LABORATORY STUDIES OF A ROUND, NEGATIVELY BUOYANT JET DISCHARGED HORIZONTALLY INTO A ROTATING HOMOGENEOUS FLUID

Results of laboratory experiments are described in which the motion of a round negatively buoyant jet discharged horizontally into a rotatin g homogeneous fluid has been investigated. Particle streak and dye pho tographs are presented (i) to demonstrate the complex three-dimensiona l flow fields generated by the discharge and (ii) to illustrate how th e structure and time development of the flow field is controlled by th e momentum (M) and buoyancy (B) fluxes of the discharge, the lateral l ocation y of the discharge source from the container wall and the rot ation rate Omega of the system. The effects of background rotation are studied by contrasting flow patterns for rotating and non-rotating ca ses, with all other parameters being kept fixed. For cases in which th e system is rotating, measurements of momentum-dominated and buoyancy- dominated discharges reveal that the downstream position x(p) and stre amwise dimension L(p) of the primary anticyclonic eddy corner circulat ion (formed by the deflection to the right of the descending jet) depe nd primarily upon the dimensionless distance y/W (where W is the widt h of the channel). The influences of the dimensionless time Omega t an d the relevant Coriolis parameter M Omega/B on x(p) and L(p) are shown to be relatively weak. The counterpart dimensions L(s) and x(s) of th e secondary cyclonic eddy (generated by the shear associated with (i) the primary eddy and (ii) a boundary current formed along the right si de wall of the channel) increase with time. Both dimensions are shown to scale satisfactorily with the inertial scale u(0)/Omega and the buo yancy/Coriolis scale g'/Omega(2), where u(0) and g' are the source dis charge velocity and the modified gravitational acceleration, respectiv ely. The speed u(N) of the nose of the wall boundary current is shown to be determined primarily by the dimensionless parameter M Omega/B; f or values of M Omega/B greater than about 5, the quantity u(N) is dete rmined primarily by the discharge velocity at the source. For values o f M Omega/B less than about 5, the dimensionless nose velocity u(N) Om ega/g' increases monotonically with increasing M Omega/B for all value s of y/W.