by oscillating cylinder hardware-in-loop (HIL) trajectory tracking
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Study on Periodic MHD Flow with Temperature Dependent Viscosity and Thermal Conductivity past an Isothermal Oscillating Cylinder
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作者 Rubel Ahmed Reaz Uddin +2 位作者 B. M. Jewel Rana Rafrafin Selim Sarder Firoz Ahmmed 《World Journal of Mechanics》 2016年第11期419-441,共22页
Temperature dependent viscosity and thermal conducting heat and mass transfer flow with chemical reaction and periodic magnetic field past an isothermal oscillating cylinder have been considered. The partial dimension... Temperature dependent viscosity and thermal conducting heat and mass transfer flow with chemical reaction and periodic magnetic field past an isothermal oscillating cylinder have been considered. The partial dimensionless equations governing the flow have been solved numerically by applying explicit finite difference method with the help Compaq visual 6.6a. The obtained outcome of this inquisition has been discussed for different values of well-known flow parameters with different time steps and oscillation angle. The effect of chemical reaction and periodic MHD parameters on the velocity field, temperature field and concentration field, skin-friction, Nusselt number and Sherwood number have been studied and results are presented by graphically. The novelty of the present problem is to study the streamlines by taking into account periodic magnetic field. 展开更多
关键词 Chemical Reaction Periodic MHD oscillating cylinder Variable Viscosity Thermal Conductivity
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Shear flow induced vibrations of long slender cylinders with a wake oscillator model 被引量:4
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作者 Fei Ge Wei Lu Lei Wang You-Shi Hong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第3期330-338,共9页
A time domain model is presented to study the vibrations of long slender cylinders placed in shear flow. Long slender cylinders such as risers and tension legs are widely used in the field of ocean engineering. They a... A time domain model is presented to study the vibrations of long slender cylinders placed in shear flow. Long slender cylinders such as risers and tension legs are widely used in the field of ocean engineering. They are subjected to vortex-induced vibrations(VIV) when placed within a transverse incident flow. A three dimensional model coupled with wake oscillators is formulated to describe the response of the slender cylinder in cross-flow and in-line directions. The wake oscillators are distributed along the cylinder and the vortex-shedding frequency is derived from the local current velocity. A non-linear fiuid force model is accounted for the coupled effect between cross-flow and in-line vibrations. The comparisons with the published experimental data show that the dynamic features of VIV of long slender cylinder placed in shear flow can be obtained by the proposed model,such as the spanwise average displacement,vibration frequency,dominant mode and the combination of standing and traveling waves. The simulation in a uniform flow is also conducted and the result is compared with the case of nonuniform flow. It is concluded that the flow shear characteristic has significantly changed the cylinder vibration behavior. 展开更多
关键词 Vortex-induced vibration Vortex-induced wave Shear flow Wake oscillator Long slender cylinder
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A Novel Wake Oscillator Model for Vortex-Induced Vibrations Prediction of A Cylinder Considering the Influence of Reynolds Number 被引量:2
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作者 GAO Xi-feng XIE Wu-de +2 位作者 XU Wan-hai BAI Yu-chuan ZHU Hai-tao 《China Ocean Engineering》 SCIE EI CSCD 2018年第2期132-143,共12页
It is well known that the Reynolds number has a significant effect on the vortex-induced vibrations(VIV) of cylinders. In this paper, a novel in-line(IL) and cross-flow(CF) coupling VIV prediction model for circular c... It is well known that the Reynolds number has a significant effect on the vortex-induced vibrations(VIV) of cylinders. In this paper, a novel in-line(IL) and cross-flow(CF) coupling VIV prediction model for circular cylinders has been proposed, in which the influence of the Reynolds number was comprehensively considered. The Strouhal number linked with the vortex shedding frequency was calculated through a function of the Reynolds number. The coefficient of the mean drag force was fitted as a new piecewise function of the Reynolds number, and its amplification resulted from the CF VIV was also taken into account. The oscillating drag and lift forces were modelled with classical van der Pol wake oscillators and their empirical parameters were determined based on the lock-in boundaries and the peak-amplitude formulas. A new peak-amplitude formula for the IL VIV was developed under the resonance condition with respect to the mass-damping ratio and the Reynolds number. When compared with the results from the experiments and some other prediction models, the present model could give good estimations on the vibration amplitudes and frequencies of the VIV both for elastically-mounted rigid and long flexible cylinders. The present model considering the influence of the Reynolds number could generally provide better results than that neglecting the effect of the Reynolds number. 展开更多
关键词 vortex-induced vibrations Reynolds number wake oscillator model cylinder
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Hydrodynamics of the Semi-Immersed Cylinder by Forced Oscillation Model Testing 被引量:1
