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The countergradient heat flux in turbulent stratified flows

Schumann, U. (1987) The countergradient heat flux in turbulent stratified flows. Nuclear Engineering and Design, 100, pp. 255-262. DOI: 10.1016/0029-5493(87)90078-1.

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Official URL: http://www.elsevier.com/wps/find/journaldescription.cws_home/505661/description#description

Abstract

Countergradient heat flux (CGHF) transports heat from low to high temperature regions. The reasons for this paradoxial behaviour are explained in this paper. We report on three examples for which CGHF has been observed either experimentally or in direct numerical simulations. The examples concern vertical heat flux in convective or stably stratified layers with or without shear. It is shown that CGHF arises in stably stratified parts of the flow if the dissipation of temperature fluctuations is too small to balance source terms for such fluctuations. In such cases, CGHF converts potential energy into kinetic energy. By means of an eigenanalysis of a second order model we support this explanation and show that CGHF appears in particular for high Prandtl number flows.

Document Type:Article
Title:The countergradient heat flux in turbulent stratified flows
Authors:
AuthorsInstitution or Email of Authors
Schumann, U.UNSPECIFIED
Date:1987
Journal or Publication Title:Nuclear Engineering and Design
Volume:100
DOI:10.1016/0029-5493(87)90078-1
Page Range:pp. 255-262
Status:Published
Keywords:CGHF
HGF - Research field:other
HGF - Program:other
HGF - Program Themes:other
DLR - Research area:no assignement
DLR - Program:no assignment
DLR - Research theme (Project):other
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Deposited By: Jana Freund
Deposited On:20 Feb 2008
Last Modified:12 Dec 2013 20:29

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