Dynamics of Flow Around a Cylinder Oscillating In-Line for Low Reynolds Numbers

2010 ◽  
Author(s):  
L. Baranyi ◽  
K. Huynh ◽  
N. W. Mureithi
Keyword(s):  
Reynolds Number ◽  
Oscillation Amplitude ◽  
Wake Flow ◽  
Computational Domain ◽  
Cylinder Wake ◽  
Mean Values ◽  
Reynolds Number Flow ◽  
Lower Amplitude ◽  
Low Reynolds ◽  
Wake Modes

This study builds on an earlier study of low-Reynolds number flow about a cylinder forced to oscillate in-line with the main flow, which found vortex switches at some oscillation amplitude values. Here we extend the Reynolds number domain to Re = 60–350, utilize a computational domain characterized by R2/R1 = 360, and do computations at two frequency ratios of f/St0 = 0.8 and 0.9. Computations were carried out using a thoroughly tested finite-difference code. Some results were compared with those obtained by Ansys CFX, and good agreement was found. When plotted against oscillation amplitude, rms and time-mean values of force coefficients revealed a shift toward lower amplitude with higher Re. Findings for the effect of frequency ratio are similar. Where vortex switches occurred, a pre- and post-jump analysis is carried out. POD analysis of the cylinder wake flow field is employed to reveal the detailed wake dynamics as the forcing parameters are varied. The analysis provides further details on the transition of the dominant wake modes in response to the symmetry breaking bifurcation underlying the vortex switches observed in the simulations.

Simulation of Low-Reynolds Number Flow Around a Circular Cylinder Following a Slender Elliptical Path

2013 ◽  
Author(s):  
László Baranyi
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Amplitude Ratio ◽  
Oscillation Amplitude ◽  
Base Pressure ◽  
Reynolds Number Flow ◽  
Two Dimensional Flow ◽  
Number Flow ◽  
Low Reynolds ◽  
Lock In

Two-dimensional flow around a circular cylinder forced to follow an elliptical path at low Reynolds numbers is investigated numerically using a thoroughly tested in-house code based on the finite difference method. Time-mean (TM) and rms values of lift, drag and base pressure coefficients are investigated within the lock-in region against the transverse oscillation amplitude for Reynolds number Re = 150 at frequency ratios of 0.8, 0.9 and 1.0 while the ratio of in-line and transverse cylinder oscillation amplitudes is kept at six different values yielding slender elliptical cylinder paths. The objective of the paper is to investigate the effect of the shape of the path, or amplitude ratio, on force coefficients. Findings show that for the cases investigated the rms of lift and TM of drag and base pressure are hardly affected by the amplitude ratio, while its effects are pronounced on the TM of lift and rms of drag and base pressure.

Low Reynolds number flow around and heat transfer from a heated circular cylinder

2010 ◽  
Vol 1 (1-2) ◽  
pp. 15-20 ◽  
Author(s):  
B. Bolló
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Reynolds Number Flow ◽  
Two Dimensional Flow ◽  
Number Flow ◽  
Low Reynolds ◽  
Increasing Temperature

Abstract The two-dimensional flow around a stationary heated circular cylinder at low Reynolds numbers of 50 < Re < 210 is investigated numerically using the FLUENT commercial software package. The dimensionless vortex shedding frequency (St) reduces with increasing temperature at a given Reynolds number. The effective temperature concept was used and St-Re data were successfully transformed to the St-Reeff curve. Comparisons include root-mean-square values of the lift coefficient and Nusselt number. The results agree well with available data in the literature.

Low Reynolds number flow past a transverse cylinder at Mach two.

AIAA Journal ◽  
1972 ◽  
Vol 10 (10) ◽  
pp. 1381-1382
Author(s):  
CLARENCE W. KITCHENS ◽  
CLARENCE C. BUSH
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Flow Past ◽  
Number Flow ◽  
Low Reynolds

Numerical investigations on dynamic stall of low Reynolds number flow around oscillating airfoils

2010 ◽  
Vol 39 (9) ◽  
pp. 1529-1541 ◽  
Author(s):  
Shengyi Wang ◽  
Derek B. Ingham ◽  
Lin Ma ◽  
Mohamed Pourkashanian ◽  
Zhi Tao
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Dynamic Stall ◽  
Numerical Investigations ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
Low Reynolds

Optimal motion control of three-sphere based low-Reynolds number swimming microrobot

Robotica ◽  
2021 ◽  
pp. 1-17
Author(s):  
Hossein Nejat Pishkenari ◽  
Matin Mohebalhojeh
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Optimal Controller ◽  
Optimal Motion ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Three Sphere ◽  
Low Reynolds Number Swimming ◽  
Number Flow ◽  
Low Reynolds

Abstract Microrobots with their promising applications are attracting a lot of attention currently. A microrobot with a triangular mechanism was previously proposed by scientists to overcome the motion limitations in a low-Reynolds number flow; however, the control of this swimmer for performing desired manoeuvres has not been studied yet. Here, we have proposed some strategies for controlling its position. Considering the constraints on arm lengths, we proposed an optimal controller based on quadratic programming. The simulation results demonstrate that the proposed optimal controller can steer the microrobot along the desired trajectory as well as minimize fluctuations of the actuators length.

Sign in / Sign up

Export Citation Format

Share Document