EHD INSTABILITY OF 2 LIQUID LAYER SYSTEM WITH DEFORMABLE INTERFACE

The hydrodynamic instability of a two layer system consisting of insul ating and conducting immiscible liquids subjected to a unipolar inject ion is examined. A theoretical model taking into account the slight de formation of the interface is developed. The effect of deformation is accounted for by the Bond number and by a new non dimensional paramete r P proportional to the surface tension. The preliminary results show that, with surface deformation, the instability criterion strongly dep ends on the P number. For some values of P, two instability mechanisms bulk and interfacial ones take place. When strongly decreasing the st rength of surface tension or the liquid thickness, the critical number tends to a value such that the system is very close to interfacial in stability.