ON THE FORCHHEIMER COEFFICIENTS FOR UNSATURATED FLOWS

The DarcyForchheimer equation is the most common model used in describing porous media flow. Many CFD pre-packaged platforms offer this model via the modified NavierStokes equations and typically implement the model under a penalization scheme. Although the theoretical basis of the Darcy-Forchheimer equation is unquestionable, its use is dependent on introduced coefficients which vary with practical applications. Despite a general range of values, the selection of these coefficients is somewhat subjective in saturated cases. For transient unsaturated flow cases, the selection of these coefficients may even be further complicated. This research experimentally investigated the inherent nature of these Darcy-Forchheimer coefficients for unsaturated flows in naturally occurring porous media. The results suggest variability of these coefficients with the transient nature of this flow regime. Thus, highlighting the invalidity of a single combination of coefficients across the entirety of unsaturated flows in natural porous media.