George_Kay2.pdf (4.02 MB)
Download file

Warm discharges in cold fresh water: 2. Numerical simulation of laminar line plumes

Download (4.02 MB)
journal contribution
posted on 22.06.2016, 11:10 by Alabodite M. George, Anthony Kay
The behaviour of a discharge of warm water upwards into a homogeneous body of cold fresh water was investigated by means of a numerical model. The discharge has a parabolic velocity profile, with Reynolds number Re = 50, Prandtl number Pr = 7 and Froude number varied over the range 0:2 Fr 2:5. Water density is taken to be a quadratic function of temperature, so that an initially positively buoyant discharge will experience buoyancy reversal as it mixes with an ambient below the temperature of maximum density. The resulting plume has some similarities to a fountain resulting from injection of negatively buoyant fluid upward into a less dense ambient. The plume is initially symmetric, but then its head detaches as it approaches its maximum height. The detached head is denser than the fluid in the plume below it, and the interaction between the sinking head and the rising plume causes a sideways deflection; as this cycle is repeated, the plume displays side-to-side flapping motion and vertical bobbing. As Froude number is increased (i.e. buoyancy reduced) the growth of the plume becomes slower, but the plume eventually reaches a greater height. We obtain empirical power-law scalings for maximum height and time taken to reach that height as functions of Froude number; these scalings are simlar to those for fountains with a linear dependence of density on temperature in the very weak regime.

History

School

  • Science

Department

  • Mathematical Sciences

Published in

Environmental Fluid Mechanics

Citation

GEORGE, A. and KAY, A., 2017. Warm discharges in cold fresh water: 2. Numerical simulation of laminar line plumes. Environmental Fluid Mechanics, 17 (2), pp. 231–246.

Publisher

© Springer

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2017

Notes

The final publication is available at Springer via http://dx.doi.org/10.1007/s10652-016-9468-x

ISSN

1567-7419

eISSN

1573-1510

Language

en