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Oscillations in Prandtl slope flow started from rest
Author(s) -
Fedorovich E.,
Shapiro A.
Publication year - 2016
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.2955
Subject(s) - prandtl number , buoyancy , mechanics , turbulent prandtl number , turbulence , laminar flow , momentum (technical analysis) , flow (mathematics) , physics , reynolds number , convection , nusselt number , finance , economics
We study oscillations that develop in flows along a uniform planar slope in an initially resting stratified fluid as a result of sudden application of a surface buoyancy flux. After an oscillatory adjustment (transition), the fluid reaches another steady state that corresponds to a stationary slope flow. The analysis is focused on the temporal evolution of the integral momentum and buoyancy structure in the laminar Prandtl‐type slope flow. The main questions addressed are related to physical conditions leading to emerging of the en masse oscillations in the transitioning slope flow, the frequency of these oscillations, and features of their temporal evolution. The persistence of oscillations in Prandtl‐type slope flows is found to be associated, somewhat paradoxically, with the fast temporal decay of the surface stress oscillations in the process of the stress approaching a constant value. This relatively rapid evolution of the surface stress progressively weakens damping of the integral momentum and buoyancy oscillations. Extensions of the analyses to the Prandtl slope flow driven by the surface buoyancy and to the turbulent slope flows are proposed and discussed.