报告题目：（一）Pseudo-combustion phenomena in advanced materials

（二）Flame acceleration in deflagration-to-detonation transition

报 告 人：（一）Mikhail Modestov，Nordita, Sweden

（二）Vitaliy Bychkov，瑞典Umea大学物理系

报告时间：3月5日（周二）下午2:00-4:00

报告地点：物理系三楼报告厅

报告摘要：（一）If we think about combustion process in the most general sense, than we can treat it as a process of matter transformation from one state to another, which happens in a very localized region. There is a big variety of phenomena where we can meet fronts of different nature. In this talk I will describe two examples of fronts from our recent studies. First I will talk about organic semiconductors and we will see that fronts of electrochemical doping resemble flame front corrugated by Darrieus-Landau instability. Secondly I will describe magnetization reversal in crystals of molecular magnets; due to close similarity to combustion it has been called magnetic deflagration. Apart to slow subsonic regime I will also consider main features of magnetic detonation.

（二）A premixed combustion front propagates either as a slow subsonic flame (deflagration) or fast supersonic detonation; their velocities differ by 3-4 orders of magnitude. However, at certain conditions a slow flame may spontaneously accelerate and trigger detonation. A deflagration-to-detonation transition (DDT) is the key point, for example, for explaining Thermonuclear Supernovae (Type Ia) and in the design of pulse-detonation engines of the new-generation aircrafts; it stands also behind many disasters like explosions in rockets, nuclear plants and mines. Spontaneous flame acceleration is the reason and the most important stage of the DDT. In this talk I will present our results on the flame acceleration process. The presentation includes both development of the classical Shelkin mechanism of flame acceleration in tubes with smooth walls, and the new ultra-fast mechanism of flame acceleration in obstructed channels, explained by our group. Moderation of the flame acceleration process at the developed stages and explosion triggering will be also discussed.