Harmonic oscillations of a circular cylinder moving with constant velocity in a quiescent fluid

Jan Novaes Recicar,Miguel Hiroo Hirata,Luiz Antonio Alcântara Pereira

doi:10.5585/exacta.v6i1.663

Abstract

The flow around an oscillating circular cylinder which moves with constant velocity in a quiescent Newtonian fluid with constant properties is analyzed. The influences of the frequency and amplitude oscillation on the aerodynamic loads and on the Strouhal number are presented. For the numerical simulation, a cloud of discrete Lamb vortices are utilized. For each time step of the simulation, a number of discrete vortices are placed close to the body surface; the intensity of theirs is determined such as to satisfy the no-slip boundary condition.

Highlights

Understanding and being able to analyze the flow around an oscillating body which moves with constant velocity in a quiescent fluid with constant properties is of great fundamental and practical importance in aero and hydrodynamics analysis
The results presented in line 4, as well as all the other results presented elsewhere in this paper were obtained carrying out the simulations with M=50 sources panels to replace the cylinder surface and lasted for t = 40 dimensionless time
The three-dimensional effects present in the experiments are very important for the Reynolds number used in the simulations

Summary

Introduction

Understanding and being able to analyze the flow around an oscillating body which moves with constant velocity in a quiescent fluid with constant properties is of great fundamental and practical importance in aero and hydrodynamics analysis. The oscillatory motion of small amplitude mainly modifies the near field changing the boundary layer flow and, as a consequence, having an important effect on the aerodynamic forces and the pressure distribution. This paper deals with the analysis of a body oscillating around a fixed position which is located in an incoming uniform flow with constant velocity; to simplify matters the oscillatory motion is restricted to heave. A simpler approach to the present problem would consider a fixed body located in an oscillating incoming flow; notice, that with this approach the whole fluid mass would oscillate with the same frequency and amplitude, which is not quite what, happens in real situations, mainly in the far field region. In Type III – high frequency of cylinder oscillation – the vortex shedding frequency is locked-in with the cylinder oscillation frequency

Definitions

Governing equations

Viscous splitting algorithm and aerodynamics loads

Convection and diffusion of vorticity

Numerical implementation

Results

Conclusions