Our understanding of the general ocean circulation has been enhanced by an interplay between laboratory model, analytic and numerical theory. Unfortunately (for experimenters), however, it is now generally thought that there is no longer a role for laboretory models of the ocean circulation : The role has ended long befor. Is this true? With this question in mind, the author presents a brief review of previous laboratory experiments on the general ocean circulation and a critical evaluation of those experimental efforts. Some new results from recent laboratory models are also described.

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An encapsulated drop made of an outer liquid and an inner gas has recently become a subject of special interest. If the encapsulated drop can be simply and sequentially produced, it may improve functional liquid films for chemical reactors or light weight structural materials for spacecraft. The hydrodynamic mechanism of encapsulated drop formation in liquid-liquid-gas systems which has a relatively simple structure and an easy control system, is described experimentally and theoretically. The influence of gas flow rate and liquid physical properties on the size, the generation frequency and the thickness of encapsulated drops has been investigated to confirm the possibility of producing encapsulated drops in this system. Furthermore, the flow patterns around a moving encapsulated drop were studied numerically by solving the steady, incompressible Navier-Stokes equations. The accelerated motion, drag coefficient of the encapsulated drop and so on were also investigated.

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Numerical predictions of flow behavior of a non-Newtonian fluid in converging-diverging circular channel were carried out using a finite difference technique with a generalized coordinate system. The constitutive equation adopted was the Oldroyd-B model of the differential equation form. It was assumed that flow is incompressible, and steady in the channel where the axial velocity is parabolic at the inlet and fully developed at the outlet, and no-slip condition is used at the channel wall. In the calculation flow velocity and the associated stress distribution were obtained by solving the vorticity transport equation and the Poisson equation together with the constitutive equation by S. O. R. technique using different accelaration factors. The pressure distribution was also calculated by solving the pressure equation using the resultant flow field solutions. The calculation results indicate that the flow field characteristics are different from those of Newtonian flow; the circulation zone in the diverging channel part is slightly sifted toward downstream when the non-Newtonian model is affected. Pressure drop excess and overshoot are present along the wall due to the appearance of the normal stress component in a case of non-Newtonian fluid. A qualitative agreement was achieved with the published results in a periodically constricted channel.

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Two-dimensional selective withdrawals in an incompressible continuously stratified fluid are studied. Longer evolutions than the solutions obtained by Pao and Kao for the flows of very small internal Froude numbers are given, which indicates that several eddy regions of cell structures are developed in the stagnant layer. The effect of the end wall for the case in which the source is located at the point detached the wall is investigated by superposing flow fields due to two sinks. The validity of the theoretical solutions is confirmed by a numerical analysis, and the limitation of the linear analysis is also clarified.

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It is shown that both ordinary and retrograde fluids with phase transition can be described by supplementing a specific heat at constant pressure expressed by a quadratic equation of temperature to van der Waals' equation of state. Expressions for heat of vaporization, specific heat, internal energy and entropy are provided for such a fluid. Then, Rankine-Hugoniot's relation is derived and the solutions for evaporation and condensation discontinuities satisfying entropy condition are calculated from intersection with Rayleigh line, and thereby possible types of discontinuities and their properties are discussed. Their evolutionarity as one-dimensional wave and their difference from detonation and defragration waves are discussed.

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