Dimensionless Size Spectra Evolution

We now consider size spectra corresponding to the three cases just developed. 

The initial distribution xj/oiii) was adapted from one measured in a power plant plume (see case d in Table 3 of Eltgroth and Hobbs, 1979). The dimensionless size distributions are presented in terms of the dimensionless mass distribution M(logDp,r), where PpX ) n M(log Dp, t) d log Dp is the mass of particles having logarithm of diameter in the range (log Dp, log Dp + d log Dp). Thus M is related to xj/ by 

It is necessary to specify the parameters S and o . The saturation ratio S will be chosen as 2.878 corresponding to a critical diameter D = AavfRT In 5 of O.OI fim for a sulfuric acid/water aerosol at 25 °C. The Kelvin parameter is then equal to 0.1282. Since S is taken independent of time, the growth laws / are functions of p only. 

FIGURE 12.14 Evolution of dimensionless aerosol mass distribution at dimensionless times r = 0, 0.2, 0.4, and 0.6 for diffusion-controlled growth with perfect ab.sorption (Seinfeld and Bassett, 1982). 

FIGURE 12.15 Aerosol mass distribution at dimensionless time r = 0.4 resulting from growth by diffusion, with and without perfect absorption, surface reaction, and volume reaction (Seinfeld and Bassett, 1982). 

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