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.
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).
- P. Dubey and S. Dhaniiyala, "A new multiscale expectation-maximization algorithm for accurate SMPS data inversion," Aerosol Science and Technology, accepted (August 2012).
- M. He and S. Dhaniyala, "Vertical and Horizontal Concentration Distributions of Ultrafine Particles near a Highway," Atmospheric Environment, 46, 225-236 (2012).
- S. Dhaniiyala, P. Dubey and K. Balakrishnan, "Air quality in rural India: Role of ultrafine particles from cookstoves," Environmental Manager (Invited Article), Magazine of American Waste and Air Association (August 14-18, 2011).
- M. He and S. Dhaniyala, "Evelopment of a Dispersion Model for Traffic Produced Turbulence in a Two-Way Traffic Scenario," Environmental Fluid Mechanics, Volume 11, Number 6, 627-640, DOI: 10.1007/s10652-011-9215-2 (2011).
- P. Dubey and S. Dhaniyala, "A new approach to calculate diffusional transfer functoins of scanning DMAs, Aerosol Science and Tejchnolgoy, 45:8, 1031-1040 (2011).
- M. Ranjan and S. Dhaniyala, "A novel electrical-mobility-based instrument for total number concentration measurements of ultrafine particles," Journal of Aerosol Science, doi: 10.1016/j.jaerosci.2009.01.007 (2009).
- R.Q. Iannone, S. Kassi, Hans-Jürg Jost, M. Chenevier, D. Romanini, H.A.J. Meijer, S. Dhaniyala, M. Snels and E.R.T. Kerstel, "Development and airborne operation of a compact water isotope ratio infrared spectrometer," Isotopes in Environmental and Health Studies,99999:1, DOI: 10.1080/10256010903172715 (2009).
- M. Ranjan and S. Dhaniyala, "A novel electrical-mobility-based instrument for total number concentration measurements of ultrafine particles," Journal of Aerosol Science, 2009, doi: 10.1016/j.jaerosci.2009.01.007 (2009) .
- P. Dubey and S. Dhaniyala, "Analysis of scanning DMA transfer functions," Aerosol Science and Technology, 42:7, 544-555 (2008).
- M. Ranjan and S. Dhaniyala, "A new miniature electrical aerosol spectrometer: Experimental characterization," Journal of Aerosol Science, doi: 10.1016/j.jaerosci.2008.04.005 (2008).
- S.R. Lee, S. Dhaniyala and T.H. Holsen, "Design and Development of Novel Large Particle Inlet for PM larger than 10 mm (PM>10)," Aerosol Science and Technology, 42:2, 140-151 (Feb 2008).
- H. Meilu, S. Dhaniyala and P. Marzocca, A New High Performance Battery-Operated Electrometer, Review of Scientific Instrumentation 78, 105103 (October 2007).
- M. Ranjan and S. Dhaniyala, "Theory and design of a new miniature electrical-mobility aerosol spectrometer," Journal of Aerosol Science, doi:10.1016/j.jaerosci.2007.07.005 (2007).
- D.K. Song and S. Dhaniyala, "Nanoparticle cross-flow differential mobility analyzer (NCDMA): Theory and design," Journal of Aerosol Science, 10.1016/j.jaerosci.2007.07.004 (2007).
- J. Rodrigue, M. Ranjan, P.K. Hopke and S. Dhaniyala, "Comparison of Two Commercial Scanning Electrical Mobility Spectrometers: TSI SMPS 3936 and MSP WPS XP 1000," Aerosol Science and Technology, 41:4, 360 - 368 (2007).
- D.K. Song and S. Dhaniyala, "Change in distributions of particle positions by Brownian diffusion in a non-uniform external field," Journal of Aerosol Science (2007), doi: 10.1016/j.jaerosci.2007.01.006, (2007).
- P.R. Eddy, A. Natarajan and S. Dhaniyala, "Subisokinetic Sampling Characteristics of High Speed Aircraft Inlets: A New CFD-based Correlation Considering Inlet Geometries," Journal of Aerosol Science 37 (12): 1853-1870 (Dec 2006).
