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  • Pathak, B., Basu, S. and Kumar, R.,. “Dynamics of Droplet Break-Up” in Droplet and Sprays: Application for Combustion and Propulsion, Springer Nature Singapore (2018).
  • R. Kumar, “Two-Phase flow microstructures in thin geometries: Multi-field modeling,” Ch. 5 in Heat Transfer and Fluid Flow in Microstructures and Nanostructures, Eds. Faghri and Sunden, WIT Press, pp. 173-224, 2004. 

  • T. Li, A. Kar and R. Kumar, “Marangoni circulation by UV light modulation on sessile drop for particle agglomeration,” J. Fluid Mech. 873, pp. 72-88 (2019).
  • Castillo-Orozco, E., Kumar, R., & Kar, A., “Laser-induced subwavelength structures by microdroplet superlens,” Opt. Express 27, 8130-8142 (2019).
  • Castillo-Orozco, E., Kumar, R. & Kar, A., “Laser electrospray printing of nanoparticles on flexible and rigid substrates,” J. Laser Appl. 31, 022015 (2019).
  • M. Nooranidoost, M. Haghshenas, M. Muradoglu, R. Kumar, “Cell encapsulation modes in a flow‑focusing microchannel: effects of shell fluid viscosity,” Microfluidics and Nanofluidics, 23:31 (2019).
  • J. Wilson, M. Haghshenas and R. Kumar, “Phase change mechanism for evaporation in porous media using volume of fluid: Implicit formulation of interfacial temperature,” Int. Comm. Heat Mass Transfer, 103, pp. 90-99 (2019).
  • M. Nooranidoost and R. Kumar, “Geometry Effects of Axisymmetric Flow-Focusing Microchannels for Single Cell Encapsulation,” Materials, 12(17), 2811, (2019).
  • T. Li, A. Kar and R. Kumar, “Concentration distribution of photosensitive liquid in a droplet under UV light,” J. Fluids Eng., https://doi.org/10.1115/1.4044442 (2019).
  • K. Hanthanan Arachchilage, M. Haghshenas, S. Park, L. Zhou, Y. Sohn, B. McWilliams, K. Cho, R. Kumar, “Numerical simulation of high-pressure gas atomization of two-phase flow: Effect of gas pressure on droplet size distribution,” Advanced Powder Technology, in press ( 2019).
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  • Haghshenas, M., Wilson, J. & Kumar, R. Finite Volume Ghost Fluid Method Implementation of Interfacial Forces in PISO Loop. Journal of Computational Physics, 2018. (IF: 2.744).

  • M. Haghshenas, J.A. Wilson and R. Kumar, “Algebraic coupled level set-volume of fluid method for surface tension dominant two-phase flow,” Int. J. Multiphase Flow, 90, pp. 13-28, 2017.
  • Castillo-Orozco, E., Kar, A. & Kumar, R. Electrospray mode transition of microdroplets with semiconductor nanoparticle suspension. Scientific Reports 7, 5144 (2017).

  • A. Karbalaei, R. Kumar and H.J. Cho, “Thermocapillarity in Microfluidics – A Review,” Micromachines, 7(1), 13, 2016.

  • E. Castillo-Orozco, A. Davanlou, P.K. Choudhury and R. Kumar, "Droplet Impact on Deep Liquid Pools: Formation of Rayleigh Jet and Daughter Droplets," Physical Review E,92, 053022, 2015. doi: 10.1103/PhysRevE.92.053022.

  • A.Davanlou and R. Kumar, “Passive mixing enhancement of microliter droplets in a thermocapillary environment,”  Microfluidics and Nanofluidics, 19(6), pp. 1507- 1513, 2015. doi: 10.1007/s10404-015-1656-3.

  • A.Davanlou and R. Kumar, “Counter-current motion of a droplet levitated on a liquid film undergoing Marangoni convection,”  Int. J Heat Mass Transfer, 89, pp. 345-352, 2015. doi:10.1016/j.ijheatmasstransfer.2015.05.036.

