Laboratory studies on the surface drift current induced by wind and swell

Abstract

Systematic measurements of the surface drift current, the wind profile over the water surface and the wave spectra have been made for (i) pure wind-waves, (ii) a coexisting system of wind-waves and swell propagating against the wind, and (iii) a coexisting system of wind-waves and swell propagating in the direction of the wind. The surface drift current is gradually intensified by the swell propagating against the wind when the swell steepness increases. The maximum increase of the surface drift velocity caused by the opposing swell is about 46 % of the surface drift velocity for pure wind-waves at the same wind speed. Such a phenomenon was not observed when the swell was propagating in the direction of the wind.

Excitation of transverse magnetic tube waves in stellar convection zones

“…It must be also pointed out that the term ρ e ∂v x /∂t describes the apparent increase of inertia of the tube resulting from the backreaction of the external fluid on the oscillating tube (Basset 1961;Spruit 1981). More recently, some authors (Choudhuri 1990;Cheng 1992;Fan et al 1994;Moreno-Insertis et al 1996;Osin et al 1999) have criticized the treatment of this term by Spruit and suggested several modifications. The criticism and the resulting modifications have been extensively discussed by Osin et al, who also proposed their own modification of the equation of motion.…”

A Viscoelastic Theory of Turbulent Fluid Permeated with Fibril Magnetic Fields

“…Nonlinear, dynamical equations for the evolution of a thin flux tube were proposed by Spruit (1981) and have been refined and extended by subsequent authors (Choudhuri 1990;Cheng 1992;Moreno-Insertis & Emonet 1996). These models are most frequently used to study the buoyant rise of an active region flux tube through the solar CZ (see, e.g., Fisher et al 2000 and references therein).…”

Interaction and growth of low frequency and high frequency wind waves

“…However, in the spectra published by Cheng and Mitsuyasu (1992), also for LF waves opposing wind, enhancement of HF waves was less obvious than what was displayed by Mitsuyasu and Yoshida (1991), and much less clear than the magnitude of suppression for LF waves following the wind reported in other studies (e.g. Mitsuyasu, 1966).…”

“…The spectral peaks of HF waves in Figure 2.14 did not change significantly with opposing LF waves, but energy increased at HF wave frequencies lower than the peak, as seen in Figure 2.14. Cheng & Mitsuyasu (1992) described this as the HF spectrum becoming wider, and it can be seen that this entails a downshift in average HF frequency. It must be kept in mind that any downshift in average HF wave frequency, though not increasing the energy density, will still increase the magnitude of energy flux passing through any given space.…”

“…Studies of the interaction between HF waves and LF waves opposing the wind are fewer than those for LF waves following the wind, with the majority of relevant observations seemingly originating from the one research group, although reported in multiple publications (Mitsuyasu and Yoshida, 1989;Mitsuyasu and Yoshida, 1991;Cheng and Mitsuyasu, 1992;Mitsuyasu and Yoshida, 2005). These experiments were performed using distributed wave gauges throughout an effective fetch of ca.…”