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[en] The change in the orbital period of the system WASP-46 due to quasi-static and dynamical tidal interactions is investigated. Various dissipation mechanisms are studied. In the case of quasi-static tides, dissipation is assumed to occur due to turbulent viscosity, while in the case of dynamical tides, two limiting cases are considered: the regime of moderately large dissipation and the regime of weak dissipation due to radiative viscosity. The change in the orbital period of WASP-46 is calculated and compared with observations. The regime of moderately large dissipation is shown to describe best the observations.
[en] Recently, there has been a great interest in the tidal contribution to vertical mixing in the ocean. In models, vertical mixing is estimated using parameterization of the sub-grid scale processes. Estimates of the vertical mixing varied widely depending on which vertical mixing parameterization was used. This study investigated the performance of ten different vertical mixing parameterizations in a terrain-following ocean model when simulating internal tides. The vertical mixing parameterization was found to have minor effects on the velocity fields at the tidal frequencies, but large effects on the estimates of vertical diffusivity of temperature. Although there was no definitive best performer for the vertical mixing parameterization, several parameterizations were eliminated based on comparison of the vertical diffusivity estimates with observations. The best performers were the new generic coefficients for the generic length scale schemes and Mellor-Yamada's 2.5 level closure scheme.
[en] The tidal force effects of a spherical galaxy passing head-on through a disk galaxy have been studied for various orientations of the disk galaxy with respect to the direction of relative motion of the two galaxis. The density distribution of the spherical galaxy is taken to be that of a polytrope of index n = 4 and that of the disk galaxy is taken to be, sigma(r) = sigmasub(c)e-4sup(r)sup(/)sup(R), where sigmasub(c) is the central density and R the radius of the disk. It is found that the disruptive effects due to the tidal force are minimum when the plane of the disk lies along the direction of relative motion, but are maximum when the plane of the disk is slightly inclined to this direction (about 150). The tidal force effects at the median radius have also been computed. The tidal force effects are much higher in the interior region of the disk. (orig.)
[en] The mechanism of sediment transport in the shallow water of lagoons is discussed. If capable to lift up the sediments, the tidal currents are shown to tend to fill up the lagoon. The main mechanism for sediment suspension is found in wind waves, caused by intermittent strong winds. Tidal current acts then as a carrier. This argument is discussed both theoretically and on the basis of experimental data. (author)