Rayleigh-Bénard convection of Casson fluids

Mohammad Saied Aghighi (1) , Amine Ammar (2) , Christel Metivier (3) , M. Gharagozlu (1)

1 Bu-Ali Sina University
2 LAMPA - Laboratoire Angevin de Mécanique, Procédés et InnovAtion
3 LEMTA - Laboratoire d'Energétique et Mécanique Théorique et Appliquée

This study aims at investigating numerically the Rayleigh-Bénard Convection (RBC) in viscoplastic fluids. A Casson fluid is considered in a bidimensional square cavity heated from below. The effects of the dimensionless yield stress, the Bingham number Bn, on the heat transfer and motion is investigated in the range 5.10^3 < Ra < 10^5 for the Rayleigh number and Pr = 10, 100, 1000 for the Prandtl number. One shows that theyield stress has a stabilizing effect, reducing the convection intensity. Above a certain value of Bnmax , the convection does not occur and the heat transfer is only due to conduction. For moderate Bn values, truly unyielded regions are located in the center of the cavity; their areas grow with increasing Bingham number and invade the whole cavity at the threshold value Bnmax .

Mots clés: Rayleigh-Bénard; Natural convection; Yield stress; Casson model; Finite element

Domaines: Mécanique [physics.med-ph]

Mohammad Saied Aghighi, Amine Ammar, Christel Metivier, M. Gharagozlu. Rayleigh-Bénard convection of Casson fluids. International Journal of Thermal Sciences, 2018, 127, pp.79-90. ⟨10.1016/j.ijthermalsci.2018.01.016⟩. ⟨hal-02285050⟩