Oblique colisional effects of dust acoustic waves on electrostatic potential ϕ(1)=ϕξ(1)+ϕη(1) for θ = 30° (a) and θ = 45° (c) with n_2d(1d) = 0.1, n_i(1d) = 0.4, Z = 0.01, T_1d(i) = 10^–5, T_2d(i) = 10^–4, κ_e = 3, T_i(e) = 0.1, v_phξ = 0.045, v_phη = 0.045, M_1d(2d) = 150, and U₀ = 0.09. Panels (b) and (d) are contour plots of panels (a) and (c).