  • A.Davanlou and R. Kumar, “Thermally induced collision of droplets in an immiscible outer fluid,” Scientific Reports (Nature), Vol. 5, Article # 9531, 2015. Doi: 10.1038/srep09531.

  • A. Davanlou, J. D. Lee, S. Basu and R. Kumar, "Effect of viscosity and surface tension on breakup and coalescence of bicomponent sprays," Chem. Eng. Sci., 131, pp. 243-255, 2015. Doi:10.1016/j.ces.2015.03.057.

  • J. D. Wehking and R. Kumar, "Droplet actuation in an electrified microfluidic network," Lab on a Chip, 15(3), pp. 793-801, 2015.

  • A. Davanlou, H.J. Cho and R. Kumar, "Motion of spherical droplets against Marangoni convection flow in a thin liquid film," J. Heat Transfer136(8), 080915, 2014.

  • J.D. Wehking, M. Gabany, L. Chew, R. Kumar, “Effects of viscosity, interfacial tension, and flow geometry on droplet formation in a microfluidic T-junction,” Microfluidics and Nanofluidics16, pp. 441-453, 2014.

  • A. Miglani, S. Basu and R. Kumar, "Suppression of instabilities in burning droplets using preferential acoustic perturbations," Combustion and Flame161 (12), pp. 3181-3190, 2014.

  • A. Sanyal, S. Basu and R. Kumar, “Experimental analysis of shape deformation of evaporating droplet using Legendre polynomials,” Physics Letters A, 378, pp. 539-5482014.

  • A. Miglani, S. Basu and R. Kumar, “Insight into Instabilities in burning droplets for engineering new generation fuel droplets,” Physics of Fluids26, 032101, 2014.

  • P. Deepu, S. Basu and R. Kumar, "Multimodal shape oscillations of droplets excited by an air stream," Chem. Eng. Sci., 114, pp. 85-93, 2014.

  • A. Gupta, H.S. Matharoo, D. Makkar and R. Kumar, "Droplet Formation via Squeezing Mechanism in a Microfluidic Flow-Focusing Device," Computers and Fluids100, pp. 218-2262014.

  • J.D. Wehking, L. Chew and R. Kumar, “Droplet deformation and manipulation in an electrified  microchannel,” Appl. Phys. Lett, 103, 054101, 2013.

  • R. Shabani, R. Kumar and H.J. Cho, "Droplets on liquid surfaces: Dual equilibrium states and their energy barrier," Appl. Phys. Lett102, 184101, 2013.

  • J. Wilson, J.D. Wehking and R. Kumar, “Uniform alumina microspheres from Temperature Induced Forming in a microfluidic T-junction,”  Appl. Phys. Lett., 103, 203115, 2013.

  • S. Basu, E. Tijerino and R. Kumar, "Insight into morphology changes of nanoparticle laden droplets in acoustic field," Appl. Phys. Lett102, 141602, 2013.

  • B. Pathak, P. Deepu, S. Basu and R. Kumar, "Modeling of agglomeration inside a droplet with nanosuspensions in an acoustic field," Int. J Heat Mass Transfer59, pp. 161-166, 2013.

  • P. Deepu, S. Basu and R. Kumar, “Vaporization Dynamics of Functional Droplets in a Hot Laminar Air Jet,” Int. J Heat Mass Transfer33, Issues 1-22, pp. 69-79, 2013.

  • S. Basu, A. Saha and R. Kumar, "Criteria for Thermally Induced Atomization and Catastrophic Breakup of Acoustically Levitated Droplet," Int. J Heat Mass Transfer59, pp. 316–327, 2013.

  • A. Miglani, D. Joo, S. Basu and R. Kumar, “Nucleation Dynamics and Pool Boiling Characteristics of High Pressure Refrigerant Using Thermochromic Liquid Crystals,” Int. J Heat Mass Transfer60, pp. 188-200, 2013.

  • B. Pathak, S. Basu and R. Kumar, "Heat and Mass Transfer and Chemical Transformation in a cerium nitrate droplet, Int. J Heat Mass Transfer63, pp. 301-312, 2013.

  • E. Tijerino, S. Basu and R. Kumar, “Nanoparticle agglomeration in an evaporating levitated droplet for different acoustic amplitudes,”  J Applied Physics113, 0343072013.

