Experimental Methods

The tip streaming of simple fluids is affected by the densities and viscosities of the phases involved in the phenomenon, as well as by the surface tensions of the interfaces formed between them. In addition, electrical conductivities and permittivities are essential when electrohydrodynamic forces drive this phenomenon. As explained in Chap.  1 , complex fluids are referred to as those including surfactant molecules and polymer chains. The tip streaming of these fluids involves additional physical properties that must be known to analyze the phenomenon. The first section of this chapter describes the experimental techniques commonly used to characterize complex fluids for studying tip streaming. The analysis of the tip streaming flow relies on visualization techniques in practically all the experiments. The method most frequently used for this purpose is the observation of the interface contour, in many cases using high-speed imaging. The last section of this chapter reviews the most relevant aspects of this methodology. We also briefly describe some specific characteristics of particle image velocimetry.