Bayard D. Clarkson Distinguished Professor
Mechanical & Aeronautical Eng
PO Box 5725
Potsdam, NY 13699-5725
B.Tech, Indian Institute of Technology
M.S., University of Delaware
Ph. D., University of Minnesota
Professor Dhaniyala's current research interests are in the fields of Nano-Aerosol, Aerosol and Cloud Physics, and Aerosol Instrumentation.
The numerical and theoretical research concerns improved, integrated modeling of fluid flow, particle transport, and aerosol thermodynamics under conditions of non-equilibrium. This research is of importance in short time-scale aerosol events and for high-speed particle analysis. The modeling techniques are also used in the development of new aerosol instruments optimized for accurate, fast response combined with ease of construction.
The experimental research has concentrated on the development of next generation of instruments for real-time characterization of nanoparticles and large particles. New designs for particle/gas sampling from high-speed aircraft for analysis of cloud systems are also being developed.
- NSF CAREER Award, 2006
- Teaching Excellence, Clarkson University, Spring 2005
- Maurice Simpson Technical Editors Award for contamination control from the Institute of Environmental Sciences and Technology, 2000
- Rosemount Instrumentation Award for best instrument design from Rosemount Co., 1997-98
- Fellowship, North Central Chapter of the American Filtration and Separation Society, 1997-98
Current Research Projects
- New Techniques for Aerosol-Cloud Analysis
Aerosol influence on global climate is potentially as important as that of greenhouse gases, but our lack of detailed knowledge on the mechanisms of aerosol-cloud processes results in considerable uncertainty in global climate model (GCM) predictions. In particular, the contribution of aerosol indirect effect, associated with the complicated interaction of aerosol particles with the formation and precipitation efficiency of liquid-water, ice, and mixed-phase clouds, to the radiative forcing budget is largely uncertain. In-situ studies of atmospheric aerosol-cloud processes and improved microphysical modeling are required to better model and predict the role of aerosols particles in global climate. In this project, new techniques are being developed for accurate sampling and fast analysis of aerosol and cloud droplets from high-speed aircraft. In addition, optimized designs of gas-sampling inlets are also being developed. (Funded by NSF and NASA).
- Nanoparticle Characterization
Nanoparticles in the environment are produced as a result of both anthropogenic activities (e.g., combustion) and natural processes (e.g., biogenic). In the urban environments, nanoparticles generally dominate the aerosol number and surface distributions, but their properties are seen to have large spatial and temporal inhomogeneity. For effective characterization of nanoparticles, real-time measurements of physical and chemical properties are required. In this project, electrical mobility techniques are being used for the development of new, compact instruments for real-time nanoparticle sizing and compositional characterization. (Funded by NSF and NYSERDA).
- Near Real-Time Aerosol Studies
The deposition of pollutants associated with PM are significant inputs to many ecosystems. There is an urgent need for techniques that can measure PM and pollutants associated with PM at short enough time scales that sources of these particles can be characterized and mechanistic models of their chemistry and fate developed. Since health effects and deposition are dependent on particle size, these techniques should also be able to separate the PM by size before they are characterized. To avoid sampling artifacts, the particles must be separated from the gas stream before collection. Research for this project involves: study of large particle transport characteristics, theoretical , numerical, and experimental study of ground-based counterflow virtual impactor; and study of species desorbtion and transport characteristics as a function of gas flow and temperature. (Funded by NSF).
- Numerical modeling of near-wall effects
An ideal passive sampler for gas-phase species such as PAHs, PCBs, etc would have a high sampling rate that is largely independent of ambient wind-conditions. The development of such a sampler requires an understanding of the interaction of gas-phase species with wall surfaces for a range of flow conditions. Numerical simulations of this system are complicated by the availability of different parametric turbulent models in commercial CFD codes that result in varying fluid flow solutions for conditions consistent with those in passive samplers. In this study, numerical and experimental fluid flow and species-transport modeling are being performed to determine the modeling accuracies of different turbulent schemes, and to design an optimized passive gas sampler (Funded by Great Lakes Consortium).
Rodrigue J., Ranjan M., Hopke P.K., and Dhaniyala S., Comparison Electrical Mobility Spectrometers: TSI SMPS 3936 and MSP WPS XP 1000, Accepted for Publication in Aerosol Science and Technology, December
Eddy P.R., Natarajan A., Dhaniyala S., Subisokinetic Sampling Characteristics Aircraft Inlets: A New CFD-based Correlation Considering Inlet Geometries, Accepted for publication in Journal of Aerosol Science, October 2006.
