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Journal of Porous Media
Facteur d'impact: 1.49 Facteur d'impact sur 5 ans: 1.159 SJR: 0.43 SNIP: 0.671 CiteScore™: 1.58

ISSN Imprimer: 1091-028X
ISSN En ligne: 1934-0508

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Journal of Porous Media

DOI: 10.1615/JPorMedia.v18.i4.10
pages 369-378

THE ONSET OF TRANSIENT SORET-DRIVEN BUOYANCY CONVECTION IN NANOPARTICLE SUSPENSIONS WITH PARTICLE-CONCENTRATION-DEPENDENT VISCOSITY IN A POROUS MEDIUM

Dhananjay Yadav
University of Nizwa, Oman
MinChan Kim
jeju national university

RÉSUMÉ

The onset of transient Soret-driven convection in a horizontal layer of a porous medium saturated by a fluid with nanoparticles suspensions, which is heated from above, is studied where the viscosity depends on the local concentration of nanoparticles of practical importance. For the case of high solutal Darcy-Rayleigh number RsD with a large negative Soret coefficient DT, the applied even small temperature on the upper boundary creates Soret diffusion and then the convective motion occurs during the transient diffusion stage. In conjunction with the Soret diffusion, the nanoparticle concentration becomes stratified as given by Eq. (22), and hence the viscosity is stratified. The nanofluid is considered to be dilute, i.e., the volume concentrations of nanoparticles is very small 0.01%−2.0%, and this permits the porous medium to be taken as a weakly heterogeneous medium with variation in the vertical direction of viscosity. In turn this allows an approximate analytical solution to be obtained using a spectral method. The critical times of the onset of this Soret-driven convection are obtained as a function of the modified solute Rayleigh-Darcy number Rs*D for different values of viscosity variation parameter Q. Decreasing Q can enhanced these times Q. The results from theory are also compared with the experimental results. We show that the results from the theoretical predictions are too close to explain the experimental work.