This monograph has grown out of research we started in 1987, although the foun dations were laid in the 1970's when both of us were working on our doctoral theses, trying to generalize the now classic paper of Oleinik, Kalashnikov and Chzhou on nonlinear degenerate diffusion. Brian worked under the guidance of Bert Peletier at the University of Sussex in Brighton, England, and, later at Delft University of Technology in the Netherlands on extending the earlier mathematics to include nonlinear convection; while Robert worked at Lomonosov State Univer sity in Moscow under the supervision of Anatolii Kalashnikov on generalizing the earlier mathematics to include nonlinear absorption. We first met at a conference held in Rome in 1985. In 1987 we met again in Madrid at the invitation of Ildefonso Diaz, where we were both staying at 'La Residencia'. As providence would have it, the University 'Complutense' closed down during this visit in response to student demonstra tions, and, we were very much left to our own devices. It was natural that we should gravitate to a research topic of common interest. This turned out to be the characterization of the phenomenon of finite speed of propagation for nonlin ear reaction-convection-diffusion equations. Brian had just completed some work on this topic for nonlinear diffusion-convection, while Robert had earlier done the same for nonlinear diffusion-absorption. There was no question but that we bundle our efforts on the general situation.
Travelling waves are observed in many natural processes, ranging from the spread of diseases to the combustion of fuels. The book is concerned with characterizing such waves in phenomena described by a nonlinear diffusion-convection-reaction equation. The technique employed is new and can be briefly described as an integral or integrated approach to phase-plane analysis. It leads to results which were so far unobtainable, including the effects of degenerate diffusion and nonlinear convection, or are much sharper than those obtained previously. Applications are taken from the evolution of biological populations, diffusion of oxygen in tissue, heat transfer, thermal convection, combustion, flow in porous media, hydrology, soil-moisture flow, boundary layer theory, foam drainage, viscous fluid flow, turbulent fluid flow, the motion of plasma particles in a magnetic field, solar prominences, crystal growth, reaction chemistry, quenching, and other fields.In this way, the book brings together and improves a large number of results which have been obtained piecemeal in many different scientific disciplines.
It provides a reference work for applications of nonlinear diffusion, convection and reaction, and gives a state-of-the-art survey of the study of the occurrence of travelling waves in such applications.
