Authors

Citation

Yx. Xu et al., MOTION FIELDS GENERATED BY THE OSCILLATORY MOTION OF A CIRCULAR-CYLINDER IN A LINEARLY STRATIFIED FLUID, Experimental thermal and fluid science, 14(3), 1997, pp. 277-296

Citations number

36

Language

INGLESE

art.tipo

Article

Categorie Soggetti

Engineering, Mechanical","Phsycs, Fluid & Plasmas",Thermodynamics

Journal title

ISSN journal

0894-1777

Volume

14

Issue

3

Year of publication

1997

Pages

277 - 296

Database

ISI

SICI code

0894-1777(1997)14:3<277:MFGBTO>2.0.ZU;2-0

Abstract

The motion field generated by either the horizontal or the vertical fi
nite-amplitude oscillation of a long right circular cylinder in a line
arly stratified fluid is investigated by a series of laboratory experi
ments; the oscillation frequencies considered cover a range both less
than and greater than the buoyancy frequency. The governing parameters
are shown to be the oscillation amplitude to cylinder diameter ratio
a/D, the oscillation frequency to buoyancy frequency ratio omega/N, an
d the viscous to buoyancy time-scale ratio T-vb = ND2/v (or the Stokes
number beta = omega D-2/V), where v is the kinematic viscosity of the
fluid. Flow regime diagrams are developed as functions of a/D and ome
ga/N for a fixed T-vb. The characteristic flow types for the horizonta
l oscillation case include weakly detached flow, localized mixing, lay
ering, and single intrusion, whereas the vertical oscillation leads to
weakly detached flow, localized mixing, and single and double intrusi
ons. Both oscillation directions lead to propagating internal waves wh
en omega/N < 1; the direction of the group velocity is observed to be
given by the angle sin(-1)(omega/N) to the horizontal axis, in accord
with linear theory. A nondiffusive numerical model is developed to inv
estigate the flow behavior during the initial stages of the cylinder o
scillations. The large-scale motion features obtained from the numeric
al model for the early flow development of the various flow regimes ar
e found to compare well with those of the laboratory experiments. (C)
Elsevier Science Inc., 1997.