Thomas, JJ, Holsen TM, Dhaniyala S, Computational fluid dynamics samplers, Environmental Pollution, 144:384-392, 2006.
Thomas, JJ, Holsen TM, Dhaniyala S, Computational fluid dynamics modeling of two passive samplers, Environmental Pollution, Accepted for publication, 2005.
Dhaniyala, S; Wennberg, PO; Flagan, RC; Fahey, DW; Northway, MJ; Gao, RS; Bui, TP. 2004. Stratospheric aerosol sampling: Effect of a blunt-body housing on inlet sampling characteristics. Aerosol Science and Technology, 38 (11): 1080-1090.
Popp, PJ; Gao, RS; Marcy, TP; Fahey, DW; Hudson, PK; Thompson, TL; Karcher, B; Ridley, BA; Weinheimer, AJ; Knapp, DJ; Montzka, DD; Baumgardner, D; Garrett, TJ; Weinstock, EM; Smith, JB; Sayres, DS; Pittman, JV; Dhaniyala, S; Bui, TP; Mahoney, MJ. 2004. Nitric acid uptake on subtropical cirrus cloud particles (vol 109, art no D06302, 2004). Journal of Geophysical Research-Atmospheres, 109 (D8): art. no.-D08306.
Popp, PJ; Gao, RS; Marcy, TP; Fahey, DW; Hudson, PK; Thompson, TL; Karcher, B; Ridley, BA; Weinheimer, AJ; Knapp, DJ; Montzka, DD; Baumgardner, D; Garrett, TJ; Weinstock, EM; Smith, JB; Sayres, DS; Pittman, JV; Dhaniyala, S; Bui, TP; Mahoney, MJ. 2004. Nitric acid uptake on subtropical cirrus cloud particles. Journal of Geophysical Research-Atmospheres, 109 (D6): art. no.-D06302.
McKinney, KA; Wennberg, PO; Dhaniyala, S; Fahey, DW; Northway, MJ; Kunzi, KF; Kleinbohl, A; Sinnhuber, M; Kullmann, H; Bremer, H; Mahoney, MJ; Bui, TP. 2004. Trajectory studies of large HNO3-containing PSC particles in the Arctic: Evidence for the role of NAT. Geophysical Research Letters, 31 (5): art. no.-L05110.
Dhaniyala, S; Flagan, RC; McKinney, KA; Wennberg, PO. 2003. Novel aerosol/gas inlet for aircraft-based measurements. Aerosol Science and Technology, 37 (10): 828-840.
Hanisco, TF; Smith, JB; Stimpfle, RM; Wilmouth, DM; Perkins, KK; Spackman, JR; Anderson, JG; Baumgardner, D; Gandrud, B; Webster, CR; Dhaniyala, S; McKinney, KA; Bui, TP. 2002. Quantifying the rate of heterogeneous processing in the Arctic polar vortex with in situ observations of OH. Journal of Geophysical Research-Atmospheres 107 (D20): art. no.-8278.
Northway, MJ; Gao, RS; Popp, PJ; Holecek, JC; Fahey, DW; Carslaw, KS; Tolbert, MA; Lait, LR; Dhaniyala, S; Flagan, RC; Wennberg, PO; Mahoney, MJ; Herman, RL; Toon, GC; Bui, TP. 2002. An analysis of large HNO3-containing particles sampled in the Arctic stratosphere during the winter of 1999/2000. Journal of Geophysical Research-Atmospheres, 107 (D20): art. no.-8298.
Dhaniyala, S; Mckinney, KA; Wennberg, PO. 2002. Lee-wave clouds and denitrification of the polar stratosphere. Geophysical Research Letters, 29 (9): art. no.-1322.
Fahey, DW; Gao, RS; Carslaw, KS; Kettleborough, J; Popp, PJ; Northway, MJ; Holecek, JC; Ciciora, SC; McLaughlin, RJ; Thompson, TL; Winkler, RH; Baumgardner, DG; Gandrud, B; Wennberg, PO; Dhaniyala, S; McKinney, K; Peter, T; Salawitch, RJ; Bui, TP; Elkins, JW; Webster, CR; Atlas, EL; Jost, H; Wilson, JC; Herman, RL; Kleinbohl, A; von Konig, M. 2001. The detection of large HNO3-containing particles in the winter arctic stratosphere. Science, 291 (5506): 1026-1031.