CPM Seminar

A liquid foam is a remarkable material. Composed almost entirely of gas, it is able to flow like a liquid and resist shear like a solid. A static foam is a glass in the sense that it is a disordered solid. The energy required to overcome the barriers to rearrange bubbles is of order 10⁵ to 10⁷ kT, so thermal energy is insignificant. When a foam is sheared, however, there is enough energy to overcome the barriers and bubbles rearrange. Numerical simulations on a simple model of foam show that a steady state sheared foam shares some qualitative features with a molecular liquid. For example, the motion of bubbles is diffusive and the velocity fluctuations around the average flow are Gaussian. This suggests that the shear may produce an effective "temperature".

Thursday, January 29th, 13:15
Ernest Rutherford Physics Building, Boardroom (room 105)