Well-posedness of the extrusion model described by coupled hyperbolic   systems with a free boundary
  In this paper, we consider the well-posedness of the Cauchy problem for a physical model of the extrusion process, which is described by two systems of conservation laws with a free boundary. By suitable change of coordinates and fixed point argument, we obtain the existence, uniqueness and regularity of the weak solution to this Cauchy problem. 
Peipei Shang, Mamadou Diagne and Zhiqiang Wang
math.AP