Experiments on chemically enhanced immiscible fluid displacements

This talk focuses on experiments conducted by displacing a vegetable oil within a capillary tube (diameter $<$ 1 mm) using an aqueous alkali solution. Estimates of the residual film were measured as a function of Reynolds (Re), viscous Atwood (At) and capillary (Ca) numbers. The pendant drop method was used to measure surface tension of the aqueous alkali solutions. We observed a decrease in surface tension for an increase in alkali concentration, which beyond a critical concentration forms a stable micro-emulsion. We estimate the shear viscosity of the emulsion as a function of alkali and aqueous/oil concentrations. Separately we attempt to measure the average bulk diffusion coefficient of the emulsion in both phases which is necessary to estimate the P{\'e}clet number (P{\'e}) and subsequent mass transport phenomena.