Frequency-wavenumber (ω–k) diagram for different values of the dust density (n_d) based on data from runs 1(ii–v). The dashed black lines are plotted from the linear dispersion of DA waves in each case, based on Eq. (10). The depicted ω–k plots were generated by using data in the time interval ω_pit = 0–640. The phase speeds of DASWs obtained as 0.13, 0.14, 0.15 and 0.16 [V_thi] when n_d is 0.005, 0.006, 0.007, and 0.008, respectively.