Catálogo de publicaciones - libros

We present the results of the numerical simulation of the first stages of the melting from a side of a gallium slab by adding to the heat transfer and to the melt flow the description of the effects of the deformations of the solid phase. The experiment by Gau and Viskanta in [4] has been considered.

This work presents a dimensionless analysis of mass transport equations in fixed-bed absorbers. Focus is centered in isothermal and incompressible problems, with special attention to nonlinear adsorption and desorption processes that take place at absorbent particles. The general differential-algebraic equation system is expressed in dimensionless form, and the model is particularized into four different formulations. The model is analyzed and used to simulate a standard industrial test efficiently. Formulations are selected depending on the relative importance of the different physical phenomena involved in each part of test.

For studying the impact of a hight pressure vapor on a concrete wall, we propose a stationary 3D homogenized model. We show that the interface evolves as a (shock or rarefaction) wave accordingly with the mobility coefficient values . Moreover, we prove the existence of a finite asymptotical position for the interface when goes to +∞.

We implement a multigrid algorithm to solve the radiative heat transfer equations in glass production. The time, angle and space coordinates are discretized using Crank-Nicolson, discrete-ordinate and Galerkin methods, respectively. Based on the same mesh hierarchy for both heat conduction and radiative transfer, our multigrid algorithm consists on using the Newton-Gmres and Atkinson-Brakhage solvers as smoothers on the coarse meshes.

This paper describes the modelling of the toner behaviour in the development nip of the Océ Direct Imaging print process. The discrete element method is used as the simulation tool for a quantitative description of the system. The interaction rules and the associated parameters are determined for the toner particles and the surfaces of the development rollers. The model is validated with print quality results. It is shown that it is possible to achieve quantitative agreement between DEM simulations and experimental print quality results.

Drying in porous structures is simulated with a 2-D pore network model that accounts for various processes at the pore-scale (mass transfer by advection and diffusion in the gas phase, viscous flow in liquid and gas phases and capillary effects at the gas-liquid interface). We further study the effect of capillarity-driven viscous flow through macroscopic liquid films. It is shown that film flow is a major transport mechanism in drying of porous media, its effect being dominant when capillarity controls the process, which is the case in typical applications.

For the modelling of the glass press-blow process level set functions are used. Special difficulties arise due to velocity gradients in the domain. A reinitialisation procedure for unstructured triangular meshes is adapted to these difficulties and is applied.

The Process Plant Layout (PPL) problem involves decisions concerning the spatial allocation of equipment items and the required connections among them, [3]. The objective of the PPL problem is to determine the optimal spatial allocation of equipment items and the required connections between them. PPL problems have mostly been solved by heuristic rules but in recent years significant research effort has been put on more rigorous methods, mainly based on mathematical programming techniques. The resulting problem is often subsequently discretised in linear form and solved using linear solvers. In this paper, a non-linear approach to the general PPL problem is investigated. A comparative study between different non-linear solvers is carried out and the performance of the solvers is evaluated.

We present a simple mathematical model of fluid flow in a Scraped-Surface Heat Exchanger (SSHE). Specifically we consider steady isothermal flow of a Newtonian fluid around a periodic array of pivoted scraper blades in a channel with one stationary and one moving wall, when there is an applied pressure gradient in a direction perpendicular to the wall motion. The flow is fully three-dimensional, but decomposes naturally into a two-dimensional transverse flow driven by the boundary motion and a longitudinal pressure-driven flow.

The transmission line matrix (TLM) for simulating sound wave propagation in stationary and moving media is presented. TLM is inherently a timedomain approach which does not require solution of a differential equation. TLM and FEM are compared in terms of accuracy and computational complexity. It is concluded that TLM may represent a more efficient alternative to FEM when predicting acoustic fields in stationary media. Furthermore, applicability of TLM to moving media is examined. A TLM model of 2D moving media based on the idea of [3] is introduced.