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作者 SONG Chun-hui FU Shi-xiao +3 位作者 TANG Xiao-ying HU Ke MA Lei-xin REN Tong-xin 《China Ocean Engineering》 SCIE EI CSCD 2018年第1期110-116,共7页
In this paper, the hydrodynamic coefficients of a horizontal semi-immersed cylinder in steady current and oscillatory flow combining with constant current are obtained via forced oscillation experiments in a towing ta... In this paper, the hydrodynamic coefficients of a horizontal semi-immersed cylinder in steady current and oscillatory flow combining with constant current are obtained via forced oscillation experiments in a towing tank. Three nondimensional parameters(Re, KC and Fr) are introduced to investigate their effects on the hydrodynamic coefficients.The experimental results show that overtopping is evident and dominates when the Reynolds number exceeds 5×105 in the experiment. Under steady current condition, overtopping increases the drag coefficient significantly at high Reynolds numbers. Under oscillatory flow with constant current condition, the added mass coefficient can even reach a maximum value about 3.5 due to overtopping while the influence of overtopping on the drag coefficient is minor. 展开更多
关键词 semi-immersed cylinder hydrodynamic coefficient forced oscillation experiment OVERTOPPING
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Rotational Oscillation Effect on Flow Characteristics of a Circular Cylinder at Low Reynolds Number
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作者 Alice Rosa da Silva Aristeu da Silveira-Neto Antonio Marcos Goncalves de Lima 《World Journal of Mechanics》 2015年第10期195-209,共15页
Two dimensional numerical simulations of flow around a rotationally oscillating circular cylinder were performed at Re = 1000. A wide range of forcing frequencies, fr, and three values of oscillation amplitudes, A, ar... Two dimensional numerical simulations of flow around a rotationally oscillating circular cylinder were performed at Re = 1000. A wide range of forcing frequencies, fr, and three values of oscillation amplitudes, A, are considered. Different vortex shedding modes are observed for a fixed A at several values of fr, as well as for a fixed fr at different values of A. The 2C mode of vortex shedding was obtained in the present study. It is important to point out that this mode has not been observed by other investigators for rotationally oscillating case. Also, it is verified that this mechanism has great influence on the drag coefficient for high frequency values. Furthermore, the lift and pressure coefficients and the power spectra density are also analyzed. 展开更多
关键词 Rotationally oscillating cylinder Vortex Shedding Modes Drag Coefficient
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Vortex-Induced Vibrations of A Long Flexible Cylinder in Linear and Exponential Shear Flows 被引量:4
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作者 GAO Yun YANG Bin +2 位作者 ZOU Li ZONG Zhi ZHANG Zhuang-zhuang 《China Ocean Engineering》 SCIE EI CSCD 2019年第1期44-56,共13页
A numerical study based on a wake oscillator model was conducted to determine the response performance of vortex-induced vibration(VIV) on a long flexible cylinder with pinned-pinned boundary conditions subjected to l... A numerical study based on a wake oscillator model was conducted to determine the response performance of vortex-induced vibration(VIV) on a long flexible cylinder with pinned-pinned boundary conditions subjected to linear and exponential shear flows. The coupling equations of a structural vibration model and wake oscillator model were solved using a standard central finite difference method of the second order. The VIV response characteristics including the structural displacement, structural frequency, structural wavenumber, standing wave behavior,travelling wave behavior, structural velocity, lift force coefficient and transferred energy from the fluid to the structure with different flow profiles were compared. The numerical results show that the VIV displacement is a combination of standing waves and travelling waves. For linear shear flow, standing waves and travelling waves dominate the VIV response within the low-velocity and high-velocity zones, respectively. The negative values of the transferred energy only occur within the low-velocity zone. However, for exponential shear flow, travelling waves dominate the VIV response and the negative energy occurs along the entire length of the cylinder. 展开更多
关键词 vortex-induced vibration LONG FLEXIBLE cylinder WAKE oscillator model EXPONENTIAL shear flow TRANSFERRED energy
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Combined Action of Uniform Flow and Oscillating Flow Around Marine Riser at Low Keulegan-Carpenter Number 被引量:4
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作者 DENG Yue HUANG Weiping ZHAO Jingli 《Journal of Ocean University of China》 SCIE CAS 2014年第3期390-396,共7页
