Author, as appears in the article.: Pallares J; Gavaldà J; Ruiz X
Department: Química Física i Inorgànica Enginyeria Mecànica
URV's Author/s: Gavaldà Martínez, Josefa / Pallarés Curto, Jorge María / Ruiz Martí, José Javier
Keywords: Ternary systems Ternary mixtures Stable stratification Solutal convections Solutal convection Numerical simulation Numerical models Natural convection flow Natural convection Mixtures Linear stability analysis Linear stability Diffusion in liquids Diffusion coefficient Diffusion Density stratification Cross-diffusion Cross diffusion Concentration distributions Computer simulation
Abstract: It is known that the cross diffusion terms generate four different types of solutions to the one-dimensional unsteady diffusion equations for ternary mixtures. The stability of the fluid column corresponding to these solutions can be classified depending on the sign of the first derivative of density with respect to the direction of the gravity vector (i.e. ??/?y) and the sign of (?2?/?y2)/y, where y=0 is located at the center of the diffusion layer. The type of solution depends on the initial conditions and on the set of diffusion coefficients considered. One type of solution corresponds to a stable fluid column with (??/?y<0) and (?2?/?y2)/y>0. Two types of solutions generate fluid layers with unstable density stratification (??/?y>0) and the fourth type shows a fluid layer with (?2?/?y2)/y<0. We analyzed the unsteady diffusion processes in a ternary mixture under the conditions of experiments carried out to determine the four diffusion coefficients of the ternary system 1,2,3,4-tetrahydronaphthaline-isobutylbenzene-dodecane (THN-IBB-nC12). These measurements; performed in diffusion cells with an initially stable stratification within the cell, with the denser mixture at the bottom and the lighter at the top; are usually based on the validity of the one-dimensional unsteady diffusion mass transfer equations. The linear stability analysis for the onset of convection in the unstable layers with unstable density stratification (??/?y>0) indicates that the critical thickness of these layers depends on the Rayleigh numbers, on the diffusion coefficients and on the initial conditions. To illustrate the flow structures that can be generated in these unstable conditions, we performed numerical simulations for selected sets of diffusion coefficients at different Rayleigh numbers. The results of these simulations are in general agreement with the predictions of the linear stability analysis and indicate that, under specific conditions, the convective motions developed in the cell produce significant departures of the concentration distributions from the pure diffusion situation. © 2016 Elsevier Ltd
Thematic Areas: Thermodynamics Mechanics Mechanical engineering Materiais Matemática / probabilidade e estatística Interdisciplinar Geociências Fluid flow and transfer processes Engineering, mechanical Engenharias iv Engenharias iii Engenharias ii Engenharias i Condensed matter physics Ciências biológicas i Ciências ambientais Ciências agrárias i Ciência de alimentos Biotecnología Astronomia / física
licence for use: https://creativecommons.org/licenses/by/3.0/es/
Author's mail: fina.gavalda@urv.cat jordi.pallares@urv.cat josepxavier.ruiz@urv.cat
Author identifier: 0000-0001-7881-4192 0000-0003-0305-2714 0000-0003-4020-4457
Record's date: 2024-09-07
Papper version: info:eu-repo/semantics/submittedVersion
Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
Papper original source: International Journal Of Heat And Mass Transfer. 106 232-243
APA: Pallares J; Gavaldà J; Ruiz X (2017). Solutal natural convection flows in ternary mixtures. International Journal Of Heat And Mass Transfer, 106(), 232-243. DOI: 10.1016/j.ijheatmasstransfer.2016.10.063
Entity: Universitat Rovira i Virgili
Journal publication year: 2017
Publication Type: Journal Publications
Repositori URV