A NOTE ON THE INITIAL CONDITION FOR THE FORMATION OF FOAMS

It is shown that the initial condition which is input into the model d escribing bubble growth in liquids needs to be re-examined for the cas e of rapid foam formation. The initial condition that is assumed in fo am formation is the critical nucleus; it is from here that the expansi on occurs. For a rapid foam formation the initial condition needs to b e changed, the size adopted is that of a bubble which allows the onset of instability. This instability occurs when the pressure difference between the inside of the bubble and the outside is small and approach ing a difference of the order of 1 to 2 atmospheres, this corresponds to bubble sizes of 10(-4) m. This is the value that should be used as the initial condition in the differential equations expressing the gro wth of bubbles in the formation of a liquid foam.