  • P. Deepu, S. Basu and R. Kumar, “Dynamics and Fracture of ligaments from a droplet on a vibrating surface,” Physics of Fluids25, 082106, 2013.

  • J. D. Lee and R. Kumar, "Laboratory Study of Hydrogen Sulfide Removal in Slug Flows in a High Pressure Crude Oil Loop," J. Petroleum Science and Engineering103, pp. 72–79, 2013.

  • D. Vazquez and R. Kumar, "Surface Effects of Ribbon Heaters on Critical Heat Flux in Nanofluid Boiling," Int. Comm. Heat Mass Transfer41, pp. 1–9, 2013.

  • J. D. Lee, S. Basu and R. Kumar, “Comparison and Cross-Validation of Optical Techniques in Different Swirl Spray Regimes,” Atomization and Sprays, 23(8), pp.697-724, 2013.

  • A. Saha, J. Lee, S. Basu and R. Kumar, "Breakup and Coalescence Characteristics of a Hollow Cone Swirling Spray," Physics of Fluids24, 124103, 2012.

  • A. Saha, S. Basu and R. Kumar, “Scaling Analysis: Equivalence of Convective and Radiative Heating of Levitated Droplet,” Applied Physics Letters100, 204104, 2012.

  •  A. Saha, S. Basu and R. Kumar, “Thermally Induced Secondary Atomization of Droplet in an Acoustic Field,” Applied Physics Letters, 100, Issue 5, 054101, 2012.

  • P. Deepu, S. Basu, A. Saha and R. Kumar, “Spreading and Atomization of Droplets on a Vibrating Surface in a Standing Pressure Field,” Applied Physics Letters101, 143108, 2012.

  • A. Saha, S. Basu and R. Kumar, “Effects of Acoustic Streaming-induced Flow in Evaporating Nanofluid Droplets,” J Fluid Mechanics692, pp. 207-219, 2012.

  • X. Gu, S. Basu and R. Kumar, “Dispersion and Vaporization of Biofuels and Conventional Fuels in a Crossflow Pre-mixer,” Int. J Heat Mass Transfer56, Issues 1-3, pp. 336-346, 2012; featured online on Renewable Energy Global Innovations http://reginnovations.com

  • A. Saha, S. Basu and R. Kumar, “Particle Image Velocimetry and Infrared Thermography in a Levitated Droplet with Nanosilica Suspensions,” Experiments in Fluids52, pp. 795-807, 2012.

  • A. Saha, S. Basu and R. Kumar, "Velocity and Rotation Measurements in Acoustically  Levitated Droplets,"  Physics Letters A, 376, Issue 45, 3185-3191, 2012.

  • X. Gu, S. Basu and R. Kumar, “Vaporization and Collision Modeling of Liquid Fuel Sprays in a Co-axial Fuel and Air Pre-mixer,” Int. J Heat Mass Transfer55, Issues 19-20, pp. 5322-5335, 2012.

  • X. Gu, S. Basu and R. Kumar, “Correlations of Vaporization Performance of Conventional and Biofuel Sprays in a Crossflow Heated Chamber,” Int. Comm. Heat Mass Transfer, 39, Issue 10, pp. 1478-1486, 2012.

  • E. Yakshi-Tafti, R. Kumar and H.J. Cho, “Measurement of Surface Interfacial Tension as a function of temperature Using Pendant Droplet Images,” Int. J. Optomechatronics5, pp. 393-403, 2011.

  • N. Aminimanesh, S. Basu and R. Kumar, “Modeling of a Reacting Nanofilm on a Composite Substrate,” Energy36, Issue 3, pp. 1688-1697, 2011.

  • L.Zea, D. Cooper and R. Kumar, “Hydrogen Sulfide Absorption Phenomena in Brine/Oil Mixtures,” SPE Journal16 (4), pp.  931-939, 2011.

  • A.Gupta and R. Kumar, “Two-Dimensional Lattice Boltzmann Model for Droplet Impingement and Breakup in Low Density Ratio Liquid,” Comm. Comp. Phys., 10, pp. 767-784, 2011.

