High-mode stationary waves in stratified flow over large obstacles

Type : ACL
Nature : Production scientifique
Au bénéfice du Laboratoire : Non
Statut de publication : Publié
Année de publication : 2010
Auteurs (3) : KLYMAK Jody,m LEGG S PINKEL R
Revue scientifique : Journal of Fluid Mechaniscs
Volume : 644
Fascicule :
Pages : 321-336
DOI : 10.1017/S0022112009992503
URL : -
Abstract : Simulations of steady two-dimensional stratified flow over an isolated obstacle are presented where the obstacle is tall enough so that the topographic Froude number, Nh(m)/U(0) >> 1. N is the buoyancy frequency, h(m) the height of the topography from the channel floor and U(o) the flow speed infinitely far from the obstacle. As for moderate Nh(m)/U(0) (similar to 1), a columnar response propagates far up- and downstream, and an arrested lee wave forms at the topography. Upstream, most of the water beneath the crest is blocked, while the moving layer above the crest has a mean velocity U(m) = U(o)H/(H - h(m)). The vertical wavelength implied by this velocity scale, lambda(o) = 2 pi U(m)/N, predicts dominant vertical scales in the flow. Upstream of the crest there is an accelerated region of fluid approximately lambda(o) thick, above which there is a weakly oscillatory flow. Downstream the accelerated region is thicker and has less intense velocities. Similarly, the upstream lift of isopycnals is greatest in the first wavelength near the crest, and weaker above and below. Form drag on the obstacle is dominated by the blocked response, and not on the details of the lee wave, unlike flows with moderate Nh(m)/U(o).
Mots-clés : DOWNSLOPE WINDSTORMS; KNIGHT INLET SILL; LEE WAVES; MOUNTAIN-WAVE; RIDGE; TOPOGRAPHY; TURBULENCE
Commentaire : Times Cited in Web of Science Core Collection: 47
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Citation :
Klymak JM, Legg S, Pinkel R (2010) High-mode stationary waves in stratified flow over large obstacles. J Fluid Mech 644: 321-336 | doi: 10.1017/S0022112009992503