Existence and uniqueness of solutions for a boundary value problem   arising from granular matter theory
  We consider a system of PDEs of Monge-Kantorovich type that, in the isotropic case, describes the stationary configurations of two-layers models in granular matter theory with a general source and a general boundary data. We propose a new weak formulation which is consistent with the physical model and permits us to prove existence and uniqueness results. 
Graziano Crasta, Annalisa Malusa
math.AP