The objectives of this book have been to restrict the discussion to results based on rigorously constructed physical theory. Thus in this chapter a couple of stability problems which, subject to the assumptions described, present solvable problems associated with solid flow. Generalizing the theory describing the flow of dilute suspensions will also be discussed. Here it is noted that new dynamic variables are required making the resulting thermodynamics much different than that which was discussed in previous chapters. It is

hoped that these special cases will yield insight into the problem of granular flow and the nature of the problems that must be overcome.