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Dissertation/Thesis Abstract

Acoustic Attenuation in the Lower Cloud Layer of Venus
by Trahan, Adam J., M.S., University of Louisiana at Lafayette, 2018, 75; 13419931
Abstract (Summary)

Generic predictions for the acoustic wavenumber at low frequencies in the condensational cloud layers of Venus are presented, based on and adapted from the terrestrial model of Baudoin et al. (J. Acoust. Soc. Am. 130. 1142 (2011)). While the general thermodynamics of Earth clouds is well understood, that of Venusian clouds is still a matter of debate. Venus’ clouds are primarily formed of H2O and H2SO4 vapors and aqueous sulfuric acid droplets, the fluxes of which are not fully constrained due to the few in situ observations. Inside the clouds, the Navier-Stokes-Fourier equations of continuum fluid mechanics are used for the gaseous (dry + vapor) and liquid phases of H 2O andH2SO4, combined with equations describing the evaporation/condensation processes; the gaseous phase is treated as an ideal gas and the liquid droplets are considered polydisperse. Thermophysical parameters are interpolated at the ambient conditions pertaining to an altitude of 50 km, a level where balloon platforms (e.g., European Space Agency’s EVE) and manned airships (e.g., NASA’s HAVOC) may be deployed in the future. At low frequencies, the dominant source of absorption is caused by the evaporation/condensation of the liquid phase. At higher frequencies, absorption is dominated by momentum transfers between the wave and the ambient gas and liquid droplets. The intrinsic dispersion is negligible. Sensitivity studies of the attenuation coefficient and the sound speed on the cloud physical parameters is performed, namely, the mean cloud particle size and the cloud density. The attenuation coefficient is sensitive to changes in both mean cloud particle size and cloud density, while the intrinsic dispersion changes negligibly.

Indexing (document details)
Advisor: Petculescu, Andi
Commitee: Petculescu, Andi, Petculescu, Gabriela, Sidorovskaia, Natalia A.
School: University of Louisiana at Lafayette
Department: Physics
School Location: United States -- Louisiana
Source: MAI 58/05M(E), Masters Abstracts International
Subjects: Fluid mechanics, Atmospheric sciences, Acoustics
Keywords: Acoustics, Attenuation, Cloud, Dispersion, Venus
Publication Number: 13419931
ISBN: 978-1-392-04221-2
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