Ratio D_⊥/D_∥ as a function of ρ′ for η = 0.99, compared to theorectical predictions and other numerical simulations. Filled diamonds: our simulation results. Star symbols: results from Casse et al. 2002. Solid curve: present theoretical prediction with best-fit D_∥ from simulations (see Fig. 2). Dashed curve: present theoretical prediction with analytical D_∥ = c²/(3ν_s). Dot-dashed curve: analytical prediction from Shalchi & Dosch (2009), their Eq. (15).