The interaction of a self-propagating barotropic cyclonic vortex with an obstacle has been investigated and the conditions for a vortex to bifurcate into two vortices determined. In the present study we performed two sets of idealized laboratory experiments with the aim of investigating the importance of the obstacle horizontal cross sectional geometry and the influence of the height of the obstacle. As in a previous study, after a self-propagating cyclonic vortex came into contact with the obstacle, fluid peeled off the outer edge of the vortex and a so-called "streamer" went around the obstacle in a counterclockwise direction. Under certain conditions, this fluid formed a new cyclonic vortex in the wake of the obstacle, causing bifurcation of the original vortex into two vortices. In the present study experiments performed using an obstacle with an elliptical horizontal cross section revealed that the relevant parameter governing the occurrence of bifurcation is the length which the "streamer" has to travel around the obstacle, and not the dimension of the obstacle in the direction orthogonal to the motion of the vortex. In addition, the present results suggest that bifurcation occurs only when the obstacle height is equal or larger than 0.85 % of the vortex height. Observations of a "Meddy" bifurcating after colliding with the Irving Seamount in the Canary Basin show behavior similar to these idealized laboratory experiments. This suggests that these results could be used to explain and predict the outcome of a vortex colliding with seamounts of varying geometry in the ocean.
Adduce, C., Cenedese, C. (2004). Experimental investigation of a vortex interacting with an obstacle in a rotating fluid. In XXIX Convegno di Idraulica e Costruzioni Idrauliche (pp.5-12). COSENZA : Editore Bios.
Experimental investigation of a vortex interacting with an obstacle in a rotating fluid
ADDUCE, Claudia;
2004-01-01
Abstract
The interaction of a self-propagating barotropic cyclonic vortex with an obstacle has been investigated and the conditions for a vortex to bifurcate into two vortices determined. In the present study we performed two sets of idealized laboratory experiments with the aim of investigating the importance of the obstacle horizontal cross sectional geometry and the influence of the height of the obstacle. As in a previous study, after a self-propagating cyclonic vortex came into contact with the obstacle, fluid peeled off the outer edge of the vortex and a so-called "streamer" went around the obstacle in a counterclockwise direction. Under certain conditions, this fluid formed a new cyclonic vortex in the wake of the obstacle, causing bifurcation of the original vortex into two vortices. In the present study experiments performed using an obstacle with an elliptical horizontal cross section revealed that the relevant parameter governing the occurrence of bifurcation is the length which the "streamer" has to travel around the obstacle, and not the dimension of the obstacle in the direction orthogonal to the motion of the vortex. In addition, the present results suggest that bifurcation occurs only when the obstacle height is equal or larger than 0.85 % of the vortex height. Observations of a "Meddy" bifurcating after colliding with the Irving Seamount in the Canary Basin show behavior similar to these idealized laboratory experiments. This suggests that these results could be used to explain and predict the outcome of a vortex colliding with seamounts of varying geometry in the ocean.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
