Ice jam initiation by a simple partial su~face obstruction in a channel was studied experimentally inlaboratory fluniesusingpolyethylene, paraffin, as well asreal ice parallelepipeds, as model ice floes. The important dependent parameter under study was the critical s u~f x e concentration of floes at the gap in the surface obstruction at which floes would form a stable arch across the gap and an icejam would be initiated. Thiscritical floe concentration C, " was found to be independent of the ratio of gap width to flume width and to be a decreasing power function of the ratio of floe size to gap width. In addition C," was found to be independent of the approach flow Froude number for flow velocity less than the critical submergence velocity of an ice floe, for artificial model floes, but to increase with increasing Froude number when real ice floes were used. This difference and other quantitatively different results depending on whether natural ice blocks o r plastic blocks wel-e used as model ice floes were lentatively attributed to differences in floe materinlcharacte~.istics, mainly intel-particle friction force and su~face tension property, the latter affecting significantly the critical submergence velocity of thin plastic blocks ascompared to that of natul-al ice floes of the same size and density.On presente les rCsultatsd'uneetude en laboratoire du processusde Cormation d'un emblcledil A une obstruction supe~ficielle partielle dans un canal hydraulique. Le parnnktre caractCristique est laconcentration de glqonsdans le passage au droit de I'obstacle oil les glaqons s'accumulent par effet d'arc-boutement pour former un embide. On a determine que cette concentration critique, C,":, Ctait independante du ~xpport entre la largeur de I'ouverture et Ialargeul-du canal, et etait unefonctionde p~~issancedCcroissantedu rapport entre lat;iilledesgla~onset lalargeurde I'ouverture. De plus. C," s'est revel6 independant du nombre de Froude de I'ecoulernent amont clans les essais rialises avec cles "glqons" artificiels, mais il est par ailleui-s une fonction croissante du non~bre de Froude dans les essais rCalises avec de vl-ais g l a~o n s .Cette difference ainsique d'autres variations dans les resultatsobtenus suivant qtle lesglqons ont 6te sirnul6s par des blocs de plastique ou de glace sont attribuees. du rnoins tempolairement, aux differences entre les propriites physiques du plnstique et de laglace, telles les forces de frottement interparticulaires et les proprietes de tension supe~ficielle. Cette derniere propritte peut en pal-ticulier iyxndement affectes la vitesse d'inmersion d'un bloc mince de plastique par rapport B celle d'un glaqon de mernes dimensions et densite.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.