  • E. Yakshi-Tafti, H.J. Cho and R. Kumar, “Diffusive Mixing through Velocity Profile Variation in Microchannels,” Experiments in Fluids, 50, #3, pp. 535-545, 2011.

  • E. Yakshi-Tafti, H.J. Cho and R. Kumar, “Backward Facing Step Flow in Microchannels Using Particle Image Velocimetry,” J Thermophysics and Heat Transfer, 25, #1, pp. 96-103, 2011.

  • E. Yakshi-Tafti, G. Londe, A. Chunder, L. Zhai, R. Kumar and H.J. Cho, “Wettability Control and Flow Regulation using a Nanostructure-embedded Surface,” J. Nanoscience and Nanotechnology11, pp. 1-4, 2011.

  • R. Kumar, E. Tijerino, A. Saha and S. Basu, “Structural morphology of acoustically levitated and heated nanosilica droplet,” Applied Physics Letters97, 123106, 2010.

  • A.Saha, S. Basu, C. Suryanarayana and R. Kumar, “Experimental Analysis of Thermophysical Processes in Acoustically Levitated Heated Droplets,” Int. J. Heat Mass Transfer53, pp.5663-5674, 2010.

  • A.Gupta and R. Kumar, “Flow Regime Transition at High Capillary Numbers in a Microfluidic T-junction: Viscosity Contrast and Geometry Effect,” Physics of Fluids22, 122001, 2010.

  • N. Aminimanesh, S. Basu and R. Kumar, “Experimental Flame Speed in Multi-Layered Nano-Energetic Materials,” Combustion and Flame157, # 3, pp. 476-480, 2010.

  • S.M.S. Murshed, K. Vereen, D. Strayer and R. Kumar, “Experimental Investigation of Bubble Nucleation of a Refrigerant in Pressurized Boiling Flows,” Energy35, pp.5143-5150, 2010.

  • A.Saha, R. Kumar and S. Basu, “Infrared thermography and numerical study of vaporization characteristics of pure and blended bio-fuel droplets,” Int. J. Heat and Mass Transfer, 53, pp. 3862-3873, 2010.

  • A.Gupta and R. Kumar, “Effect of Geometry on Droplet Formation in the Squeezing Regime in a Microfluidic T-Junction,” J Microfluidics Nanofluidics8, pp. 799-812, 2010.

  • E. Yakshi-Tafti, H.J. Cho and R. Kumar, “Droplet Actuation on a Liquid Layer Due to Thermocapillary Motion: Shape Effect,” Applied Physics Letters96, 264101, 2010.

  • L. Zea, A.R. Diaz and C.K. Shepherd, R. Kumar, “Surface Extra Vehicular Activity Emergency Scenario Management: Tools, Procedures and Geologically-Related Implications,” Acta Astronautica67, pp. 60-70, 2010.

  • A.Gupta and R. Kumar, “Droplet impingement and breakup on a dry surface,” Computers and Fluids39, Issue 9, pp. 1696-1703, 2010.

  • S. Basu, D. E. Lambe and R. Kumar, “Water Vapor and Carbon dioxide Species Measurements in Narrow Channels,” Int. J Heat Mass Transfer53, Issue 4, pp. 703-714, 2010.

  • E. Yakshi-Tafti, H.J. Cho and R. Kumar, “Impact of Drops on the Surface of Immiscible Liquids,” J. Colloid and Interface Science350, pp. 373–376, 2010.

  • E. Yakhshi-Tafti, H.J. Cho, and R. Kumar, “Discrete Droplet Manipulation on Liquid Platforms using Thermal Gradients,” Procedia Chemistry1, pp. 1519-1522, 2009.

  • A.Gupta, S.M.S. Murshed and R. Kumar, “Droplet Formation and Stability of Flows in a Microfluidic T-Junction,” Applied Physics Letters94, 164107, 2009.

  • R. Kumar and D. Milanova, “Effect of Surface Tension on Nanotube Nanofluids,” Applied Physics Letters94, p. 073107, 2009; also featured in Virtual J Nanoscale Science and Technology, Mar 2, 2009.

