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 Re_d' , based on the mean-pore diameter d' and mean-pore velocity v' with 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 Re_d'≤ 2.8 · 10^-6 or Re_d'≤ 0.13 , respectively. Graphical abstract