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: Computer simulation Concentration distributions Cross diffusion Cross-diffusion Density stratification Diffusion Diffusion coefficient Diffusion in liquids Linear stability Linear stability analysis Mixtures Natural convection Natural convection flow Numerical models Numerical simulation Solutal convection Solutal convections Stable stratification Ternary mixtures Ternary systems

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: Astronomia / física Biotecnología Ciência de alimentos Ciências agrárias i Ciências ambientais Ciências biológicas i Condensed matter physics Engenharias i Engenharias ii Engenharias iii Engenharias iv Engineering, mechanical Fluid flow and transfer processes Geociências Interdisciplinar Matemática / probabilidade e estatística Materiais Mechanical engineering Mechanics Thermodynamics

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: 2023-02-23

Papper version: info:eu-repo/semantics/submittedVersion

Link to the original source: https://www.sciencedirect.com/science/article/abs/pii/S0017931016309000

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

Licence document URL: http://repositori.urv.cat/ca/proteccio-de-dades/

Article's DOI: 10.1016/j.ijheatmasstransfer.2016.10.063

Entity: Universitat Rovira i Virgili

Journal publication year: 2017

Publication Type: Journal Publications