Dielectrophoretic force-driven convection in annular geometry under Earth's gravity. (August 2019)

• Record Type: Journal Article
• Authors: Seelig, Torsten; Meyer, Antoine; Gerstner, Philipp; Meier, Martin; Jongmanns, Marcel; Baumann, Martin; Heuveline, Vincent; Egbers, Christoph
• Is Part Of: International journal of heat and mass transfer. Volume 139(2019)
• Page Start: 386
• Page End: 398
• Publication Date: 2019-08
• Subjects: Thermal convection -- Vertical annulus -- Cylindrical enclosures -- Thermal electro-hydrodynamic convection -- Dielectrophoretic force -- Experiments -- Flow visualisation -- Shadowgraph -- PIV -- Heat transfer; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.04.068
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Transition experimentally found from natural convection to thermal electro-hydrodynamic convection. Validation of linear stability analysis. Vertically aligned stationary columns found after first transition. Enhancement of heat transfer due to dielectrophoretic force-driven convection. Abstract: Context: A radial temperature difference together with an inhomogeneous radial electric field gradient is applied to a dielectric fluid confined in a vertical cylindrical annulus inducing thermal electro-hydrodynamic convection. Aims: Identification of the stability of the flow and hence of the line of marginal stability separating stable laminar free (natural) convection from thermal electro-hydrodynamic convection, its flow structures, pattern formation and critical parameters. Methods: Combination of different measurement techniques, namely the shadowgraph method and particle image velocimetry, as well as numerical simulation are used to qualify/quantify the flow. Results: We identify the transition from stable laminar free convection to thermal electro-hydrodynamic convective flow in a wide range of Rayleigh number and electric potential. The line of marginal stability found confirms results from linear stability analysis. The flow after first transition forms a structure of axially aligned stationary columnar modes. We experimentally confirm critical parameters resulting from linear stability analysis and we show numerically an enhancement of heat transfer.