dns study by a bilayer model on the mechanism of heat transfer reduction in drag-reduced flow induced by surfactant

a bilayer model proposed in [1] is used to investigate the mechanism of heat transfer reduction of surfactant-induced drag-reducing channel flow with a constant heat flux imposed on both walls by direct numerical simulation. in the bilayer model, newtonian fluid and viscoelastic fluid are assumed to coexist with shear stress balance satisfied between the two fluid layers. a giesekus model is used to model the viscoelastic fluid induced by the addition of surfactant additives. high-order compact difference schemes are applied to discretize the convective and diffusion terms whereas minmod scheme is used to discretize the convective terms in the giesekus constitutive equations to enhance numerical stability. the effectiveness of the surfactant additives at different flow region on heat transfer reduction is investigated.