Abstract
The linear and nonlinear growth of longitudinal vortices in a laminar boundary layer
and the development of secondary instabilities are investigated theoretically and by
experiment. As a prototype problem the natural convection flow along a constant-heat-flux
inclined flat plate in water is chosen. Based upon the smallness of the
plate's angle of inclination from the vertical, the largeness of the Grashof number,
and the smallness of the vortex strength, a perturbation method is used to derive
and solve a consistent set of governing equations for the linear, weakly nonlinear and
the strongly nonlinear regimes which is asymptotically correct to first order. Liquid-crystal
thermography based on wide-band liquid crystals is used to provide full-field,
highly accurate wall temperature measurements and visualizations.The spanwise periodic thickening and thinning of the boundary layer through a
nonlinear, but steady, vortex growth is seen to be responsible for practically all of
the increase of mean heat transfer values during the laminar–turbulent transition.
Secondary instabilties in the form of sinuous and varicose unsteady wave modes
and the steady merging of vortices are visualized but are seen to have only a minor
additional influence on mean heat transfer.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
25 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献