Resistance - Regime Relationship in Porous Media Flow with An Emphasis on Characteristic Length

In recent days, flow through porous medium has become a subject of great significance. Two concepts of concern are RESITANCE and REGIME of flow, the former being expressed in terms of Resistance coefficient (?) and the latter in terms of Reynolds number (Re). Both the variables are primarily dependent on characteristic length. In the case of pipe flow, ‘diameter’ is used as characteristic length to compute ? and Re. This is relatively an easier task. In porous media flow, pore size represents characteristic length. But, complex geometry of the pore system makes the task intricate to evaluate ? and Re. This paper presents the results of an experimental study on ? - Re relationship with an emphasis on characteristic length. A specially conceived permeameter with water as fluid medium and seven sizes of coarse gravel is used in the experimentation. Nineteen expressions for characteristic length are coined and a better one is proposed from the statistical analysis of experimental data. Findings are expected to add a little more to the subject of porous media flow.