The influence of the staggering position of a rotating rod on flow past a main circular cylinder is investigated numerically. The rod is rotated at a constant speed ratio of 3. The effect of the diameter ratio of the rotating rod is studied by considering two different diameter ratios. The investigation is carried out at a fixed pitch length of 1. The study is carried out for two Reynolds number, viz., 100 and 500. The momentum injection from the rod is found to alter the flow characteristics behind the main cylinder. For a certain arrangement of stagger angle and diameter ratio, the vortex shedding behind the main cylinder gets suppressed. The corresponding configuration for which minimum drag coefficient is achieved is suggested from this study. Copyright © 2008 by ASME.

S. Vengadesan

Department of Applied Mechanics

Circular cylinders

Drag

Mobile telecommunication systems

Reynolds number

Rotation

Vortex shedding

CONSTANT SPEED

DIAMETER RATIO

flow characteristics

MOMENTUM INJECTION

On flow

PITCH LENGTH

Reynolds (CO)

ROTATING RODS

STAGGER ANGLE

Cylinders (shapes)

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Influence of Staggering Angle of a Rotating Rod on Flow Past a Circular Cylinder

Journal of Fluids Engineering, Transactions of the ASME

Two-dimensional flow over a circular cylinder placed in-line behind a control rod of the same diameter is studied with and without the influence of a plane wall. Thermal patterns observed during various vortex shedding modes are discussed in detail. POD analysis of temperature data reveals that, with the decrease in wall height, modal structures are moved closer to the cylinder surface, which increases the heat transfer fluctuation. The plane wall increases the heat transfer from the bottom surface of the cylinder and decreases the heat transfer from the top surface, while the rotation of control rod contributes in an opposite manner. As the cylinder is moved closer to the wall, the time-averaged Nusselt number increases for a stationary control rod. In the case of a rotating control rod, the rotation of the control rod acts in the opposite sense to nullify this wall effect. © 2014 Taylor & Francis Group, LLC.

Numerical Heat Transfer; Part A: Applications

Heat transfer characteristics of flow over a circular cylinder with an upstream control rod in wall vicinity

The influence of rounded corners on the aerodynamic forces and flow interference has been studied in detail for a uniform flow past two side-by-side arranged square cylinders. The Reynolds number (Re) based on the cylinder diameter (D) and free stream velocity (U) is 100. Numerical simulations are carried out for seven different transverse gap ratios (T/D), each with a minimum and maximum corner radius. An inbuilt finite difference code with staggered arrangement of flow variables is used to discretize the governing equations. The concept of immersed boundary method (IBM) is employed to simulate flow around rounded corners using the regular Cartesian grids. The computational code was validated for flow past an isolated circular cylinder, square cylinder, and two equal sized circular cylinders and the results were found to be in very good agreement with available literatures. In the present study, results in terms of the mean and rms values of lift and drag coefficients, Strouhal number, phase diagrams, and contours of streamlines and vorticity are presented. As the corner radius is increased, a reduction in the drag force is observed. There exists a significant effect of gap ratio and corner radius on the phase angle of lift and drag coefficients. Three different flow patterns, namely the single bluff body flow, biased gapside flow, and two independent bluff body flows, were observed from this study. © 2012 by ASME.

Influence of rounded corners on flow interference due to square cylinders using immersed boundary method

Influence of staggering angle of a rotating rod on flow past a circular cylinder

Journal of Fluids and Structures

Hydrodynamic forces on dual cylinders of different diameters in steady currents

Flow, Turbulence and Combustion

Drag Reduction of a Circular Cylinder Using an Upstream Rod

Applied Ocean Research

Numerical simulation of viscous flow past two circular cylinders of different diameters

International Journal for Numerical Methods in Fluids

Numerical predictions of low Reynolds number flows over two tandem circular cylinders

Journal	Journal of Fluids Engineering, Transactions of the ASME
ISSN	00982202
Open Access	No