Particle-Deposition

Composite particle dry-deposition model from Seinfeld & Pandis (2006), Atmospheric Chemistry and Physics, 2nd ed., Chapter 19 (Dry Deposition). Given the surface-layer friction velocity and an aerosol particle's properties it computes the particle dry deposition velocity v_d (Eq. 19.7) and the resulting downward deposition flux F (Eq. 19.1). Eq. 19.7, v_d = 1/(r_a + r_b + r_a*r_b*v_s) + v_s, combines the resistance-network pathway -- turbulent transport through the aerodynamic resistance r_a and the quasi-laminar boundary-layer resistance r_b, with the r_a*r_b*v_s cross term capturing gravitational settling acting inside the resistance network -- with a direct gravitational-settling term v_s; the flux F = -v_d*C (Eq. 19.1) is negative for downward transport. The competition between Brownian diffusion (efficient for sub-0.1 um particles) and inertial impaction (efficient for super-um particles) leaves a deposition-velocity minimum at accumulation-mode sizes. Migrated from AtmosphericDeposition.jl@e4468c79 src/seinfeld_pandis_ch19.jl:479 (the DryDepositionParticle @component), which composes three MTK subsystems via System(eqs, t; systems=[aero, settling, qlam]). Represented here as a subsystem-composed ESS model (spec §4.7): the aero subsystem inlines the already-migrated AerodynamicResistance component (aerodynamic_resistance.esm, esm-x8pg), settling inlines ParticleSettling (particle_settling.esm, esm-egwt) and qlam inlines QuasiLaminarResistanceParticle (quasi_laminar_particle.esm, esm-brbr), wired by six top-level coupling equations. Purely algebraic (no D() time-derivative anywhere): u_star and C are input parameters; v_d and F are algebraic state outputs.

Zhang et al. (2001) quasi-laminar (boundary-layer) resistance r_b for particle dry deposition, Seinfeld & Pandis (2006) Ch. 19 Eq. 19.27. r_b = 1/(3*u_star*(E_B+E_IM+E_IN)*R_1) sums three size-dependent collection mechanisms — Brownian diffusion E_B (Eq. 19.21), inertial impaction E_IM (Eq. 19.22), and interception E_IN (Eq. 19.25) — scaled by the friction velocity u_star and the rebound-correction sticking fraction R_1 (Eq. 19.26). The competition between diffusion (efficient for sub-0.1 um particles) and impaction (efficient for super-um particles) leaves a deposition minimum at accumulation-mode sizes. Migrated from AtmosphericDeposition.jl@e4468c79 src/seinfeld_pandis_ch19.jl:234 (`QuasiLaminarResistanceParticle` @component). The seven upstream equations are migrated verbatim and one-to-one; the five input @parameters, the @constant g, and the three externally-supplied input @variables (u_star, v_s, D_diff) are all parameters, and the seven equation-defined quantities (Sc, St, E_B, E_IM, E_IN, R_1, r_b) are the algebraic outputs.