RT Journal Article T1 The mesa problem: diffusion patterns for ut=∇⋅(um∇u) as m→+∞ . A1 Elliot, C. M. A1 Herrero, Miguel A. A1 King, J. R. A1 Ockendon, J.R. AB In this paper we consider the limit m→+∞ of solutions of the porous-medium equation ut = ∇•(um∇u)(xεRN), with N > 1. We conjecture that, for initial data with a unique maximum, the evolution is characterized by the onset of a ‘mesa’ region, in which the solution is nearly spatially independent, surrounded by a region in which u is nearly equal to its initial value. The transition between these regions occurs near a surface which is identified with the free boundary in a certain Stefan problem which can be studied using variational inequalities. Moreover, singular-perturbation theory can be used to describe the structure of the transition region. PB Oxford University Press SN 0272-4960 YR 1986 FD 1986 LK https://hdl.handle.net/20.500.14352/64758 UL https://hdl.handle.net/20.500.14352/64758 DS Docta Complutense RD 12 abr 2025