Laboratory, Numerical, and Theoretical Modeling of the Flow
in a Far Wake in a Stratified Fluid

O. A. Druzhinin, V. V. Papko, D. A. Sergeev, and Yu. I. Troitskaya

Institute of Applied Physics, Russian Academy of Sciences, ul. Ul’yanova 46, Nizhni Novgorod, 603950 Russia
e-mail: druzhinin@hydro.appl.sci-nnov.ru

Received December 13, 2005; in final form, March 13, 2006

Abstract—The far-wake flow past a sphere towed in a fluid with high Reynolds and Froude numbers and with
a pycnocline-form salt-density stratification is studied in a laboratory experiment based on particle image
velocimetry and in numerical and theoretical modeling. In the configuration under consideration, the axis of
sphere towing is located under a pycnocline. Flow parameters, the profiles of density and average velocity, and
the initial field of velocity fluctuation in numerical modeling are specified from the data of the laboratory exper-
iment. The fields of fluid velocity at different times and the time dependences of integral parameters of wake
flow, such as the average velocity at the axis and the transverse width of the flow, are obtained. The results of
numerical modeling are in good qualitative and quantitative agreement with the data of the laboratory experi-
ment. The results of the laboratory experiment and numerical modeling are compared to the predictions of a
quasi-linear and quasi-two-dimensional theoretical model. The time evolution of both the average velocity at
the axis and the transverse width of the wake is obtained with the model and is in good agreement with the
experimental data. The results of numerical modeling also show that, under the effect of velocity fluctuation in
the wake, internal waves whose spatial period is equal to the characteristic period of the wake’s vortex structure
are excited efficiently in the pycnocline.

DOI: 10.1134/S0001433806050070

Pleiades Publishing home page | journal home page | top

If you have any problems with this server, contact webmaster.