Tidal Displacements Research Articles

Tidal Deformation of the Moon.

Tides on the surface of the Moon are investigated. The tidal potential, gravity and displacements on the surface of the Moon are expanded in harmonics depending on general forms of the lunar motion, which would accept the orbital evolution. These are expressed in numerical formulas more exactly for uses in correction for precise determination of the lunar motions and for possible observations of the tides of the Moon. Love numbers are computed for some expected models of the lunar interior.

Numerical simulation of time-dependent heat transfer in oscillating pipe flow

The problem of Enhanced Axial Heat Transfer (EAHT) in oscillatory pipe flow has been numerically studied. Time-dependent velocity and temperature profiles and Lagrangian and tidal displacements at various Wormersley numbers are obtained. The enhanced axial heat flux for different tidal displacements is calculated. The wall thickness effect in EAHT is also studied, and the optimum wall thickness is shown to be about 20% of the pipe radius in the test case studied. In addition, the tuning effect in axial heat flow is examined, the results indicating good agreement with analytic predictions. The numerical studies show that EAHT can be a very effective tool for those problems in which a large amount of heat must be transported without an accompanying convective mass exchange.

Enhanced heat conduction in oscillating viscous flows within parallel-plate channels

The hydrodynamics of enhanced longitudinal heat transfer through a sinusoidally oscillating viscous fluid in an array of parallel-plate channels with conducting sidewalls is examined analytically. Results show that for fixed frequency the corresponding effective thermal diffusivity reaches a maximum when the product of the Prandtl number and the square of the Womersley number is approximately equal to α2Pr = π Under such tuned conditions the axial heat transfer achievable is considerable and can exceed that possible with heat pipes by several orders of magnitude. The heat flux between different temperature reservoirs connecting the parallel-plate-channel configuration is shown, under tuned conditions, to be proportional to the first power of both the axial temperature gradient and the flow oscillation frequency and to the square of the tidal displacements. A large value for the fluid density and specific heat is also found to be beneficial when large heat-transfer rates are desired. The process discussed involves no net convection and hence achieves large heat-transfer rates (in excess of 106 W/cm2) without a corresponding net convective mass transfer. A discussion of the physical origin for this new heat-transfer process is given and suggestions for applications are presented.

Enhanced dispersion in oscillatory flows

Measurements of the dispersion coefficient in oscillating pipe flows for a wide range of Womersley numbers, tidal displacements, and tube radii are presented. The results are shown to be in good agreement with those of a recent laminar dispersion theory for oscillatory flows.

A quasi‐geometric method for investigating tidal displacements of the Earth's surface using laser ranging to Geos 3

An analysis of NASA laser ranging data from three stations located at Goddard Space Flight Center, Greenbelt, Maryland, Grand Turk Island, and Bermuda, respectively, was carried out in an attempt to measure the geometric earth tide. A ‘quasi‐geometric’ method was employed that reduces the dependence on unmodelled satellite dynamics to a knowledge of only the radial position of the satellite by considering two‐station simultaneous ranging at the precise time that the satellite passes through the plane defined by the two stations and the center of mass of the earth. Using this method, a good approximation to the theoretical Love number h2 was obtained from five passes over the Geos 3 calibration area when the geocentric distance to the satellite is adjusted by an amount, the same for each pass, which yields the least sum of the squares of the errors in the stations' geocentric distances and their angular separations.