Laboratory results are described on the patterns of some elementary types of stratified flows, gravity flows in a two-layer fluid, and stratified wake flows past bluff bodies. Flow-visualization techniques were used extensively in making the experiments on these flows. Illustrative photographs of the flow patterns are included here. Some of the recent advances in the study of stratified flows are also reviewed briefly.

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Some examples of the results of visual observations on irregular fluid motions are shown, and the relation between the theory of chaos and irregular fluid motions is discussed.

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When a “normal” shock wave is introduced into a duct by controlling the upstream or back pressure, it interacts with the boundary layer which develops along the duct. In the case that the interaction is significant, the shock no longer remains a single normal shock, but gives way to a complex pattern of multiple shocks closely following one another. Such a multi-shock system is called a pseudo-shock wave.
A review is given on the pseudo-shock waves. Some characteristics such as the pressure recovery, the length, and the oscillation of a pseudo-shock are discussed, and the flow models presented so far are explained. Pseuso-shocks may appear anywhere in ducts and passages where normal shocks are supposed to stand and interact with wall boundary layers. Some of these examples are also described.

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This article reviews reflection and transmission of a shallow water soliton incident upon a boundary or an obstruction such as a sloping beach, a stepped bottom or a submerged barrier. Introducing a concept of edge-layer, the matched asymptotic expansion method is applied to obtain uniformly valid solutions throughout the whole region. The matching condition yields a 'reduced' boundary condition to be imposed on the Boussinesq equation in the shallow-water region extending on the outside of the edge-layer. Explicit matching procedure is demonstrated in detail for the sloping beach and is briefly described for the step and the barrier. Solving the Boussinesq equation (s) under the 'reduced' boundary condition (s) thus derived, reflection (and transmission) is discussed for the three typical bottom topography.

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The minimum size of devices integrated in LSI (Large Scale Integrated Circuit) is reduced every year. It will be as small as 0.1μm in the near future. In the course of developing such small devices, physical limitations or quantum effects are predicted to play an important role. The purpose of this article is to stress the importance of fluid mechanics for future LSI processing. It will be accomplished through the explanation of some topics in semiconductor processing, waiting for analyses based on fluid mechanics. These topics cover cleaning, oxidation, chemical vapor phase deposition, reflow of thin films, uniformity of coated films, and air flow in the clean room.

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For the purpose of applying the fundamental expressionE²=A+BU^0.5of the hot-wire anemometry to the flow accompanied by temperature fluctuations, the hot-wire characteristicsAandBare experimentally determined as the functions of the flow temperature Θ and the hot-wire temperature Θ_w. As the results, in accordance with the analysis based on Kramers' relation (reference 4), it is found that bothAandBare expressed as linear functions with respect to Θ and as quadratic functions with respect to Θ_w.

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This paper is concerned with the averaged nearshore circulation caused by waves breaking around a elliptical island. The equations of mean motion are derived for the elliptical island and the Poisson equation is obtained by using the stream function Ψ. This equation is applied to the volcanic island Iwo-jima and is solved numerically by finite differences. The obtained mean circulation patterns now enables us to predict the littoral process. In order to determine the wave field, the equation of wave refraction for the elliptical island is obtained by Fermat's principle without bottom friction.

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Numerical experiment on breakdown of KAM tori is carried out for the motion of a simple pendulum.
As a time step of the difference equation increases, integral curve in the phase plane for a certain fixed initial value deviates from the exact solution until it diverges.
Whole curve of a periodic solution is mapped into a rather curious figure with a few blank regions, before it diverges for larger time steps.
Comparison with the simple harmonic motion as well as the effect of a resistance term on torus are also shown.

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Behavior of a shear layer in a narrow closed channel was observed under periodic excitations. The cross-section of the channel was 15 x 15mm, the characteristic velocity was 12cm/sec, and the thickness of the shear layer wasO (2mm), so that the effects of the side walls were not negligible. Excitation was given at an upstream position on one side of the splitter plate by changing the flow rate periodically with frequency 6-40Hz. Motion of the shear layer depended on the frequency and the amplitude of the excitation. In most cases the layer became wavy and showed a roll-up motion, as has been observed in past studies. But, for a strong excitation with frequency 40 Hz, the layer showed a certain kind of chaotic behavior, in which the layer shifted up and down slowly or tilted irregularly in the spanwise direction. Mechanism of this phenomenon is not clear, but it seems to suggest a new type of chaos in hydrodynamics.

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