title: Polymer-induced change in scaling behavior in two-dimensional homogeneous turbulent thermal convection.
abstract: We study the effects of polymers in two-dimensional turbulent thermal convection using a shell model. In the absence of polymers, the inverse energy cascade in two dimensions leads to the observed Bolgiano-Obukhov scaling. When polymers are added, energy is extracted from the flow by the polymers, and as a result, the thermal balance between buoyancy and inertia in Bolgiano-Obukhov scaling is destroyed around the scales at which polymers interact strongly with the flow. This results in an increase in the Bolgiano scale and leads to a change in the scaling behavior of the velocity and temperature fluctuations for scales below the modified Bolgiano scale. We make theoretical estimates of the dependence of the mean rate of energy extracted by the polymers and the mean energy dissipation rate on the polymer relaxation time. Our theoretical analysis further leads to the prediction that the heat transport is not altered much by the polymers in two dimensions. We show that our theoretical estimates and prediction are in good agreement with the numerical results.
authors.affiliation: Dipartimento di Fisica and INFN, Università "Tor Vergata," Via della Ricerca Scientifica 1, I-00133 Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Benzi
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: Emily S C
authors.initials: ES
authors.lastname: Ching
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: C K
authors.initials: CK
authors.lastname: Wong