Electrostatic Generation in Dielectric Fluids: The Viscoelectric Effect

Simultaneous energy transfer modes have been known to interact to produce unusual “coupled” effects. This coupling now has its theoretical basis in the concept of entropy production (or dissipation or irreversibility) central to nonequilibrium irreversible thermodynamics. Over the years, many examples of coupled phenomena have been identified and studied (thermoelectricity, electrokinetics, piezoelectricity, and so forth). Electrohydrodynamics (the effect of fluid motion on electric fields and the reverse effect of electric fields on fluid motion) can be explained as a thermodynamically coupled phenomenon characterized by the viscous and electrical properties of a fluid that contain mobile charges at the molecular (e.g., ions) or macroscopic (e.g., dust) levels. This is called the “viscoelectric” effect. In the first part of this paper we apply the concepts of irreversible thermodynamics to electrohydrodynamic systems to develop the relevant relationships. The second describes experiments carried out with a new type of Couette electrostatic generator. The resulting experimental data is then discussed in light of the coupled phenomenon relations previously developed.