Evolution of the UV escape fraction f_esc(UV) as a function of the dust optical depth () in three different shell geometries: a homogeneous shell (n_IC/n_C = 1.00), a weakly clumpy shell (n_IC/n_C = 0.01) and an extremely clumpy shell (n_IC/n_C = 0.00). The clumpy media are defined with FF = 0.23 and CF = 0.997 (R_min = 49 and R_max = 64 cells). For comparison we also plot the curves for and f_esc = exp(−τ_d), which respectively describe the upper and the lower limit of the continuum escape fraction in homogeneous media.