Gravity wave

Another approach to measurement of surface tension, density, and viscosity is the analysis of capillary waves or ripples whose properties are governed by surface tension rather than gravity. Space limitations prevent more than a summary presentation here readers are referred to several articles [123,124]. 

Surface waves at an interface between two innniscible fluids involve effects due to gravity (g) and surface tension (a) forces. (In this section, o denotes surface tension and a denotes the stress tensor. The two should not be coiifiised with one another.) In a hydrodynamic approach, the interface is treated as a sharp boundary and the two bulk phases as incompressible. The Navier-Stokes equations for the two bulk phases (balance of macroscopic forces is the mgredient) along with the boundary condition at the interface (surface tension o enters here) are solved for possible hamionic oscillations of the interface of the fomi, exp [-(iu + s)t + i V-.r], where m is the frequency, is the damping coefficient, s tlie 2-d wavevector of the periodic oscillation and. ra 2-d vector parallel to the surface. For a liquid-vapour interface which we consider, away from the critical point, the vapour density is negligible compared to the liquid density and one obtains the hydrodynamic dispersion relation for surface waves + s>tf. The temi gq in the dispersion relation arises from... 

Inertial sensors are useful devices in both science and industry. Higher precision sensors could find practical scientific applications in the areas of general relativity (Chow et ah, 1985), geodesy and geology. Important applications of such devices occur also in the field of navigation, surveying and analysis of earth structures. Matter-wave interferometry has recently shown its potential to be an extremely sensitive probe for inertial forces (Clauser, 1988). First, neutron interferometers have been used to measure the Earth rotation (Colella et ah, 1975) and the acceleration due to gravity (Werner et ah, 1979) in the end of the seventies. In 1991, atom interference techniques have been used in... 

Equation (2-69) is developed by assuming that the fluids are of infinite depth and the force of gravity is not included. The condition for a stable jet is that the wave angular velocity n is real, i.e.,... 

Comparison of the boundaries of the observed flow patterns with the analytical criteria derived by Quandt showed that the bubble, dispersed, and annular flow patterns are subclasses of a pressure gradient-controlled flow. Similarly, flow patterns identified as slug, wave, stratified, and f ailing film are subclasses of a gravity-controlled situation. 

The Leveque-type correlation, Eq. (26), has been used for mass-transfer from a liquid film falling under gravity (110, W13b), where it holds for Reynolds numbers in the laminar range, in spite of the presence of surface waves on the film. The latter caused small local oscillations of the mass-... 

The digestive system of poultry is also basically a tube, beginning at the mouth and ending at the vent (Fig. 13.1). Food is taken in via the mouth and mixed with saliva to lubricate it. The bolus moves down the oesophagus by gravity and a wave-like contraction of the muscles (peristalsis). Then it enters the crop where it is stored if the stomach is full. A certain amount of softening and fermentation may occur here. The crop is situated just outside the entrance of the chest cavity (thoracic inlet) and is an expansion of the oesophagus. 

C. Charbonnel Rotation and Internal Gravity Waves in Low-Mass Stars . In This volume. 

Internal Gravity Waves and Their Mass Dependence... 

These complementary observational constraints indicate that another process participates to the transport of AM in solar-type stars, while MC and turbulence are successful in more massive stars. The two most likely candidates are the large-scale magnetic field which could be present in the radiative zone and the internal gravity waves (hereafter 1GW) which are generated by the external convective zone. As we just explained, the observations suggest that the efficiency of this process is finked to the growth of the convective enveiope. This is a characteristics of 1GW. 

We have now to go one step further and to build stellar evolution models where the transport of angular momentum will be followed self-consistently under the action of meridional circulation, shear turbulence, and internal gravity waves. In this path some important aspects still need to be clarified Can we better describe the excitation mechanisms and evaluate in a more reliable way the quantitative properties of the wave spectra What is the direct contribution of 1GW to the transport of chemicals, especially in the dynamical shear layer produced just below the convective envelope by the wave-mean flow interaction What is the influence of the Coriolis force on IGW How do 1GW interact with a magnetic field Work is in progress in this direction. 

The physical situation is very similar to that of a boat moving on the sea surface, the gravity playing the role of the ponderomotive force in the previous case. The water moves from the immersed volume of the boat towards the stern, where it accumulates in the first crest of a wave produced in the boat... 

But light is also a particle. Some properties of light cannot be explained by the wave-like nature of light, such as the photoelectric effect and blackbody radiation (see Section 9.4), so we also need to think of light comprising particles, i.e. photons. Each photon has a direction as it travels. A photon moves in a straight line, just like a tennis ball would in the absence of gravity, until it interacts in some way (either it reflects or is absorbed). 

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