FLUID FLOW THROUGH POROUS MEDIA IN A CENTRIFUGAL FIELD

There is growing interest in the application of centrifuge techniques to the investigation of flow and transport in variably saturated porous and fractured media. This interest arises largely from the increased driving force for unsaturated flow using the centrifuge and the potential for completing relevant vadose zone experiments in less time than that required when using conventional 1-gravity techniques. To fully realize the potential of centrifuge experimental approaches, equations of fluid flow in a variable centrifugal field have been derived and are compared to equations in a constant 1-gravity field. We have derived an expression for fluid potential under conditions where centripetal and gravitational accelerations are significant. In addition, we show from the Navier-Stokes equations applied to porous media flows within a geocentrifuge the relative effects that a variable gravity field, represented by the centripetal force and the coriolis force, have on the flow fields. Nondimensionalization of the governing equations shows the role that the Ekman and Rossby numbers play in these porous media flows. This analysis provides information useful for the scaling of variable gravity geocentrifuge experiments and helps to define the theoretical limits under which geocentrifuge experiments exhibit similarity to field phenomena.