doi:
UDK: 534.286

FORMATION OF AN ACOUSTIC BOUNDARY LAYER NEAR THE SURFACE OF A LIQUID – SOLID ABSOLUTELY THERMALLY CONDUCTIVE BODY

Григорьева Н. С., Легуша Ф. Ф., Клюбина К. А.
Article language: английский

Annotation

The theoretical descriptions of the physical processes of excitation of inhomogeneous viscous and thermal waves obtained by G. Kirchoff and L.D. Landau are compared. Inhomogeneous waves are excited in a viscous and heat-conducting medium in contact with a flat surface of a solid absolutely heat-conducting body when interacting with the surface of a body of a flat traveling sound wave. It is shown that the analyzed solutions of the problems are physically justified, independent and complementary to each other. On this basis, it can be argued that the formation of an acoustic boundary layer that occurs in a liquid medium near a sound-reflecting surface, viscous and heat waves are excited synchronously in pairs. At the same time, in each pair, inhomogeneous waves propagate inside the acoustic boundary layer towards each other. Inhomogeneous waves originate on parallel surfaces that limit the volume of the acoustic boundary layer on both sides. It is also established that as a result of the transformation of heat waves, two additional inhomogeneous one-dimensional longitudinal waves appear in the boundary layer. This effect was predicted by G. Kirchoff in 1868 year. The equations of motion of inhomogeneous waves existing in the acoustic boundary layer are obtained. The analysis of the physical properties of viscous and thermal waves is carried out. The expressions presented in the paper allow further numerical evaluation of energy dissipation in the acoustic boundary layer and to evaluate the effect of dissipative processes on the parameters of a sound wave reflected from the surface of a solid absolutely heat-conducting body. In practice, the results obtained in the article can be used, for example, in the tasks of combating air noise in ship premises. In particular, these results allow us to calculate the proportion of acoustic field energy absorbed by surfaces that limit the internal volume of the room. Keywords: sound wave, flat solid surface, absolutely heat-conducting body, viscous wave, heat wave, inhomogeneous wave, acoustic boundary layer, attenuation, energy dissipation

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