With the increase of petroleum and gas production in deep ocean, marine risers of circular cylinder shape are widely used in the offshore oil and gas platform. In order to research the hydrodynamic performance of mari... With the increase of petroleum and gas production in deep ocean, marine risers of circular cylinder shape are widely used in the offshore oil and gas platform. In order to research the hydrodynamic performance of marine risers, the dynamic mesh technique and User-Defined Function(UDF) are used to simulate the circular cylinder motion. The motion of a transversely oscillating circular cylinder in combination of uniform flow and oscillating flow is simulated. The uniform flow and oscillating flow both are in x direction. SIMPLE algorithm is used to solve the Navier-Stokes equations. The User-Defined Function is used to control the cylinder transverse vibration and the inlet flow. The lift and drag coefficient changing with time and the map of vorticity isolines at different phase angle are obtained. Force time histories are shown for uniform flow at Reynolds number(Re) of 200 and for the combination of uniform and oscillating flows. With the increase of amplitude of oscillating flow in combined flow, the change of lift amplitude is not sensitive to the the change of cylinder oscillating frequency. Lift amplitude increases with the increase of oscillating flow amplitude in the combined flow, but there is no definite periodicity of the lift coefficient. The drag and inertia force coefficients change when the maximum velocity of the oscillating flow increases in the combined flow. The vortex shedding near the circular cylinder shows different characteristics. 展开更多
关键词 transversely oscillating cylinder circular cylinder marine riser uniform flow oscillating flow vorticity isolines
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Prediction of Streamwise Flow-Induced Vibration of A Circular Cylinder in the First Instability Range 被引量:2
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作者 徐万海 余建星 +2 位作者 杜杰 成安康 康昊 《China Ocean Engineering》 SCIE EI 2012年第4期555-564,共10页
The streamwise flow-induced vibration of a circular cylinder with symmetric vortex shedding in the first instability range is investigated, and a wake oscillator model for the dynamic response prediction is proposed. ... The streamwise flow-induced vibration of a circular cylinder with symmetric vortex shedding in the first instability range is investigated, and a wake oscillator model for the dynamic response prediction is proposed. An approach is applied to calibrate the empirical parameters in the present model; the numerical and experimental results are compared to validate the proposed model. It can be found that the present prediction model is accurate and sufficiently simple to be easily applied in practice. 展开更多
关键词 streamwise flow-induced vibrations circular cylinder wake oscillator model first instability range
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A Forced System of Two Cylinders with Various Spacings 被引量:2
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作者 邹建锋 任安禄 邓见 《海洋工程:英文版》 2004年第3期391-402,共12页
The spectrum characteristics and wake structures for a circular cylinder oscillating in a wake are investigated by use of the currently modified virtual boundary method. A forced system of two cylinders with a small s... The spectrum characteristics and wake structures for a circular cylinder oscillating in a wake are investigated by use of the currently modified virtual boundary method. A forced system of two cylinders with a small spacing (the downstream one is made to oscillate in the transverse direction) is studied and interesting flow characteristics are observed. A vortex switch and the change of vortex modes (between 2S mode and 2P mode) are observed in the “lock in' region. Vortex bands are formed and lost with the increasing excitation frequency. Information concerning saddle points in the flow field is obtained for different excitation frequencies. For a forced system of two cylinders with a large spacing, the upstream cylinder sheds vortexes because there is no downstream cylinder oscillating in the wake. No distinct “lock in' response is found for the downstream cylinder. 展开更多
关键词 virtual boundary method oscillating cylinder wake structure SPECTRA
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Flow Dynamics around Two Side by Side Circular Cylinders with Alternating Movements
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作者 Alice Rosa da Silva 《World Journal of Mechanics》 2023年第1期1-19,共19页
The flow dynamics is analyzed through two-dimensional numerical simulations around two circular cylinders arranged side by side, with 4 combinations of alternating motions. All simulations are performed for Re = 1000,... The flow dynamics is analyzed through two-dimensional numerical simulations around two circular cylinders arranged side by side, with 4 combinations of alternating motions. All simulations are performed for Re = 1000, amplitude of oscillation (A) equal to 3, frequency ratio (f<sub>r</sub>) of 0.5, specific rotation (α) equal to 0.5 and different values of spacing ratio (L/D). It is verified that the combination of the type of movement, together with the position of one cylinder in relation to the other, exerts significant influence on the flow dynamics, as well as on the pressure distribution around the cylinder surface and on the average values of the fluid dynamics coefficients. The smallest value of the average pressure coefficient (C<sub>p</sub> = -3.3), is obtained for the oscillating cylinder when placed side by side with the clockwise rotation cylinder, case 3 and L/D = 1.5. On the other hand, the lowest mean drag coefficient (C<sub>d</sub> = 1.0788), is obtained for the cylinder with counterclockwise rotation, located in the lower position in relation to oscillating cylinder in the upper position, with spacing between them of 1.5. Furthermore, it is observed that the rotation movement is more effective in reducing drag than the rotation-oscillation movement, for the studied frequency ratio. 展开更多
关键词 ROTATION Rotation-oscillation Flow Dynamic Circular cylinder