- J.J. Thomas, T.M. Holsen and S. Dhaniyala, Computational fluid dynamics modeling of two passive samplers, Environmental Pollution, 144:384-392 (2006).
- J.J. Thomas, T.M. Holsen and S. Dhaniyala, "Computational fluid dynamics modeling of two passive samplers," Environmental Pollution, Accepted for publication (2005).
- S. Dhaniyala, P.O. Wennberg, R.C. Flagan, D.W. Fahey,M.J. Northway, R.S. Gao and T.P. Bui, "Stratospheric aerosol sampling: Effect of a blunt-body housing on inlet sampling characteristics," Aerosol Science and Technology, 38 (11): 1080-1090 (2004).
- P.J. Popp, R.S. Gao, T.P. Marcy, D.W. Fahey, P.K. Hudson, T.L. Thompson, B. Karcher, B.A. Ridley, A.J. Weinheimer, D.J. Knapp, D.D. Montzka, D. Baumgardner, T.J. Garrett, E.M. Weinstock, J.B. Smith, D.S. Sayres, J.V. Pittman, S. Dhaniyala, T.P. Bui, and M.J. Mahoney, "Nitric acid uptake on subtropical cirrus cloud particles," (vol 109, art no D06302, 2004), Journal of Geophysical Research-Atmospheres, 109 (D8): art. no.-D08306 (2004).
- P.J. Popp, R.S. Gao, T.P. Marcy, D.W. Fahey, P.K. Hudson, T.L. Thompson, B. Karcher, B.A. Ridley, A.J. Weinheimer, D.J. Knapp, D.D. Montzka, D. Baumgardner, T.J. Garrett, E.M. Weinstock, J.B. Smith, D.S. Sayres, J.V. Pittman, S. Dhaniyala, T.P. Bui, and M.J. Mahoney, "Nitric acid uptake on subtropical cirrus cloud particles. Journal of Geophysical Research-Atmospheres," 109 (D6): art. no.-D06302 (2004).
- K.A. McKinney, P.O. Wennberg, S. Dhaniyala, D.W. Fahey, M.J. Northway, K.F. Kunzi, A. Kleinbohl, M. Sinnhuber, H. Kullmann, H. Bremer, M.J. Mahoney and T.P. Bui, "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 (2004).
- S. Dhaniyala, R.C. Flagan, K.A. McKinney and P.O. Wennberg, "Novel aerosol/gas inlet for aircraft-based measurements," Aerosol Science and Technology, 37 (10): 828-840 (2003).
- T.F. Hanisco, J.B. Smith, R.M. Stimpfle, D.M. Wilmouth, K.K. Perkins, J.R. Spackman, J.G. Anderson, D. Baumgardner, B. Gandrud, C.R. Webster, S. Dhaniyala, K.A. McKinney and T.P. Bui, 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 (2002).
- M.J. Northway, R.S. Gao, P.J. Popp, J.C. Holecek, D.W. Fahey, K.S. Carslaw, M.A. Tolbert, L.R. Lait, S. Dhaniyala, R.C. Flagan, P.O. Wennberg, M.J. Mahoney, R.L. Herman, G.C. Toon and T.P. Bui, "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 (2002).
- S. Dhaniyala, K.A. Mckinney, P.O. Wennberg, "Lee-wave clouds and denitrification of the polar stratosphere," Geophysical Research Letters, 29 (9): art. no.-1322 (2002).
- D.W. Fahey, R.S. Gao, K.S. Carslaw, J. Kettleborough, P.J. Popp, M.J. Northway, J.C. Holecek, S.C. Ciciora, R.J. McLaughlin, T.L. Thompson, R.H. Winkler, D.G. Baumgardner, B. Gandrud, P.O. Wennberg, S. Dhaniyala, K. McKinney, T. Peter, R.J. Salawitch, T.P. Bui, J.W. Elkins, C.R. Webster, E.L. Atlas, H. Jost, J.C. Wilson, R.L. Herman, A. Kleinbohl and M. von Konig, "The detection of large HNO3-containing particles in the winter arctic stratosphere," Science, 291 (5506): 1026-1031 (2001).