Autor según el artículo: Jordi Pallarés; Jna. Gavaldà; X. Ruiz

Departamento: Química Física i Inorgànica Enginyeria Mecànica

Autor/es de la URV: PALLARÉS CURTO, JORGE MARÍA; GAVALDÀ MARTÍNEZ, JOSEFA; RUIZ MARTÍ, JOSÉ JAVIER

Resumen: It is known that the cross diffusion terms generate four different types of solutions to the 11 one-dimensional unsteady diffusion equations for ternary mixtures. The stability of the 12 fluid column corresponding to these solutions can be classified depending on the sign of 13 the first derivative of density with respect to the direction of the gravity vector (i.e. 14 ⁄) and the sign of (22⁄)/, where =0 is located at the center of the 15 diffusion layer. The type of solution depends on the initial conditions and on the set of 16 diffusion coefficients considered. One type of solution corresponds to a stable fluid 17 column with (⁄<0) and (22⁄)/>0 . Two types of solutions generate fluid 18 layers with unstable density stratification (⁄>0) and the fourth type shows a fluid 19 layer with (22⁄)/<0 . We analyzed the unsteady diffusion processes in a ternary 20 mixture under the conditions of experiments carried out to determine the four diffusion 21 coefficients of the the ternary system 1,2,3,4-tetrahydronaphthaline-isobutylbenzene-22 dodecane (THN-IBB-nC12). These measurements; performed in diffusion cells with an 23 initially stable stratification within the cell, with the denser mixture at the bottom and the 24 lighter at the top; are usually based on the validity of the one-dimensional unsteady 25 diffusion mass transfer equations. The linear stability analysis for the onset of convection 26 in the unstable layers with unstable density stratification (⁄>0) indicates that the 27 critical thickness of these layers depends on the Rayleigh numbers, on the diffusion 28 2 coefficients and on the initial conditions. To illustrate the flow structures that can be 1 generated in these unstable conditions, we performed numerical simulations for selected 2 sets of diffusion coefficients at different Rayleigh numbers. The results of these 3 simulations are in general agreement with the predictions of the linear stability analysis 4 and indicate that, under specific conditions, the convective motions developed in the cell 5 produce significant departures of the concentration distributions from the pure diffusion 6 situation. 7 8

Grupo de investigación: Processat Digital de Senyals en Entorns Aeroespacials i Biomèdics Experimentació, Computació i Modelització en Mecànica de Fluids i Turbulència

Áreas temáticas: Enginyeria mecànica Ingeniería mecánica Mechanical engineering

Acceso a la licencia de uso: https://creativecommons.org/licenses/by/3.0/es/

ISSN: 0017-9310

Identificador del autor: 0000-0003-0305-2714; 0000-0001-7881-4192; 0000-0003-4020-4457

Fecha de alta del registro: 2018-03-05

Página final: 243

Volumen de revista: 106

Versión del articulo depositado: info:eu-repo/semantics/submittedVersion

Enlace a la fuente original: https://www.sciencedirect.com/science/article/pii/S0017931016309000?via%3Dihub

Programa de financiación: plan; MVI-DCMIX/ISS; ESP2014-53603-P

DOI del artículo: 10.1016/j.ijheatmasstransfer.2016.10.063

Entidad: Universitat Rovira i Virgili

Año de publicación de la revista: 2016

Página inicial: 232

Tipo de publicación: Article Artículo Article