4 марта профессор Северо-западного университета США, член Национальной академии наук Стефан Дэвис прочитает в НГУ лекцию «Динамика чистых пен».
Dynamics of clean foams by Stephen H. Davis, Northwestern University:
The most common foams studied in the literature as composed of air bubbles in water plus surfactant that saturates the air-water interface. Such foams may have essentially zero liquid fraction and are studied as three-dimensional static structures. If the liquid fraction is non-zero, there can still be stable static configurations as long as gravity is negligible. This talk will focus on a third type of foam, one which has no surfactant; the prototype of this is a metallic form, liquid metal with crowded gas bubbles ( low liquid fraction ). Such foams have no static equilibria and so evolve in time. The liquid forms thin films that thin due to surface tension and when they have thinned sufficiently, will rupture due to van der Waals attractions resulting in adjacent bubbles coalescing. This coarsening until there are no longer any instabilities. A new network approach is used to follow the evolution in 2D : the thin films have quasi-one-dimensional flows and the Plateau borders are nodes that move subject to Newton’s laws. The film instability is monitored by using a theoretical rupture condition. The foams can then be followed for long times and statistical laws derived for the multiple ruptures.
Лекция состоится 4 марта, в 16:20, в ауд. 4117 нового корпуса НГУ. Язык лекции — английский.
