The effect of insoluble surfactants on the motion and deformation of interacting bubbles

The effect of dilute, insoluble surfactant on the rise and deformation of buoyancy-driven interacting bubbles at finite Reynolds numbers is examined by numerical simulations. The average rise Reynolds number is around 3 - 6 depending on the strength of contaminant. A front tracking/finite difference technique is used to solve the governing equations inside and outside the bubbles and the variation of surface tension with the concentration of surfactant at the interface is modeled by a linear frame work. It is found that while a freely evolving array of clean bubbles rises slower than a regular array (i.e. single bubble), the opposite is true for the contaminated bubbles.