Nonexistence of one of the free boundaries in a degenerate equation in filtration theory

Abstract

We study the qualitative behaviour of solutions of the equation ut−(um)xx+b⋅(uλ)x=0 when it models some evaporation phenomena, λ<1≤m. We show strong differences with respect to the porous media equation; there is no right free boundary. We also study the behaviour of the left free boundary