Simultaneous PIV and shadowgraph measurements of thermo-electrohydrodynamic convection in a differentially heated annulus

Abstract

Abstract Convection in a silicone oil with a temperature dependant fluid property is investigated experimentally in a differentially heated cylindrical annulus. A convective flow is induced by terrestrial gravity in axial direction and combined with an electrical tension applied between both cylinders to induce thermo-electrohydrodynamic convection. To capture the evolving velocity and temperature fields a novel combination of simultaneous PIV and shadowgraph technique is utilized. Results reveal azimuthal modes with cold and hot jets from inner and outer cylinder that are referred to the electric tension. The lack of information in the shadowgraph pictures were recovered by the PIV technique providing a deeper understanding in the nature of the development of the azimuthal mode number and the surrounding axial flow of natural convection. In addition, the results provide a robust framework in the capability of combining both techniques to investigate complex flow patterns that are non-axisymmetric.