Convective heat transfer augmentation through vortex shedding in sinusoidal constricted tube

Abstract

cited By (since 1996)0International audiencePurpose - The purpose of this paper is to analyse the convective heat transfer of an unsteady pulsed, laminar, incompressible flow in axisymmetric tubes with periodic sections. The flow is supposed to be developing dynamically and thermally from the duct inlet. The wall is heated at constant and uniform temperature. Design/methodology/approach - The problem is written with classical homogeneous boundary conditions. We use a shift operator to impose non-homogeneous boundary conditions. Consequently, this method introduces source terms in the Galerkin formulation. The momentum equations and the energy equation which govern this problem are numerically solved in space by a spectral Galerkin method especially oriented to this situation. A Crank-Nicolson scheme permits the resolution in time. Findings - From the temperature field, the heat transfer phenomenon is presented, discussed and compared to those obtained in straight cylindrical pipes. This study showed the existence of zones of dead fluid that locally have a negative influence on heat transfer. Substantial modifications of the thermal convective heat transfer are highlighted at the entry and the minimum duct sections. Practical implications - Pulsated flows in axisymmetric geometries can be applied to medical industries, mechanical engineering and technological processes. Originality/value - One of the original features of this study is the choice of Chebyshev polynomials basis in both axial and radial directions for spectral methods, combined with the use of a shift operator to satisfy non-homogeneous boundary conditions. © Emerald Group Publishing Limited

Convective Heat Transfer of Unsteady Pulsed Flow in Sinusoidal Constricted Tube

“…We observe that the results are encouraging and offer good perspectives in pulsed internal flows cases. From numerical point of view, the results obtained confirm the previous general conclusions in axisymmetric geometries (André et al, 1987(André et al, , 1981Batina et al, 1989Batina et al, , 1991Batina et al, , 2009), i.e. :…”

“…The center of each vortex moves towards the downstream while moving away from the wall more and more gradually. These results perfectly agree with those previously shown by Blancher, 1991;Batina et al, 2004Batina et al, , 2009. Figure 4 shows a comparative study of the convective heat transfer by means of the Nusselt number, in stationary regime.…”

“…-Secondly, the search for particular flow conditions (transient regime, pulsed flow, etc. ): for example those linked to the periodicity of the pressure gradient (Batina, 1995;Batina et al 2009;Chakravarty & Sannigrahi, 1999;Hemida et al, 2002), or those which impose a periodic velocity condition (Lee et al, 1999;Young Kim et al, 1998) or those which carry on time periodic deformable walls. The main objective of this study is to analyse the special case of convective heat transfer of an unsteady pulsed, laminar, incompressible flow in axisymmetric tubes with periodic sections.…”

Modelling of a Phase Change Material melting process heated from below using spectral collocation methods

“…For many 2D problems, the geometry of study is a complex domain shape. For periodic geometries (Batina et al, 2009(Batina et al, , 2011, the upper and lower walls are periodic functions of the variable z. In order to deal with such geometries, we consider a general 2D-domain (D) as shown on Figure 2, with lateral edges parallel to y-axis; the two other vertical edges are defined by functions a(z) and b(z).…”

“…called collocation points: (N x þ 1) points according to the axial direction x and (N r þ 1) points according to the vertical direction r. We chose the collocation points of Chebyshev-Gauss-Lobatto (Batina et al, 2009(Batina et al, , 2011, defined by:…”