Liquid flow through sands: reliability of tortuosity measured from electrical conductivity and the importance of evaluating effective porosity
Résumé
Sand beds are commonly used in many industrial applications, mainly as a filtering medium, and in civil engineering. However, predicting the pressure drop of liquid flow through sand beds with simple models remains elusive. Among the many factors that explain this failure is the difficulty of determining tortuosity and effective bed porosity. This work investigates the experimental determination of hydraulic tortuosity of different natural sands from electrical conductivity. Different protocols are tested and discussed. They underline the importance of a proper determination of effective porosity, i.e., the fraction of bed volume concerned by fluid flow. Correct determination of the effective porosity may help to reconcile actual bed parameters with those determined from pressure data using a capillary-type flow model.