A note on the dynamics of small-scale fronts

Publisher Website
Google Scholar
Abstract
The motion of small-scale, non-rotating, surface fronts is discussed. A hydraulic approach is known to give a good first order solution for the frontal velocity. A buoyancy-conserving integral model for the secondary circulation induced by mixing, giving convergence of surface water towards the front, is superposed and it is found that the reduction of the frontal velocity caused by this circulation is dependent upon the value of the critical Richardson number, Ri c. For Ri c ≈ 0.1 the frontal velocity is decreased by about 10% compared to the hydraulic frontal velocity. The hydraulic model used in this paper is an extension of the work by Stommel and Farmer (1953). Thus the hydraulic velocity of the front is supposed to be determined in a control section behind the current head. The head has no dynamical importance for the hydraulic velocity. This view is opposite to the classical one where the dynamics of the head itself are believed to govern the hydraulic front velocity. The hydraulic model is also compared with some laboratory results on arrested bottom gravity currents, obtained by Britter and Simpson (1978). with convincing results.

This publication has 10 references indexed in Scilit: