A model of hairy medium is developed using a homogenized approach, and the fluid flow around a circular cylinder partially coated with hair is analysed by means of numerical simulations. The capability of this coating to adapt to the surrounding flow is investigated, and its benefits are discussed in the context of separation control. This fluid–structure interaction problem is solved with a partitioned approach, based on the direct resolution of the Navier–Stokes equations together with a nonlinear set of equations describing the dynamics of the coating. A volume force, arising from the presence of a cluster of hair, provides the link between the fluid and the structure problems. For the structure part, a subset of reference elements approximates the whole layer. The dynamics of these elements is governed by a set of equations based on the inertia, elasticity, interaction and losses effects of articulated rods. The configuration chosen is that of the two-dimensional flow past a circular cylinder at Re=200, a simple and well-documented test case. Aerodynamics performances quantified by the Strouhal number, the drag and the maximum lift in the laminar unsteady regime are modified by the presence of the coating. A set of parameters corresponding to a realistic coating (length of elements, porosity, rigidity) is found, yielding an average drag reduction of 15% and a decrease of lift fluctuations by about 40%, associated to a stabilization of the wake

Abstract:The overall efficiency of a regenerative chamber for a glass furnace mainly relies on the thermo-fluid dynamics of air and waste gas alternatively flowing through stacks of refractory bricks (checkers) determining the heat recovery. A numerical approach could effectively support the design strategies in order to achieve a deeper understanding of the current technology and hopefully suggest new perspectives of improvement. A computational fluid dynamics (CFD) scheme for the regenerator is proposed, where the real geometry of the solid phase is modelled as a porous solid phase exchanging heat with the gas stream. Satisfactory data fitting proved the reliability of the present approach, whose applications are proposed in the last section of this study, to confirm how such a CFD modelling could be helpful in improving the overall energy efficiency of the regeneration chamber.

Cutaneous collagenous vasculopathy (CCV) is a rare idiopathic microangiopathy of the cutaneous vasculature characterized histologically by the presence of dilated small blood vessels with flat endothelial cells and thickened walls containing hyaline material in the upper dermis. We report an elderly patient presenting with an extensive form of CCV involving the trunk, upper and lower limbs. She was treated with Multiplex PDL 595-nm/Nd:YAG 1,064-nm laser and optimized pulsed light. This approach, which has never been reported for CCV so far, resulted in a striking and almost complete clearance of the widespread lesions. We here review our knowledge about CCV and therapeutic options available with a survey of the literature.

No abstract