Arresting of interfacial phase separation with an imposed flow

We experimentally investigate displacement of a more viscous liquid by a less viscous one in a Hele-Shaw cell using an aqueous two phase system, where phase separation occurs in the growing liquid-liquid interfacial region, by varying the injection flow rate and the phase separation rate. We show that the degree of the interfacial phase separation scales as a unique function of the ratio of the flow and phase separation rates and it decreases with the ratio. These results demonstrate that the interfacial phase separation is arrested by the imposed flow and determined by competition between the flow and phase separation rates. The arresting effect and the mechanism are numerically verified.