Linear-regime simulation results for initial density fluctuations following Eq. (23) with a flat power spectrum in a 2048 × 256 grid. Left: Perturbation profiles for (from top to bottom) density, velocity x and y components, and magnetic-field x and y components. Note that δu_x/c_s has been multiplied by 1/3 and δu_y/c_s by two, so all quantities can be visualized using the same color-bar scale. Right: Dimensionless 2D (top) and omnidirectional (bottom) density fluctuations’ power spectra, k²P_δρ/ρ0(k_x, k_y) and kE_δρ/ρ0(k), respectively.