Fig. 4: DEM simulation setup.
From: Behaviors of lunar regolith simulants under varying gravitational conditions

A A funnel of throat diameter D = 1.75 mm and hopper angle α = 75 is filled with 1500 particles, ranging from d = 0.005 mm to 0.5 mm in diameter, and density ρ = 400 kg m−3. Gravity is applied in the negative y-direction. B The DMT model for contact forces between spheres of radii Ri and Rj, with velocities vi and vj, are split into normal and tangential components, governed by: their overlaps δij and ∆sij; spring constants Kn and Kt; damping coefficients γn and γt; a frictional coefficient, µ; cohesion parameter, ϕ.