The Collision Rate of Nonspherical Particles and Aggregates for all Diffusive Knudsen Numbers

Figures & data

FIG. 1 Schematic of the procedures used for (a) Smoluchowski radius and (b) projected area calculation for a colliding pair of particles. (Color figure available online.)

FIG. 2 Schematic of the mean first passage time calculation procedure. (Color figure available online.)

TABLE 1 Summary of the properties of the ten test aggregate pairs used in mean first passage time simulations. Reported R_S,i , R_S,j , PA_i , PA_j , R_S,ij , and PA_ij are for aggregates with primary particle radii of 1 (arbitrary units)

FIG. 3 (a). Summary of the H(Kn_D ) results obtained with mean first passage time simulations for ten test aggregate pairs. For comparison, H(Kn_D ) curves corresponding to the continuum limit (12a), free molecular limit (12b), and regression equation from (Gopalakrishnan and Hogan [2011], Equation (13)) are shown. (b) The relative difference between H(Kn_D ) inferred from mean first passage time calculations and Equation (13) as a function of Kn_D . Relative difference is defined in the text. (Color figure available online.)

FIG. 4 Depiction of the phase space noting when gas to particle momentum transfer and particle–particle mass transfer (collisions) lie within the continuum, transition, and free molecular regimes. (Color figure available online.)

TABLE 2 Summary of the properties of the four test aggregate pairs used for comparison to previously developed aggregate collision kernel models. Reported length scales are for aggregates with primary particle radii of 1 (arbitrary units)

FIG. 5 Comparison of the relative difference between H predicted by (a) Cho et al. (2011) and (b) Rogak and Flagan (1992) and H predicted by Equation (13), as a function of Kn_D , for four test aggregate pairs with properties noted in Table 2. (Color figure available online.)

FIG. 6 (a) A comparison of PA_ij to R_S,ij for test aggregate pairs. The black line denotes the curve PA_ij = πR² _S,ij . (b) A comparison between calculated R_S,ij and a regression Equation (21) developed to predict R_S,ij from R_S,i , and R_S,j . (Color figure available online.)

FIG. 7 (a) The average Smoluchowski radii and (b) and orientationally averaged projected area of aggregates formed from the collision of test aggregate pairs, as functions of Kn_D . (Color figure available online.)

Cho , K. , Chung , K. S. and Biswas , P. 2011 . Coagulation Coefficient of Agglomerates with Different Fractal Dimensions . Aerosol Sci. Tech. , 45 ( 6 ) : 740 – 743 .

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Rogak , S. N. and Flagan , R. C. 1992 . Coagulation of Aerosol Agglomerates in the Transition Regime . J. Colloid Interf. Sci. , 151 ( 1 ) : 203 – 224 .

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