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DY: Fachverband Dynamik und Statistische Physik

DY 25: Fluid dynamics II

DY 25.7: Vortrag

Donnerstag, 26. März 2009, 16:15–16:30, ZEU 118

stochastic modeling of wetting effects in fluid displacement in porous media — Rafael Rangel and •Sergio Rojas — Physics Department, Universidad Simón Bolívar, Valle de Sartenejas, Edo. Miranda, Venezuela

The displacement of a viscous fluid by another that preferentially wets a porous medium is modeled with the aim to simulate a cooperative invasion processes that has been found in experiments of immiscible wetting displacement. In our model we consider the non-local effects of the Laplacian pressure field and the capillary forces. This is achieved with Diffusion Limited Aggregation DLA-type Montecarlo computations that simulate both the hydrodynamic equations in the Darcy regime with a boundary condition for the pressure at the interface. The boundary condition contains two different types of disorder: the capillary term which constitutes an additive random disorder, and a term containing an effective random surface tension which couples to a curvature (it constitutes a multiplicative random term that carries non-local information of the whole pressure). We claim that this multiplicative random disorder together with the non-local coupling causes a short range scaling regime that reveals itself in a roughness exponent α ≈ 0.80. Additionally, we find a DLA-type scaling regime with a roughness exponent α ≈ 0.60 at the largest scales. These types of scaling was found by Geromichalos, Mugele and Herminghaus [Phys.Rev.lett.89,104503(2002)]. At intermediate scales, a regime with α ≈ 0.70 has been found that has similarities with to Invasion Percolation with Trapping.