Andi Petculescu, Department of Physics, University of Louisiana at Lafayette, Lafayette, LA 70504-4210, USA
Molecular acoustics studies the effects of molecular relaxation on sound propagation in fluids. The field was effectively started by Lev Landau and Edward Teller in 1936 in a paper describing the relationship between intermolecular energy transfer and intrinsic absorption and dispersion of sound, via relaxational processes.
In this presentation I will review the basics of molecular acoustics and present a first-principles model predicting the complex acoustic wavenumber in polyatomic gases. Then I will discuss applications in two fields: quantitative sonic gas analysis and sound propagation in planetary atmospheres. It has long been a ``mantra'' of acoustic gas sensing that one can only use acoustic methods to measure the mean molecular weight of a gas mixture. We have shown that, if one measures the acoustic absorption beside sound speed, one can perform quantitative sensing i.e. infer the nature of the molecules. On the planetary science front, most planetary exploration missions have been 'deaf,' with a few notable exceptions. However, acoustics offers many benefits to understanding alien environments. I will present our latest results of predicting sound propagation on Titan and, time-permitting, preliminary data for Mars and Venus.
Site web du groupe du Prof. Petculescu's
Cette conférence est présentée par le RQMP Versant Nord du Département de physique de l'Université de Montréal et le Département de génie physique de Polytechnique Montréal.
