@article {:/content/aip/journal/pof2/26/2/10.1063/1.4866641, title = {Mobilization of a trapped non-wetting fluid from a three-dimensional porous medium}, journal = {Physics of Fluids}, volume = {26}, number = {2}, year = {2014}, pages = {022002}, abstract = { We use\ confocal microscopy\ to directly\ visualize\ the formation and complex morphologies of trapped non-wetting fluid ganglia within a model\ 3D\ porous medium.\ The\ wetting\ fluid continues to\ flow\ around the ganglia after they form; this\ flow\ is characterized by a capillary number,\ Ca. We find that the ganglia configurations do not vary for small\ Ca; by contrast, as\ Ca\ is increased above a threshold value, the largest ganglia start to become mobilized and are ultimately removed from the medium. By combining our\ 3D\ visualization\ with\ measurements\ of the bulk transport, we show that this behavior can be quantitatively understood by balancing the\ viscous\ forces exerted on the ganglia with the pore-scale capillary forces that keep them trapped within the medium. Our work thus helps elucidate the fluid dynamics underlying the mobilization of a trapped non-wetting fluid from a\ 3D\ porous medium. }, doi = {http://dx.doi.org/10.1063/1.4866641}, url = {http://scitation.aip.org/content/aip/journal/pof2/26/2/10.1063/1.4866641}, author = {Datta, Sujit S. and Ramakrishnan, T. S. and Weitz, David A} }