Experimental investigation of inertial flow processes in porous media (original) (raw)

2009, Journal of Hydrology

s u m m a r y 23 The hydraulic behavior of inertial flows in porous media is experimentally investigated. A vertical metal 24 column was constructed, of dimensions 0.5 m in diameter and 2.30 m in height. Eight different porous 25 media were used in the experiments. Head loss was measured. A total of 454 experimental data were col-26 lected. The experimental data indicate that, for a wide spectrum of velocities, both the Forchheimer and 27 Izbash equations offer excellent descriptions of the flow processes. For moderate values of the Reynolds 28 number, a discontinuity in the velocity-hydraulic gradient curve was detected, a behavior also predicted 29 by former numerical studies. The analysis of the hydraulic behavior of bidisperse media indicate the 30 influence of wall effects taking place at the interface between small and large grains. The data are used 31 to validate semi-empirical relations, and give also some insight on the flow processes taking place at the 32 pore-scale for the case of non-Darcian flows. 33 Ó 2009 Published by Elsevier B.V. 34 35 36 Introduction 37 In most studies examining flow processes in groundwater, it is 38 assumed that flow is described by the linear Darcy's law; standard 39 software and theoretical descriptions are based on this assumption 40 (McDonald and Harbaugh, 1988; Bear, 1979). 41 As problems involving flow and transport processes in coarse 42 porous media and fractures emerged, an adequate description of 43 these processes became crucial. Therefore, recently, a substantial 44 research effort is focused on ''non-conventional" groundwater prob-45 lems, including coupled flow and transport processes in individual 46 fractures or fracture networks, and inertial flows in groundwater. 47 High-velocity flows in underground geological formations occur in 48 many real-world problems, including the exploitation of hot dry 49 rock formations (Kohl et al., 1997), simulation of pollutant transport 50 in waste rock deposits (Greenly and Joy, 1996), and water extraction 51 issues (Wen et al., 2006, 2008a,b; Mathias et al., 2008), while other 52 applications include design of constructed wetlands (Economopou-53 lou and Tsihrintzis, 2003; Akratos and Tsihrintzis, 2007). 54 For both coarse porous media and fractures, this type of flow 55 can be adequately described either by the Forchheimer or the Iz-56 bash law . For the 57 one-dimensional case, these equations read, respectively: