3D dust-void structure for three different values of δ in the gas-dominated regime (St = 0.04), for a planet with M_p = 1.5M_⊕. Top: snapshot (calculated at t = 70 orbits) in the case of δ = 10⁻⁵. A low-density trench forms in front of the planet instead of a filament. Middle: case with δ = 10⁻⁴. The dust-void structure resembles the shape found in 2D simulations but without the high-density ring-shaped barrier. Bottom: dust-void and filament disappearing for δ = 3 × 10⁻³ (snapshot calculated at t = 100 orbits).