学 术 报 告

题目：Spreading speed and asymptotic profiles for solutions in free boundary problems for nonlinear advection-diffusion equations

报告人： H. Matsuzawa (Numazu National College of Technology)

Abstract: We study nonlinear advection-diffusion problems of the form u_t - u_{xx} + /beta u_x = f(u) with free boundaries x = h(t) and x = g(t). Such a problem may be used to describe the spreading of a biological or chemical species with the free boundaries representing the expanding fronts. The term /beta u_x represents an effect of advective environments. For logistic nonlinearity, it has been shown by Gu, Lin and Lou that the asymptotic spreading speeds of the two fronts h(t) and g(t) are different due to the advection term. In this paper, when the nonlinear function is a monostable, bistable or of combustion type, we give a much sharper estimate for the different spreading speeds of the fronts, and describe how the solution approaches a semi-wave when spreading happens. We develop new approaches and extend the result of Du, Matsuzawa and Zhou to the problem with an advection term.

时间：3月24日 15:00-16:00

地点：致远楼102