Российский фонд
фундаментальных
исследований

Физический факультет
МГУ им. М.В.Ломоносова
 

08.05 Распространение и рассеяние на турбулентности и на неоднородных течениях

 

Bakushinsky B., Leonov A.S. «Modeling the Solution of the Acoustic Inverse Problem of Scattering for a Three-Dimensional Nonstationary Medium» Acoustical Physics, 70, № 1, с. 153-164 (2024)

The inverse problem of acoustic sounding of a three-dimensional nonstationary medium is considered, based on the Cauchy problem for the wave equation with a sound speed coefficient depending on the spatial coordinates and time. The data in the inverse problem are measurements of time-dependent acoustic pressure in some spatial domain. Using these data, it is necessary to determine the positions of local acoustic inhomogeneities (spatial sound speed distributions), which change over time. A special idealized sounding model is used, in which, in particular, it is assumed that the spatial sound speed distribution changes little in the interval between source time pulses. With such a model, the inverse problem is reduced to solving three-dimensional Fredholm linear integral equations for each sounding time interval. Using these solutions, the spatial sound speed distributions are calculated in each sounding time interval. When a special (plane-layer) geometric scheme for the location of the observation and sounding domains is included in the sounding scheme, the inverse problem can be reduced to solving systems of one-dimensional linear Fredholm integral equations, which are solved by well-known methods for regularizing ill-posed problems. This makes it possible to solve the three-dimensional inverse problem of determining the nonstationary sound speed distribution in the sounded medium on a personal computer of average performance for fairly detailed spatial grids in a few minutes. The efficiency of the corresponding algorithm for solving a three-dimensional nonstationary inverse sounding problem in the case of moving local acoustic inhomogeneities is illustrated by solving a number of model problems.

Acoustical Physics, 70, № 1, с. 153-164 (2024) | Рубрики: 04.01 07.16 08.05 12.04

 

Теодорович Э.В. «Спектральные характеристики турбулентности в широком диапазоне волновых чисел» 9-я Международная конференция – школа молодых ученых «Волны и вихри в сложных средах». Москва, 05–07 декабря 2018 г., с. 148-150 (2018)

9-я Международная конференция – школа молодых ученых «Волны и вихри в сложных средах». Москва, 05–07 декабря 2018 г., с. 148-150 (2018) | Рубрика: 08.05

 

Bychkov P., Faranosov G.A. «Hot-Wire-Based Estimation of Pressure Fluctuations in the Near Field of a Jet in the Presence of a Coflow» Acoustical Physics, 70, № 1, с. 116-129 (2024)

It is shown that the velocity fluctuation spectra measured using a hot wire in the potential flow region of the near field of a turbulent jet with a coflow can be converted into pressure fluctuation spectra. The proposed conversion method is based on the fact that the structure of instability waves, which make a decisive contribution to jet near-field fluctuations, resembles homogeneous one-dimensional waves, which makes it possible to locally link pressure fluctuations and the fluctuations of the streamwise velocity component measured by a hot wire.

Acoustical Physics, 70, № 1, с. 116-129 (2024) | Рубрики: 08.05 08.13 10.01