Film drainage and the lifetime of bubbles

[1] We present the results of new laboratory experiments that provide constraints on inter bubble film thinning and bubble coalescence as a consequence of liquid expulsion by gravitational and capillary forces. To ensure dynamic similarity to magmatic systems, the experiments are at small Reynolds numbers Re 1 ð Þ and cover a wide range of Bond numbers (10 3 Bo 10). Results indicate that at Bo< 0.25 film drainage is due to capillary forces, whereas at Bo> 0.25 gravitational forces result in film thinning. The film drainage time scale is given by t C ln ( ) and is orders of magnitude faster than often assumed for magmatic systems. Here, C 10 is an empirical constant and is the ratio of initial film thickness to film thickness at the time of rupture and is the characteristic capillary or buoyancy time scale at values of Bo< 0.25 and Bo> 0.25, respectively.