MACROSCOPIC MODEL OF INTERACTION BETWEEN PARTICLES IN AN ELECTRORHEOLOGICAL FLUID

The particle-particle interaction in an electrorheological fluid is in vestigated starting from the basic remark that, under DC conditions, t he electric field distribution is controlled by the conduction propert ies of both solid particles and carrying liquid. An experiment on a la rge scale model sphere of very slightly conducting material facing a m etallic plate is developed in particular by varying the even weaker bu t controlled conductivity of the surrounding liquid. The measurement o f the attraction force between sphere and plate reveals two regimes of variation of the force as a function of the applied electric field. A n approximate analysis taking into account the non-linear character of electrical conduction of the liquid at high electric fields leads to formula which fairly well account for the observed dependence on the e lectric field as well as on the ratio GAMMA of solid and liquid conduc tivities.