Flow-induced deformation of a flexible thin structure as manifestation of heat transfer enhancement

Flow-induced deformation of thin flexible structures coupled with convective heat transfer has potential applications in energy harvesting and is important for understanding functioning of several biological systems. We numerically demonstrate large-scale flow-induced deformation as an effective passive heat transfer enhancement technique. An in-house, strongly-coupled fluid-structure interaction (FSI) solver is employed in which flow and structure solvers are based on sharp-interface immersed boundary and finite element method, respectively. In the present work, we validate convective heat transfer module of the in-house FSI solver against several benchmark examples of conduction and convective heat transfer including moving structure boundaries. The thermal augmentation is investigated as well as quantified for the flow-induced deformation of an elastic thin plate attached to lee side of a rigid cylinder in a heated channel laminar flow. We show that the wake vortices past the plate sweep higher sources of vorticity generated on the channel walls out into the high velocity regions - promoting the mixing of the fluid. The self-sustained motion of the plate assists in convective mixing, augmenting convection in bulk and near the walls; and thereby reducing thermal boundary layer thickness as well as improving Nusselt number at the channel walls. We quantify the thermal improvement with respect to channel flow without any bluff body and analyze the role of Reynolds number, Prandtl number and material properties of the plate in the thermal augmentation.