Collaborations

Here is a list of some of my collaborators and a brief description of the projects we are working on.

NASA

I am working with Dr. Larry F. Bliven of NASA's Wallops Flight Facility (part of Goddard Space Flight Center ). Dr. Bliven is the developer of NASA's Rain Imaging System (RIS) which is a disdrometer capable of obtaining size and shape distributions of raindrops via direct optical imaging in real time. Through this collaboration, we are utilizing the RIS to investigate how drop size and shape distributions evolve during rain storms. We are also investigating the way that storm type (e.g. convective versus stratiform) affects these distributions.

Rensselaer Polytechnic Institute

With the research group of Professor G. M. Korenowski, I am investigating the interrelationship between capillary waves and surfactants. We are utilizing second harmonic generation (SHG) to measure the concentration field on a water surface populated by a standing field of capillary waves. A circular, standing, capillary wave field is generated in a small, round tank. The wavelengths are ~3 mm. The following is a preliminary image of a small portion of such a wave field.

Figure 1 (J. Kelley)

The curved waves are visible in this preliminary image. The darker regions indicate areas of higher surfactant concentration. The pink regions are low concentration regions,or regions where the signal falls below the noise floor. Although not apparent in the image, the concentration of the surfactant decreases as one moves from the center of the wave field (image center), radially outward. This is due to the decay in wave amplitude inherent in a circular wave field of this type.

University of California, Berkeley

The development of a optical diagnostic method for characterizing surfactant monolayers is being performed in collaboration with Professor A. J. Szeri . In this project, we are seeking to measure the elasticity of a surfactant monolayer in a non- invasive fashion. Using laser diagnostics, the slope of a circular capillary wave field is measured along a radius. From these measurements, values for the wavelength, decay coefficient, and elasticity are obtained While such measurements have been conducted in rectangular facilities, very little work of this type has been performed in circular facilities, where several advantages provide for a more accurate measurement of elasticity.

The following is a plot of the amplitude of the wave slope as a function of radial position, for the wave field. The water surface is coated with a monolayer of stearic acid.

Figure 2

United States Naval Academy

In this project, we are investigating the role which surfactants play in evaporative convection. Specifically, the effect which surfactants have on the temperature field and subsurface velocity field, of a body of water undergoing evaporation is sought. This work is being done in collaboration with Professor K. A. Flack of the United States Naval Academy, and Dr. G. B. Smith of NRL. Details of this project can be found in the "Research" portion of this web page, and can be accessed directly by clicking here. Additional research on infrared imagery of the free surface due to Dr. Smith can be found by clicking here

Briefly, we have used infrared imagery to measure the temperature field of a water surface which is undergoing evaporation. We have demonstrated that the presence of a surfactant monolayer reduces the amount of small scale structure in this temperature field, even when the heat flux is unchanged. This is illustrated in the two images below, which show the temperature field of a clean water surface on the left and a water surface coated with a surfactant monolayer on the right.

clean surface (ir) surfactant covered surface (ir)

E-Mail: jrsaylor@ces.clemson.edu

Last Updated December 6, 2006.