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 rotating homogeneous fluid has been investigated. Particle streak and dye photographs are presented (i) to demonstrate the complex three-dimensional flow fields generated by the discharge and (ii) to illustrate how the structure and time development of the flow field is controlled by the momentum ( M ) and buoyancy ( B ) fluxes of the discharge, the lateral location y * of the discharge source from the container wall and the rotation rate Ω of the system. The effects of background rotation are studied by contrasting flow patterns for rotating and non-rotating cases, with all other parameters being kept fixed. For cases in which the system is rotating, measurements of momentum-dominated and buoyancy-dominated discharges reveal that the downstream position x p and streamwise dimension L p of the primary anticyclonic eddy corner circulation (formed by the deflection to the right of the descending jet) depend primarily upon the dimensionless distance y * / W (where W is the width of the channel). The influences of the dimensionless time Ω t and the relevant Coriolis parameter M Ω/ B on x p and L p are shown to be relatively weak. The counterpart dimensions L s and x s of the secondary cyclonic eddy (generated by the shear associated with (i) the primary eddy and (ii) a boundary current formed along the right side wall of the channel) increase with time. Both dimensions are shown to scale satisfactorily with the inertial scale u 0 /Ω and the buoyancy/Coriolis scale g ′/Ω 2 , where u 0 and g ′ are the source discharge velocity and the modified gravitational acceleration, respectively. The speed u N of the nose of the wall boundary current is shown to be determined primarily by the dimensionless parameter M Ω/ B ; for values of M Ω/ B greater than about 5, the quantity u N is determined primarily by the discharge velocity at the source. For values of M Ω/ B less than about 5, the dimensionless nose velocity u N Ω/ g ′ increases monotonically with increasing M Ω/ B for all values of y * / W .