报告人： Prof. Jack Xin
Variational Principles of KPP Front Speeds in Temporally Random Flows and Related Computations
Reaction-diffusion fronts in random flows appear in many scientific areas such as turbulent combustion, population dynamics of bio-species in the occean, pullution spreading in groundwater etc. Direct simulation of large time front speeds (spreading rates) are expensive and often inefficient. For quadratic reaction and its generalizations, so called Kolmogorov-Petrovsky-Piskunov (KPP) reactions, the large time front speeds are shown to obey variational principles where a key quantity is the almost sure Lyapunov exponent that can be quantified and computed from a reduced linear parabolic stochastic equation. Analytical bounds on the front speeds and numerical simulations based on the variational principle will be shown for time random flow fields (shear and cell flows).
报告时间： 2006年7月6日(周四) 上午10:00--11:00