Computational Models for Simulating Multicomponent Aerosol Evaporation in the Upper Respiratory Airways

Figures & data

TABLE 1 Description of computational models implemented for droplet evaporation

Conditions: Model	Solution of the flow field	Spatially variable gas specific heat	Surface blowing	Internal droplet temperature gradient
ODE			X ^a
RMM1	X
RMM2	X	X
RMM3	X	X	X
DLM	X	X	X	X

FIG. 1 Axisymmetric two-dimensional geometry of a spherical droplet in a nearly infinite media (from Longest and Kleinstreuer 2004 with permission).

FIG. 2 Representative computational flow field results: (a) Velocity vectors, contours of velocity magnitude, and (b) mass fraction for an axisymmetric 480 cm n-heptane droplet far from the wall with T_∞ = 298 K, u_∞ = 100 cm/s ω_∞ = 0, and Re _p = 30.2 (from Longest and Kleinstreuer 2004 with permission).

FIG. 3 Comparison of two-dimensional simulation results for uniform flow to (a) Sherwood and (b) Nusselt number correlations of Clift et al. (1978) and Ranz and Marshall (1952).

FIG. 4 Computational estimates of normalized droplet surface area (d ²/d _o ²) over time compared to the experimental results of Runge et al. (1998) for (a) high volatility n-heptane with T_∞ = 298 K and Re _p = 30.2; (b) high volatility n-heptane with T_∞ = 272  K and Re _p = 107.3; (c) low volatility n-decane with T_∞ = 272  K and Re _p = 94.1; and (d) multicomponent 50:50 heptane-decane mixture with T_∞ = 272 K and Re _p = 107.0. Descriptions of the numerical models are given in Table 1.

FIG. 5 Variable property (RMM2) estimates of droplet temperature over time for: (a) n-heptane with T_∞ = 272 K and Re _p = 107.3; and (b) multicomponent 50:50 heptane–decane mixture with T_∞ = 272 K and Re _p = 107.0.

FIG. 6 Semiempirical and resolved-volume simulations of droplet evaporation for a multicomponent 50:50 heptane–decane mixture with T_∞ = 298 K and Re _p = 107. Results for RMM3 and the DLM are practically indistinguishable from the RMM2 solution.

FIG. 7 Computational estimates of normalized droplet surface area (d ²/d _o ² ) over time compared to the experimental results of Runge et al. (1998) for a twelve-component JP-8 surrogate mixture.

TABLE 2 Twelve component JP-8 surrogate

Component	Wt % Edwards and Maurice (2001)	Wt % Computed with RMM2
iso-octane	5.0	0.25
Methyl cyclohexane	5.0	0.25
m-xylene	5.0	0.25
Cyclooctane	5.0	0.25
Decane	15.0	7.0
Butyl benzene	5.0	3.0
1,2,4,5 tetramethyl benzene	5.0	14.0
Tetralin	5.0	15.0
Dodecane	20.0	23.0
1-methyl naphthalene	5.0	8.0
Tetradecane	15.0	17.0
Hexadecane	10.0	12.0

Longest , P. W. ,. and Kleinstreuer , C. 2004 . Interacting Effects of Uniform Flow, Plane Shear, and Near-Wall Proximity on the Heat and Mass Transfer of Respiratory Aerosols . Int. J. Heat Mass Transfer , 47 : 4745 – 4759 . http://dx.doi.org/10.1016%2Fj.ijheatmasstransfer.2004.05.029

 Web of Science ®Google Scholar

Clift , R. , Grace , J. R. and Weber , M. E. 1978 . Bubbles, Drops, and Particles. , New York : Academic Press .

 Google Scholar

Ranz , W. E. ,. and Marshall , W. R. 1952 . Evaporation from Drops . Chem. Eng. Prog. , 487 : 141 – 146 . 173 – 180 .

 Google Scholar

Runge , T. , Meske , M. and Polymeropoulou , C. E. 1998 . Low-Temperature Vaporization of JP-4 and JP-8 Fuel Droplets . Atomization Sprays , 8 : 25 – 44 .

 Web of Science ®Google Scholar

Edwards , T. ,. and Maurice , L. Q. 2001 . Surrogate Mixtures to Represent Complex Aviation and Rocket Fuels . J. Propul. and Power , 17 ( 2 ) : 461 – 466 . http://www.csa.com/htbin/linkabst.cgi?issn=0748-4658&vol=17&iss=2&firstpage=461

 Web of Science ®Google Scholar