Comparison between the Lyα line profiles emerging dust free homogeneous shell (dotted blue lines), weakly clumpy shell (dashed magenta lines) and extremely clumpy shells (thick red lines) under different expansion velocities v_exp. All homogeneous and clumpy shells have for common parameters: = 2 × 10²⁰/cm², b = 40 km s^-1, = 0, and v_exp = 0, 100, 300, 400 km s^-1. Furthermore, both weakly and extremely clumpy media are built by adopting the following parameters: FF = 0.23, CF = 0.997 (R_min = 49 and R_max = 64 cells), and n_IC/n_C = 0.01 (weakly clumpy shell) and 0.00 (extremely clumpy shell).