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Natural convection

by Franck Pigeonneau - published on

In the industrial process, glass is made in large tank where the heat comes from above the glass bath. The large scale thermal gradients lead to natural convection in the glass bath. This kind of motion is known under the name of horizontal convection. The control parameter of the heat and mass transfer has been established in (Flesselles and Pigeonneau 2004 and Pigeonneau and Flesselles, 2011). It is equal to the product of the Rayleigh number by the aspect ratio (height over length) squared.

Open system is characterised by the residence time distribution which can be established numerically. We determine in collaboration with the Laboratoire de Génie Chimique of Toulouse the network of reactors to represent a glass furnace (see Ponsich et al., 2009).

More recently, in collaboration with the university of Florida (Depart. of Chemical Engineering), a Navier-Stokes solver has been developped based on the pseudo-spectral method. The results show that the flow in horizontal convection becomes unsteady when the Rayleigh number is lesser than a critical value. This threshold depends upon the aspect ratio (article in progress).