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NUMERICAL SIMULATION OF AN OSCILLATING FLOW PAST A CIRCULAR CYLINDER IN THE VICINITY OF A PLANE WALL 被引量:7
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作者 SHAH Syed Bilal Hussain 《Journal of Hydrodynamics》 SCIE EI CSCD 2008年第5期547-552,共6页
Oscillating flow around a circular cylinder in the vicinity of a plane wall was investigated by solving the two-dimensional incompressible Navier-Stokes equations with a finite element Galarkin residual method. The ef... Oscillating flow around a circular cylinder in the vicinity of a plane wall was investigated by solving the two-dimensional incompressible Navier-Stokes equations with a finite element Galarkin residual method. The effect of the gap G/D between the cylinder surface and the wall on the flow behavior was studied. For the case of G/D 〈 0.25, the periodicity in the flow is attributed to both the outer shear layer instability and the oscillating frequency. As G/D 〉 0.25, vortex shedding occurs and the periodicity in the flow is mainly due to the competition of the oscillating frcqucncy and the vortex shedding frequency from an isolated stationary cylinder. 展开更多
关键词 finite element method vortex shedding oscillating flow circular cylinder
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Numerical simulation of viscous flow past an oscillating square cylinder using a CIP-based model 被引量:4
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作者 付英男 赵西增 +3 位作者 曹飞凤 张大可 程都 李莉 《Journal of Hydrodynamics》 SCIE EI CSCD 2017年第1期96-108,共13页
The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University (CIP-ZJU). The... The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University (CIP-ZJU). The model is established in the Cartesian coordinate system using the CIP method to discretise the Navier-Stokes equations. The fluid-structure interaction is treated as a multiphase flow of the liquid and solid phases to be solved simultaneously. An immersed boundary method is used to deal with the boundary of the solid body. The CFD model is first applied to the computation of the flow past a fixed square cylinder for its validation. Computations are then performed for the flow past a square cylinder oscillating in the streamwise direction. Considerable attention is paid to the symmetric and anti-symmetric modes of the vortex shedding in the oscillating square cylinder wake. Various oscillation amplitudes and frequencies are simulated and their effects on the vortex shedding modes are analyzed via Lissajous patterns of the unsteady lift coefficient. The relationship among the lift coefficient, the drag coefficient and the lock-on range is also investigated quantitatively. 展开更多
关键词 Flow past cylinder oscillating square cylinder LOCK-ON CIP method immersed boundary method
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VANISHING OF THREE-DIMENSIONALITY IN THE WAKE BEHIND A ROTATIONALLY OSCILLATING CIRCULAR CYLINDER 被引量:5
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作者 DENG Jian SHAO Xue-ming REN An-lu 《Journal of Hydrodynamics》 SCIE EI CSCD 2007年第6期751-755,共5页
The flow behind a three-dimensional rotationally oscillating circular cylinder was studied by a numerical method. The computations were performed at a Reynolds number of 260, which is at a level that the flow wake has... The flow behind a three-dimensional rotationally oscillating circular cylinder was studied by a numerical method. The computations were performed at a Reynolds number of 260, which is at a level that the flow wake has developed into a three-dimensional state called Mode-B. The purpose of this paper is to examine the influence of various rotational amplitudes (0.1-0.7) on the wake instability of the flow, while the oscillation frequency is fixed to the value of that measured in the wake of a stationary cylinder. The results show that the rotation with sufficiently high amplitude brings the flow back to its nominal two-dimensional state. Moreover, it is found that the value of the time-averaged drag and the RMS value of the lift are larger than those of a stationary circular cylinder. 展开更多
关键词 rotationally oscillating circular cylinder wake instability oscillation frequency
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The effects of attached flexible tail length on the flow structure of an oscillating cylinder 被引量:3
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作者 HU Ye WANG JinJun 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第2期340-352,共13页
Particle Imaging Velocimetry (PIV) is utilized to investigate the flow structures of an oscillating cylinder attached to a flexible tail. At the same oscillation frequency and amplitude, the mean streamwise velocity... Particle Imaging Velocimetry (PIV) is utilized to investigate the flow structures of an oscillating cylinder attached to a flexible tail. At the same oscillation frequency and amplitude, the mean streamwise velocity along the wake central-line and the mean vertical velocity around the trailing edge of the flexible tail can be greatly increased with the tail length. Meanwhile, the longer the flexible tail is, the larger its deformation is. In order to study the influence of flexible tail length on the wake pattern of the experimental model, the relationships between the swirling strength Aci of vortex structure near the tail end and the velocity of tail trailing edge have been revealed. Moreover, the convection tracks and the Aci of vortex cores for different flexible tails are discussed. 展开更多
关键词 oscillating cylinder flexible tail tail deformation vortex structures mean flow characteristics
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