Natural convection from a vertical wavy surface embedded in saturated porous media

The mass-transfer coefficients have been obtained experimentally for natural convection from vertical wavy surfaces of varying amplitude-to-wavelength ratio (α/λ) when embedded in saturated porous media. The porous media were formed by randomly packing glass spheres of 3-, 4-, and 6-mm diameters. A limiting diffusion current technique based on cathodic reduction of cupric ions in acidic solution was used. The obtained data correspond to high Rayleigh numbers and exhibit non-Darcian effects. The mass-transfer coefficients from the wavy surfaces in porous media can be estimated as Sh_L* = [3.3284 - 2.4068(α/λ)](Ra_L*/ Da_L)^0.26 in the studied range of Ra_L* [(1.31 × 10⁶) - (5.56 × 10⁷)], where Ra_L* and Da_L are the modified Rayleigh and Darcy numbers, respectively.