Theoretical Calculations of the Flow Around a Rotating Circular Cylinder Placed in a Uniform Flow

1988 ◽  
Vol 110 (1) ◽  
pp. 96-98 ◽  
Author(s):  
Taha K. Aldoss ◽  
Awad Mansour
Keyword(s):  
Circular Cylinder ◽  
Velocity Distribution ◽  
Theoretical Calculations ◽  
Rotating Cylinder ◽  
Uniform Flow ◽  
Front Part ◽  
Rotating Circular Cylinder ◽  
Torque Coefficient ◽  
Lift And Drag ◽  
Linear Pressure Distribution

The rotation of a circular cylinder placed in a uniform flow is assumed to add a circulation to the flow around the cylinder proportional to the product of the angular velocity of the cylinder and the front area between upper and lower separation points. Adding the velocity due to this induced circulation to the base velocity distribution of the non-rotating cylinder the new velocity distribution on the rotating cylinder is formed. Thwaites’ method is then used to calculate the laminar boundary layer on the upper and on the lower sides of the cylinder. The stagnation point, and the upper and lower separation points are also calculated at different values of rotational speed. The calculated lift and drag coefficients using a linear pressure distribution on the wake part of the cylinder with the calculated pressure dstribution on the front part between the two separation points show the same trend as the measured values. The torque coefficient is also calculated to estimate the necessary power required to rotate the cylinder to produce the needed lift.

Flow Simulation Around a Rotating Circular Cylinder With Surface Roughness by the Vortex Method

2003 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
Yuko Matsubara
Keyword(s):  
Surface Roughness ◽  
Circular Cylinder ◽  
Flow Simulation ◽  
Vortex Method ◽  
Uniform Flow ◽  
Speed Ratio ◽  
Rotating Speed ◽  
Rotating Circular Cylinder ◽  
Two Dimensional Flow ◽  
Good Agreement

The two-dimensional flow around a rotating circular cylinder with surface roughness in a steady uniform flow is investigated using a vortex method. The Reynolds number is 9500, while the rotating speed ratios of the peripheral velocity to the uniform velocity is 0–1.0. The surface roughness is distributed around the circular cylinder and its strength is 0.5% of the diameter. The viscous diffusion effects and the no-slip condition are considered. Before the calculation for a rotating circular cylinder with the surface roughness, the flow simulation for a circular cylinder in the steady uniform flow was conducted to confirm the present method. The development of the twin vortices and the velocity profiles behind the circular cylinder at the beginning of the calculation are compared with the previous experimental results. It is found that the calculated results are in good agreement with the experiments. The development of the vortices, the drag and the lift coefficients are computed by changing the rotating speed ratio for the circular cylinder both with the surface roughness and without it. The influence of the surface roughness and the rotating speed ratio on the vortex development, the drag and the lift coefficients are examined.

scholarly journals Experimental investigation of flow-induced vibration of a rotating circular cylinder

2017 ◽  
Vol 829 ◽  
pp. 486-511 ◽  
Author(s):  
K. W. L. Wong ◽  
J. Zhao ◽  
D. Lo Jacono ◽  
M. C. Thompson ◽  
J. Sheridan
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Rotation Rate ◽  
Rotating Cylinder ◽  
Flow Induced Vibration ◽  
Amplitude Response ◽  
Number Range ◽  
Rotating Circular Cylinder ◽  
Numerical Predictions

While flow-induced vibration of bluff bodies has been extensively studied over the last half-century, only limited attention has been given to flow-induced vibration of elastically mounted rotating cylinders. Since recent low-Reynolds-number numerical work suggests that rotation can enhance or suppress the natural oscillatory response, the former could find applications in energy harvesting and the latter in vibration control. The present experimental investigation characterises the dynamic response and wake structure of a rotating circular cylinder undergoing vortex-induced vibration at a low mass ratio ($m^{\ast }=5.78$) over the reduced velocity range leading to strong oscillations. The experiments were conducted in a free-surface water channel with the cylinder vertically mounted and attached to a motor that provided constant rotation. Springs and an air-bearing system allow the cylinder to undertake low-damped transverse oscillations. Under cylinder rotation, the normalised frequency response was found to be comparable to that of a freely vibrating non-rotating cylinder. At reduced velocities consistent with the upper branch of a non-rotating transversely oscillating cylinder, the maximum oscillation amplitude increased with non-dimensional rotation rate up to $\unicode[STIX]{x1D6FC}\approx 2$. Beyond this, there was a sharp decrease in amplitude. Notably, this critical value corresponds approximately to the rotation rate at which vortex shedding ceases for a non-oscillating rotating cylinder. Remarkably, at $\unicode[STIX]{x1D6FC}=2$ there was approximately an 80 % increase in the peak amplitude response compared to that of a non-rotating cylinder. The observed amplitude response measured over the Reynolds-number range of ($1100\lesssim Re\lesssim 6300$) is significantly different from numerical predictions and other experimental results recorded at significantly lower Reynolds numbers.

