Time evolution of and the dust scale height at the maximum ρ_d∕ρ_g locations scaled by the initial one (= H_p). The back reaction to diffusion is included with K = 1 in panel b, but not (K = 0) in panel a, while the back reaction to v_r is included in both panels a and b. The light blue, magenta, blue, green, and red curves are the results with F_p/g = 0.05, 0.1, 0.2, 0.4 and 0.8, respectively. The other parameters are fixed as α_acc = 10⁻², Δx_subl= 0.1, and Δz_subl = 0.03. The diffusion parameters are α_Dz = α_Dr = 10⁻⁵ in panel a and α_Dz = α_Dr = 10⁻⁴ in panel b.