Experimental investigation of the pre–Darcy regime

The validity of Darcy’s law at very low Reynolds numbers is discussed controversially in literature, as some authors propose a pre–Darcy flow regime below some critical Reynolds number. The scope of this work is to investigate this problem experimentally. Therefore, a packing of glass spheres is perfused by different glycerin–water solutions. A linear behaviour between the flow velocity and the pressure drop through the packed spheres is found in the complete investigated range of Reynolds number Red' Re d ′ , based on the mean-pore diameter $$d'$$ d ′ and mean-pore velocity $$v'$$ v ′ with 10⁻⁹ ≤ Red' ≤ 10⁻¹ 10 - 9 ≤ Re d ′ ≤ 10 - 1 . This contradicts the results of different authors like Fand et al. (1987) or Kececioglu and Jiang (1994), postulating a pre–Darcy regime for Red' ≤ 2.8 · 10⁻⁶ Re d ′ ≤ 2.8 · 10 - 6 or Red' ≤ 0.13 Re d ′ ≤ 0.13 , respectively.