We introduce a computational model for high-resolution simulations of particle-laden gravity currents. The features of the computational model are described in detail, and validation data are discussed. Physical results are presented that focus on the influence of particle entrainment from the underlying bed. As turbulent motions detach particles from the bottom surface, resuspended particles entrained over the entire length of the current are transferred to the current's head, causing it to become denser and potentially accelerating the front of the current. The conditions under which turbidity currents may become self-sustaining through particle entrainment are investigated as a function of slope angle, current and particle size, and particle concentration. The effect of computational domain size and initial aspect ratio of the current on the evolution of the current are also considered. Applications to flows traveling over a surface of varying slope angle, such as turbidity currents spreading down the continental slope, are modeled via a spatially varying gravity vector. Particular attention is given to the resulting particle deposits and erosion patterns.