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Effect of relative humidity on heat transfer across the surface of an evaporating water droplet in air flow


A three-dimensional direct numerical simulation (DNS) is applied to flows inside and outside an evaporating spherical water droplet in air, and the effect of relative humidity on the heat transfer between the droplet and ambient air is investigated. The initial air temperature is set to be 15 K higher than the initial droplet temperature. The results show that the local evaporation heat loss indicates the maximum on the front of the droplet and decreases on going from the front to the rear, and the reduction on the rear becomes marked for high-droplet Reynolds numbers. This is because the evaporation rate is suppressed on the rear surface by the presence of flow separations behind the droplet. The droplet temperature decreases in the low-humidity condition, whereas it increases in the high-humidity condition. This difference is caused by the heat balance of evaporation heat loss and convective heat gain from ambient air at the droplet surface.

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Baba, Y. & Kurose, R. 2008 Analysis and flamelet modeling for spray combustion. J. Fluid Mech. 612, 4579.
Bagchi, P. & Kottam, K. 2008 Effect of freestream isotropic turbulence on heat transfer from a sphere. Phys. Fluids 20, 073305.
Beard, K. V. & Pruppacher, H. R. 1971 A wind tunnel investigation of the rate of evaporation of small water drops falling at terminal velocity in air. J. Atmos. Sci. 28, 14551464.
Hanazaki, H. 1998 A numerical study of three-dimensional stratified flow past a sphere. J. Fluid Mech. 192, 393419.
Kim, I., Elghobashi, S. E. & Sirignano, W. A. 1995 Unsteady flow interactions between an advected cylindrical vortex tube and a spherical particle. J. Fluid Mech. 288, 123155.
Kurose, R. & Komori, S. 1999 Drag and lift forces on a rotating sphere in a linear shear flow. J. Fluid Mech. 384, 183206.
Kurose, R., Makino, H., Komori, S., Nakamura, M., Akamatsu, F. & Katsuki, M. 2003 Effects of outflow from surface of sphere on drag, shear lift, and scalar diffusion. Phys. Fluids 15, 23382351.
Kurose, R., Misumi, R. & Komori, S. 2001 Drag and lift forces acting on a spherical bubble in a linear shear flow. Intl J. Multiphase Flow 27, 124711258.
Masoudi, M. & Sirignano, W. A. 2000 Collision of a vortex with a vaporizing droplet. Intl J. Multiphase Flow 26, 19251949.
Miller, R. S. & Bellan, J. 1999 Direct numerical simulation of a confined three-dimensional gas mixing layer with one evaporating hydrocarbon-droplet-laden stream. J. Fluid Mech. 384, 293338.
Murray, F. W. 1967 On the computation of saturation vapor pressure. J. Appl. Meteorol. 6, 203204.
Nakamura, M., Akamatsu, F., Kurose, R. & Katsuki, M. 2005 Combustion mechanism of liquid fuel spray in a gaseous flame. Phys. Fluids 17, 123301.
Onishi, Y. 1990 On the macroscopic boundary conditions at the interface for a vapour-gas mixture. In Adiabatic Waves in Liquid–Vapor Systems (ed. Meier, G. E. A. & Thompson, P. A.), pp. 315324. Springer.
Sugioka, K. & Komori, S. 2005 The effects of droplets on mass transfer in wind-driven turbulence with breaking waves. Tran. JSPS (B) 71, 714 (in Japanese).
Sugioka, K. & Komori, S. 2007 Drag and lift forces acting on a spherical water droplet in homogeneous linear shear air flow. J. Fluid Mech. 570, 155175.
Welty, J. R., Wicks, C. E., Wilson, R. E. & Rorrer, E. 1984 Fundamentals of Momentum, Heat, and Mass Transfer. John Wiley & Sons.
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Journal of Fluid Mechanics
  • ISSN: 0022-1120
  • EISSN: 1469-7645
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