Abstract

Abstract

In this work, we present a computational approach for the numerical simulation of thermal radiation. Radiation is modeled by solving a set of two coupled partial differential equations, the so-called M1 model. A Variational Multiscale method is developed for this system, and tested on some illustrative benchmarks. The question of dealing with heterogeneous physical properties is also considered, and treated by means of an immersed method. It combines a level-set approach for representation of interfaces, mixing laws to build effective physical properties and an anisotropic mesh adaptation process, all these ingredients leading to an accurate description of the interface.

Abstract

Spallart and Allmaras [1] is a one-equation turbulence model developed for predicting complex aerodynamic flows. It will be of great interest to extend its application to predict other kind of flows in presence of heat and mass transfer. Specifically we will demonstrate, by considering two applications, that this one equation model may replace the two equation models in several heat transfer applications such as HVAC, electronics cooling and fire propagation in buildings. This will reduce computing time and numerical stiffness in CFD calculations. The first application is the 2D natural turbulent convection in a cavity differentially heated; which was considered as a benchmark case before applying CFD in any HVAC configuration. The exact configuration proposed by Ampofo [2], was then modeled and the radiation effect was studied. The second application proposed by Riera [4] was the numerical prediction of a heat exchanger based on hybrid jet impingement/micro-channel; it was used for managing high heat-flux thermal of power electronics devices. Those applications deal with low and high fluxes transfer respectively and allow demonstrating clearly the capacity of the one equation model to predict confined turbulent natural/ forced convection and jet-impingement heat transfer.

Abstract

Abstract

The focus of this paper is on the implementation and subsequent improvement of a technique for computing AC interference on buried metallic pipelines due to nearby power transmission lines. In order to perform this task, the finite element method (F.E.M.) is employed. After performing a description of the implementation of the classic F.E.M. approach, a hybrid technique designed to reduce the size of the mesh and therefore the computational time is presented. The results obtained with the two approaches are finally compared.

Abstract

Abstract