  • P. Sachdeva and R. Kumar, “Effect of Hydration Layer and Surface Wettability in Enhancing Thermal Conductivity of Nanofluids,” Applied Physics Letters95, 223105, 2009; also featured in Virtual J Biological Physics, Dec 15, 2009.

  • R. Kumar and D. Milanova, “Dispersion and Surface Characteristics of Nano-Oxide Suspensions,” Ann. N.Y. Acad. Sci., 1161, pp.472-483, 2009.

  • X. Gu, A. Gupta and R. Kumar, “Lattice Boltzmann Simulation of Drop Collision and Surface Impingement at High Density Ratio,” J. Thermophysics and Heat Transfer23, No. 4, pp. 773-785, 2009.

  • A.Mishra, N. Hasan, S. Sanghi and R. Kumar, “Two-Dimensional Buoyancy Driven Thermal Mixing in a Horizontally Partitioned Adiabatic Enclosure,” Physics of Fluids, 20, 063601, 2008.

  • E.Yakshi-Tafti, R. Kumar and J. Cho, “Effect of Laminar Velocity Profile Variation on Mixing in Microfluidic Devices-The Sigma Micromixer,” Applied Physics Letters, 93, 143504, 2008.

  • D. Milanova and R. Kumar, “Heat Transfer Behavior of Silica Nanoparticles in Pool Boiling Experiment,” J. Heat Transfer130, 042401-2, 2008 (Top 10 Most Downloaded Articles -- April 2008).

  • A.Gupta and R. Kumar, “Lattice Boltzmann Simulation to Study Multiple Bubble Dynamics,” International J Heat and Mass Transfer, 51, pp.5192-5203, 2008.

  • A.Gupta and R. Kumar, “Role of Brownian motion on the thermal conductivity enhancement of nanofluids,” Applied Physics Letters, 91, 223102, 2007.

  • A.Gupta and R. Kumar, “Three-Dimensional Turbulent Swirling Flow in a Cylinder: Experiments and Computations,” International J Heat and Fluid Flow, 28, pp.249-261, 2007.

  • R. Kumar, A. Sleiti, J. Kapat, “Unsteady Laminar Buoyant Flow Through Rectangular Vents in Large Enclosures,” J. Thermophysics and Heat Transfer, 20, No. 2, pp. 276-284, 2006.

  • D. Milanova and R. Kumar, “Role of Ions in Pool Boiling Heat Transfer of Pure and Silica Nanofluids,” Applied Physics Letters87, p. 233107, 2005.

  • P.F. Vassallo, R. Kumar and S. D’Amico, “Pool boiling heat transfer experiments in silica-water nanofluids,” Int. J. Heat and Mass Transfer47, pp. 407-411, 2004.

  • R. Kumar, C.C. Maneri and T.D. Strayer, “Modeling and numerical prediction of flow boiling in a thin geometry,” J. Heat Transfer126, pp. 22-33, 2004.

  • R. Kumar, T.A. Trabold and C.C. Maneri, “Experiments and modeling in bubbly flows at elevated pressures,” J. Fluids Engineering, 125, pp. 469-478, 2003

  • R. Kumar and T.A. Trabold, “Effect of pressure with wall heating in annular two-Phase Flow,” J. Fluids Engineering, 125, pp. 84-96, 2003.

  • R. Kumar, M. Gottmann and K.R. Sridhar, “Film thickness and wave velocity measurements in a vertical duct,” J. Fluids Engineering124, pp. 634-642, 2002.

  •  P.F. Vassallo, T.A. Trabold and R. Kumar, “Slug to annular flow transitions in a vertical duct,” IntJ. Multiphase Flow27, pp. 119-145, 2001.

  • T.A. Trabold and R. Kumar, “High pressure annular two-phase flows in a narrow duct – Part I: local measurements in the droplet Field, J. Fluids Engineering122, pp. 364-374, 2000.

  • R. Kumar and T.A. Trabold, “High pressure annular two-phase flows in a narrow duct – Part II: three-field modeling, J. Fluids Engineering122, pp. 375-383, 2000.