Turbulent fluid-structure interaction of water-entry/exit of a rotating circular cylinder using SPH method

2015 ◽  
Vol 26 (08) ◽  
pp. 1550088 ◽  
Author(s):  
Jafar Ghazanfarian ◽  
Roozbeh Saghatchi ◽  
Mofid Gorji-Bandpy
Keyword(s):  
Circular Cylinder ◽  
Water Entry ◽  
Numerical Code ◽  
Navier Stokes ◽  
Inertia Force ◽  
Entry And Exit ◽  
Sph Method ◽  
Drag Forces ◽  
Rotating Circular Cylinder ◽  
Lift And Drag

This paper studies the two-dimensional (2D) water-entry and exit of a rotating circular cylinder using the Sub-Particle Scale (SPS) turbulence model of a Lagrangian particle-based Smoothed-Particle Hydrodynamics (SPH) method. The full Navier–Stokes (NS) equations along with the continuity have been solved as the governing equations of the problem. The accuracy of the numerical code is verified using the case of water-entry and exit of a nonrotating circular cylinder. The numerical simulations of water-entry and exit of the rotating circular cylinder are performed at Froude numbers of 2, 5, 8, and specific gravities of 0.25, 0.5, 0.75, 1, 1.75, rotating at the dimensionless rates of 0, 0.25, 0.5, 0.75. The effect of governing parameters and vortex shedding behind the cylinder on the trajectory curves, velocity components in the flow field, and the deformation of free surface for both cases have been investigated in detail. It is seen that the rotation has a great effect on the curvature of the trajectory path and velocity components in water-entry and exit cases due to the interaction of imposed lift and drag forces with the inertia force.

Flow Around a Suddenly Start Rotating Circular Cylinder and Introduce a New Paradox

2007 ◽  
Author(s):  
Baku M. Nagai ◽  
Muhammed Sohel Rana ◽  
Kazumasa Ameku ◽  
Junji Chinen
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Velocity Distribution ◽  
Analytic Solution ◽  
Stokes Equations ◽  
Experimental Results ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Rotating Circular Cylinder ◽  
Theoretical Results

There have been many misunderstanding about the flow around vortices for example a stationary and/or moving vortex pair. The authors have pointed out that no fluid dynamics textbooks have accepted the existence of stationary or arbitral speed moving vortices. About the vortex flow, recently the authors have found a new analytic solution of the Navier-Stokes equations for two-dimensional flow around a suddenly start rotating circular cylinder. This analytic solution explains the velocity distribution, vorticity distribution with change in time, and boundary layer thickness close to a vortex filament because of the action of viscosity. The resulting solutions are involved simple exponential function. Authors present a new construction for the solution of the Navier-Stokes equations for suddenly start rotating circular cylinder. New solution is based on the concept of the similarity solution approach using similarity variable, dimensional analysis, initial, & boundary conditions. A brief theoretical discussion is presented about the suddenly start rotating circular cylinder. The second part of the paper deals with the analytic solution being compared with experimental results in various Reynolds number. A typical measurement is that of relaxation of rotational velocities when the cylinder is subjected only to the viscous resistance. To measure the velocity distribution of the flow the experiments were made with the help of tracer particle (aluminum powder and 150-grain diameter meshes) for water and oil (Super Mulpus 68). The effects of the Reynolds number on the laminar asymmetric flow structure in the flow region are studied. The induced speed distribution in the rotation of cylinder (diameter 10 mm) circumference has examined about the Reynolds number from 26 to 522 for water consequent cylinder rpm 10, 25, 50, 75, 100 and 0.12 to 2.32 for Super Mulpus 68 Oil consequent cylinder rpm 5, 10, 25, 50, 75, 100. The relation between the induced speeds after the time had passed enough and the various cylinder rotational speeds for both analytical and experimental results are shown. At lower Reynolds number experimental results are closer to theoretical results for a finite time condition, at that time there is exist vorticity around the cylinder. We can also establish that more difference between experimental and theoretical results with higher Reynolds number. An interesting phenomenon has been observed in the flow patterns at various Reynolds number and is discussed. Finally, authors have explained the significant difference between experimental and theoretical results and a new paradox has been introduced.

scholarly journals Transient fluid force on a rapidly rotating circular cylinder in a uniform flow.

1985 ◽  
Vol 51 (471) ◽  
pp. 3659-3664 ◽  
Author(s):  
Shigenori MATSUNAGA ◽  
Michihiro NISHI ◽  
Hiroshi TSUKAMOTO ◽  
Takashi YOSHITAKE ◽  
Mitsuru SHIMOGAKI
Keyword(s):  
Circular Cylinder ◽  
Uniform Flow ◽  
Fluid Force ◽  
Rotating Circular Cylinder
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