Design of Model Fluids for Flow Characterization Experiments Involving Mixing of Dissimilar Fluids—Refractive Index Matching and Physical Properties

Aqueous solutions of glycerol are widely used as model fluids in flow phenomena experiments. The design of these experiments involves the description of the physical properties of liquids and the refractive index matching using a salt, i.e., calcium chloride. The first part of this paper describes the physical properties of aqueous solutions of glycerol. Refractive index, viscosity, and density were measured for a mass fraction of glycerol in a range from 0 to 1 and compared to the data in the literature. In the second part, calcium chloride was added to aqueous solutions of glycerol, and the variations of density, viscosity, and refractive index with the mass fraction of calcium chloride were reported, which is a new contribution to literature. The main novelties of this work are (1) the development and validation of a set of equations to predict the rheological and physical properties of model fluids for flow studies involving dissimilar fluids; (2) the introduction of an algorithm to match the refractive index of fluids using calcium chloride. The model fluids are designed for large throughput experiments of industrial units, and low-cost solutions were considered. A Matlab script is provided that enables the easy implementation of this method in other works.