  • T.A. Trabold and R. Kumar, “Vapor core turbulence in annular two-phase flow,” Experiments in Fluids28, pp. 187-194, 2000.

  • T.A. Trabold, R. Kumar and P.F. Vassallo, “Experimental study of dispersed droplets in high pressure annular flows,” J. Heat Transfer121, pp. 924-933, 1999.

  • G.J. Kirouac, T.A. Trabold, P.F. Vassallo, W.E. Moore and R. Kumar, “Instrumentation Development for Multi-Dimensional Two-Phase Modeling,” J. Experimental Thermal FluidScience20 (2), pp.79-93, 1999.

  • P.F. Vassallo and R. Kumar, “Liquid and Gas Velocity Measurements Using LDV in Air-Water Duct Flow,” J. Experimental Thermal Fluid Science19, pp.85-92, 1999.

  • R. Kumar, “Three-Dimensional Natural Convective Flow in a Vertical Annulus with Longitudinal Fins,” Int. J. Heat and Mass Transfer40, No. 14, pp. 3323-3334, 1997.

  • T.A. Conover, R. Kumar and J.S. Kapat, “Buoyant Pulsating Exchange Flow through a Vent,” J. Heat Transfer117, pp. 641-648, 1995.

  • M. Singhal and R. Kumar, “Unsteady Buoyancy Exchange Flow through a Horizontal Partition,” J. Heat Transfer117, No.2, pp. 515-520, 1995.

  • V.R. Desai, N.M. Aziz and R. Kumar, “Advances in Cross-Flow Turbine Technology,” Int. Water Power, pp. 50-56, April, 1994.

  • R. Kumar and S. Kannan, “Drop Size Measurement in a Two-Phase Swirling Flow Using Image Processing Techniques,” Int. J. Heat and Mass Transfer37, No. 4, pp.  559-570, 1994.

  • R. Kumar and T.A. Conover, “Flow Visualization Studies of a Swirling Flow in a Cylinder,” J. Experimental Thermal Science, 7, No. 3, pp. 254-262, 1993.

  • S. Ramanathan and R. Kumar, “Correlations for Natural Convection Between Heated Vertical Plates,” J. Heat Transfer113, No. 1, pp. 97-107, 1991.

  • R. Kumar and M.A. Kalam, “Laminar thermal convection between vertical coaxial isothermal cylinders,” Int. J. Heat and Mass Transfer34, No. 2, pp. 513-524, 1991.

  • R. Kumar and M. Keyhani, “Flow Visualization Studies of Natural Convective Flow in a Horizontal Cylindrical Annulus,” J. Heat Transfer112, No. 3, pp. 784-787, 1990.

  • J. Khan and R. Kumar, “Natural Convection in Vertical Annuli: A Numerical Study for Constant Heat Flux on the Inner Wall,” J. Heat Transfer111, No. 4, pp. 909-915, 1989.

  • R. Kumar, “Laboratory Studies of Thermal Convection in the Interface Under a Stable Layer,” Int. J. Heat and Mass Transfer32, pp. 735-749, 1989.

  • R. Kumar and T.D. Yuan, “Recirculating Mixed Convection Flow in Rectangular Cavities,” J. Thermophysics and Heat Transfer3, pp. 321-329, 1989.

  • R. Kumar, “Study of Natural Convection in Horizontal Annuli,” Int. J. Heat and Mass Transfer31, pp. 1147-1158, 1988.

  • S. Ramanathan and R. Kumar, “Comparison of Boundary Fitted Coordinates with Finite Element Approach for Solution of Conduction Problems,” Numerical Heat Transfer14, pp. 187-211, 1988.

  • D.N. Mahony, R. Kumar and E.H. Bishop, “Numerical Investigation of Variable Property Effects on Laminar Natural Convection of Gases in Horizontal Cylindrical Annuli,” J. Heat Transfer108, pp. 783-789, 1986.

  • R. Kumar and R.J. Adrian, “Higher Order Moments in the Entrainment Zone of Unsteady Turbulent Penetrative Convection,” J. Heat Transfer, 108, pp. 323-329, 1986.