Validation of direct pore scale modeling approaches to wettability

Validation of direct pore scale modeling approaches to wettability

Raul Verma, Matteo Icardi, Masa Prodanovic, Validation of direct pore scale modeling approaches to wettability, submitted March 2015
Raul Verma, Matteo Icardi, Masa Prodanovic
Validation of direct pore scale modeling approaches to wettability
2015
Understanding of pore-scale physics  for multiphase  flow in porous media is essential for accurate description of various  flow phenomena.  In particular, capillarity and  wettability strongly  influence  capillary pressure-saturation and relative permeability relationships. Wettability is quantified  by the con- tact  angle of the fluid-fluid interface  at the pore walls.  In this work we com- pare the interface  capturing  method implemented  in a popular  open-source finite volume  computational fluid dynamics  solver  with a new formulation of the level set method that models capillarity-dominated flow and is less computationally expensive.  The methods  fundamentally differ in the way they  mesh porous  geometry  and capture  interfaces,  as well as in the num- ber of equations  solved  and other  implementation and algorithmic  details. Both methods  are able  to solve  curvature-driven flow and implement  arbi- trary  contact  angles  at  pore walls.   The methods  are tested  in rhomboidal packings  of spheres  for a  range  of contact  angles  and  for different  rhom- boidal configurations. Predictions are validated against  the semi-analytical solutions  obtained  by Mason and Morrow (1994).  We specifically focus on evaluating the accuracy of each method (algebraic VOF and level-set)  and benefits and limitations  of employing a less computationally intense method for semi-equilibrium  capillary-dominated flows vs.   the  full approximation of the Navier-Stokes  equation  applicable also to inertial  and viscous  flows. Consequences for larger  and more complex  problems  are also considered.