The dynamics of strong turbulence at free surfaces. Part 2. The boundary conditions

M Brocchini, DH Peregrine

Research output: Contribution to journalArticle (Academic Journal)peer-review

92 Citations (Scopus)

Abstract

Strong turbulence at a water–air free surface can lead to splashing and a disconnected surface as in a breaking wave. Averaging to obtain boundary conditions for such flows first requires equations of motion for the two-phase region. These are derived using an integral method, then averaged conservation equations for mass and momentum are obtained along with an equation for the turbulent kinetic energy in which extra work terms appear. These extra terms include both the mean pressure and the mean rate of strain and have similarities to those for a compressible fluid. Boundary conditions appropriate for use with averaged equations in the body of the water are obtained by integrating across the two-phase surface layer. A number of ‘new’ terms arise for which closure expressions must be found for practical use. Our knowledge of the properties of strong turbulence at a free surface is insufficient to make such closures. However, preliminary discussions are given for two simplified cases in order to stimulate further experimental and theoretical studies. Much of the turbulence in a spilling breaker originates from its foot where turbulent water meets undisturbed water. A discussion of averaging at the foot of a breaker gives parameters that may serve to measure the ‘strength’ of a breaker.
Translated title of the contributionThe dynamics of strong turbulence at free surfaces. Part 2. The boundary conditions
Original languageEnglish
Pages (from-to)255 - 290
Number of pages36
JournalJournal of Fluid Mechanics
Volume449
DOIs
Publication statusPublished - 12 Dec 2001

Bibliographical note

Publisher: Cambridge University Press

Fingerprint Dive into the research topics of 'The dynamics of strong turbulence at free surfaces. Part 2. The boundary conditions'. Together they form a unique fingerprint.

Cite this