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Transient three-dimensional natural convection in confined fluid-saturated porous media had been investigated numerically through this work. The geometry selected is a box with time-periodic temperature variation at the vertical sides and constant wall temperature at the top and bottom. In this investigation, the momentum equation of flow through fluid-saturated porous media had been transformed to a vector potential form and solved numerically using the Successive Over Relaxation method while the energy equation is solved using the three-dimensional Alternating Direction Implicit method. The values of the Rayleigh number under investigation are (150, 200, 250 and 300). The results are presented in a form of contour maps for the temperature and a velocity vector maps for the velocity. The results reveal that the temperature within the box is increased as the time or Rayleigh number increase.The Nusselt number varies inversely with the time and directly with the Rayleigh number. Two cell convective patterns are obtained in the y-z

To cite this article: S. M. F. Hasani , M. Shakaib & M. Mahmood (2009) CFD modeling of unsteady fluid flow and mass transfer in spacer-filled membrane modules, Desalination and Water Treatment, 9:1-3, 211-220To link to this article: http://dx. A B S T R AC TThe CFD simulations in spacer-fi lled membrane modules reveal complex fl uid structure in diamond-type spacers as fl ow directional changes are seen due to inclined spacer fi laments. Despite this complex fl uid behavior the fl ow remains steady for the Reynolds number considered in this study. However, the fl ow in a parallel-type spacer earlier thought to be less complicated has shown three dimensionality as well as time dependency. Due to this transient nature, the fl ow becomes asymmetric with fl apping motion. The eddies appear immediately behind the transverse fi laments, grow in size and fi nally dissipate in the center of the fi laments. The fl ow unsteadiness also causes the shear and mass transfer rates to vary in time and major fl uctuations are seen in the center of the spacer fi laments which may be useful in the periodic removal of foulants from membrane surfaces, thus improving the process effi ciency.