Laboratory experiments were carried out to investigate the effects of rotation on turbulent convection. The experimental facility was a bottom-heated, water-filled, cubical tank mounted on a turntable. The investigations were performed over a wide range of bottom buoyancy fluxes qo and rotation rates Q, including sd = 0; qo and Q were held constant during each experiment. The depth of the water column H was fixed for the entire experimental programme. For the non-rotating experiments, the r.m.s. velocity fluctuations were found to scale well with the convective velocity w* = (qoH)i, while the mean and r.m.s. fluctuations of buoyancy were found to scale with qo/w*. The spectra of temperature fluctuations were measured and were used to assess the applicability of two types of scaling, one of which is advanced in the present study.For the rotating experiments, the convective-layer growth is affected by the rotation a t a height h, x 4.5(q0 The r.m.s. horizontal velocity of the rotationally affected mixed layer is uniform throughout the mixed layer and is given by (.l")i x 1.7(qOQ-')4. The time growth law of the mixed-layer thickness h,, when h, > h,, is given by h, x 0.7(q0Q-3)iQt, where t is the time. The rotational effects become important when the Rossby number is given by Ro = (u'2)1/QZr x 1.5, where the integral lengthscale is estimated as 1, x 0.25hC.The mean buoyancy gradient in the mixed layer was found to be much higher than in the corresponding non-rotating case, and the r.m.s. fluctuations and mean buoyancies were found to scale satisfactorily with (qo Q)t. A spectral form for the temperature fluctuations in rotating convection is also proposed and is compared to the experimental results.

The flow of a linearly stratified fluid past a sphere is considered experimentally in the Froude number Fi, Reynolds number Re, ranges 0.005 ≤ Fi ≤ 20 and 5 ≤ Re ≤ 10000. Flow visualization techniques and density measurements are used to describe the rich range of characteristic flow phenomena observed. These different flow patterns are mapped on a detailed Fi against Re flow regime diagram. In most instances the flow patterns were found to be very different from those observed in homogeneous fluids. Vortex shedding characteristics, for example, were found to be dramatically affected by the presence of stratification. Where possible, the results are compared with available analytical and numerical models.

[1] The circulation in Blanes canyon, an interruption in the NW Mediterranean continental shelf north of Barcelona, was investigated. The study employs data from oceanographic surveys carried out in the summer and fall of 2003. Velocity data show that in the vicinity of the shelf break the flow is deflected along the canyon walls. A cyclonic mean flow can be seen over the canyon mouth owing to vortex stretching of fluid parcels advected across the shelf break. Field observations are in qualitative agreement with fundamental fluid dynamic considerations based on potential vorticity conservation and friction effects at lateral boundaries. Evidence is given that upwelling is found near the shelf break inside the canyon in the two field experiments. This upwelling extends vertically from the seasonal thermocline (at about 100 m) to the shelf-slope front (at about 200 m). There is no evidence that upwelled water can reach the continental shelf.

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