PARTICOLATO FISICA AMBIENTALE 2 Antonio Ballarin Denti

LE PARTICELLE Volume fraction of aerosol particles in 4 quite different locations

Stages in the absorption of gaseous SO 2 ina raindrop

Cattura di SO2 da parte di una goccia di pioggia c (r > R, t = 0) = c c (r, t ) = c c (R, t) = c s (t)=0

r R r = 0, t > 0 t > 0 r R c (r, t = 0) = 0 c (R, t) = c s c (r, t ) = c s

Cattura di SO2 da parte di una goccia di pioggia Characteristic diffusion times in air and water for some drop sizes τ air τ drop 2.5 × × × R(m)10 -3 (1 mm) (10 μm) D g = m 2 s -1 D a = m 2 s -1

Fluxes at the interface air-water drop. The interface may be considered flat at x = 0

Cattura di SO2 da parte di una goccia di pioggia

Derivation of Stokeslaw Fluid is flowing from bottom to top with a non-slip condition at the surface. On the left one finds the general coordinate system, on the right the forces at the surface of the sphere. The drag is determinated by the components of the pressure force and tangential force in the direction of the flow.

LE PARTICELLE Attrito su una singola particella