Flow rate depends upon the viscosity. If the solution has less viscosity, it can flow easily into the medium. Another fact, the viscosity is inversely proportional to temperature. Emulsion may be have higher viscosity than biodiesel. Biodisel able to help to reduce emulsion viscosity. at the same time, the ratio of biodiesel and emulsion is very important. Biodisel proportion is high, it can favorable to flow in emulsion medium.
temperature, ratio of biodiesel & emulsion and viscosity, these are important factors.
Since the biodiesel is methyl ester compounds, has a lower viscosity than oil. So it add to the emulsion oil, will reduce viscosity probably. Also The initial viscosity of oil and water emulsions dependent on the oil to water ratio.