Professor Emeritus James W. Gentry

Ph.D., University of Texas (Austin), 1969

Research Interests

Aerosol Mechanics
Aerosols, particles with diameters between 0.002 um and 100 um, are especially intriguing in that basic physical properties— vapor, pressure, heat of vaporization, chemical equilibria—are strongly influenced by their radius of curvature, that unambiguous on-line measurement techniques are unavailable, and that almost half the natural surface area of the earth is associated with aerosols.

Our research has focused in three general areas—agglomerates, non-spherical aerosols and ultrafine aerosols (those with diameters less than 0.02 um). The principal interest in non-spherical particles and agglomerates is to develop techniques for on-line unambiguous measurement of fiber size and concentration at low concentrations. Such measurements are essential for the characterization of hazardous industrial dusts (i.e., asbestos). Our approach has been to develop instruments based on the electrostatic and aerodynamic properties. In ultrafine aerosols, we are developing instrumentation for their on-line measurements, experiments for checking electrostatic charging theory, and designs for determining the rates of reaction and adsorption in continuous flow reactors.

Our recent studies with aggregates have focused on the use of "fractal" structures to characterize aggregates and experimental studies on thermophoretic deposition in aerosol reactors.

Currently we are we are measuring the thermophoretic desposition (i.e. and electrical charging) of aggregates and the thermophoretic deposition of non-spherical areosols.

A major thrust of our study is the effect of aerosols on environmental quality. These studies focus on the effect of aerosols on visibility and the development of instrumentation and procedures for quantifying the deterioration of visibility with particle concentration and the aerosol size distribution. We are developing algorithms for simulation and analysis of droplet breakage and coalescence using size classes based on Fibonacci series.

Selected Publications

R. J. Han and J. W. Gentry, "Field and Combined Diffusional and Field Charging of Fibrous Aerosols," J. Aerosol Sci. & Tech. 18, pp. 165-179, (1993).

R. J. Han and J. W. Gentry, "Unipolar Diffusional Charging of Fibrous Aerosols - Theory and Experiment," J. Aerosol Sci. 24, pp. 211-226, (1993).

R. J. Han and J. W. Gentry, "Evolution of Charge Distributions of Non-Spherical Particles Undergoing Unipolar Charging," J. Aerosol Sci. 25, pp. 499-508, (1994).

N. Zhang, Y. C. Chang, R. V. Calabrese, and J. W. Gentry, "The Potential Use of Sequences of Fibonacci Series to Simulate Breakage and Agglomeration," Atmospheric Environment 28, pp. 1073-1080, (1994).

J. W. Gentry, J. Gebhart, and G. Scheuch, "A New Method for Estimating Total Efficiencies where Two Mechanisms are Present Simultaneously," J. Aerosol Sci. 25, pp. 315-326, (1994).

J. W. Gentry, J. R. Wu, J. Gebhart, and G. Scheuch, "Numerical Simulation of Porous Plate Classifier," in Proc. International Particle Technology Forum, AIChE, Part III, pp. 379-384, (1994).

Yu-Chen Chang, M. B. Ranade, and J. W. Gentry, "Thermophoretic Deposition in Flow Along an Annular Cross Section : Experiment and Simulation," J. Aerosol Sci. 26, pp. 407-428, (1995).

J. W. Gentry, "The Use of Simulated Fractals in the Analysis of Aggregates," Particulate Sci. & Tech. 13, pp. 23-36, (1995).

J. W. Gentry and S. H. Cheng, "The Effect of Special Classes of Collision Kernels on the Asymptotic Behavior of Size Distributions Undergoing Coagulation," J. Aerosol Science, 27, pp. 519-536, (1996) .

J. W. Gentry and N. C. Liu, "Methods for Predicting Total Size Dependent Particle Collection Efficiencies," in Aerosol Inhalation: Recent Research Frontiers, J.C.M. Marijnissen and L. Gradon, eds., pp. 205-214, (1996).

J.-C. Lin and J. W. Gentry, "Control of Particle Morphology and Homogeneity during Spray Pyrolysis," J. Aerosol Science 27, Supplement 1, pp. 375-376, (1996).

S.-H. Cheng, M. B. Ranade, and J. W. Gentry, "Experimental Design of High Volume Electrostatic Charger," J. Aerosol Science and Technology, pp. 433-446, (1997)