| |
Physical
Acoustics and Optics
Professor
Philip Marston's research activities comprise experimental and theoretical
investigations of physical acoustics, low-gravity fluid mechanics,
and light scattering. Marston's present research in acoustics includes
fundamental aspects of radiation and scattering of sound from elastic
objects in water and investigations of novel processes for the interaction
of sound with sound in modified fluids. The research on scattering
involves the use of ray methods to describe Lamb and Rayleigh wave
contributions to radiation and scattering from complicated objects.
An indoor water tank facility (containing tanks having capacities
of 6500 and 3000 gallons) makes a wide range of acoustic measurements
possible for testing theoretical predictions. In other research,
a nonlinear process under investigation reveals that (in comparison
with water) a modified liquid exhibits a greatly enhanced interaction
of sound with sound. Other acoustics research involves the radiation
pressure of high-amplitude sound and its applications to bubble
and droplet dynamics and to the dynamics of fluids in low gravity.
Marston was a co-principal investigator of a related bubble dynamics
experiment flown on the USML-1 space shuttle flight in 1992 and
related investigations of the responses of fluids to radiation pressure
are ongoing. In other research on scattering, catastrophe theory
was used to analyze novel foci discovered in optical scattering
patterns from spheroids. These "diffraction catastrophes"
were subsequently applied to the inverse problem of determining
properties of the scatterer from the scattering data. Marston's
work in optics also includes a systematic study of diffraction anomalies
in the scattering from bubbles in water. Structures in the scattering
patterns associated with a critical angle and with enhanced backscattering
(or the "glory") are examples of such anomalies. The optical
and acoustical research efforts are complementary and light scattering
research has been useful for insight into certain complicated acoustical
scattering situations such as those producing acoustical diffraction
catastrophes. Marston is a Fellow of the Acoustical Society of America.
|
|
|
|
|
|
