Macroscopic Equations of Motion for Two Phase Flow in Porous Media

The established macroscopic equations of motion for two phase immiscible displacement in porous media are known to be physically incomplete because they do not contain the surface tension and surface areas governing capillary phenomena. Therefore a more general system of macroscopic equations is derived here which incorporates the spatiotemporal variation of interfacial energies. These equations are based on the theory of mixtures in macroscopic continuum mechanics. They include wetting phenomena through surface tensions instead of the traditional use of capillary pressure functions. Relative permeabilities can be identified in this approach which exhibit a complex dependence on the state variables. A capillary pressure function can be identified in equilibrium which shows the qualitative saturation dependence known from experiment. In addition the new equations allow to describe the spatiotemporal changes of residual saturations during immiscible displacement.Comment: 15 pages, Phys. Rev. E (1998), in prin

Percolation thresholds in chemical disordered excitable media

The behavior of chemical waves advancing through a disordered excitable medium is investigated in terms of percolation theory and autowave properties in the framework of the light-sensitive Belousov-Zhabotinsky reaction. By controlling the number of sites with a given illumination, different percolation thresholds for propagation are observed, which depend on the relative wave transmittances of the two-state medium considered

GraphPack: Design and Features

In this paper, we describe dierent methods for three dimensional embedding of graphs, as well as a two dimensional layout method, namely barycentric embedding. In addition, we present a program for automatic recognition of graphs. We finally describe servers for graph drawing routines that can be called from C or C++ programs and applications such as Mosaic

Drawing, Manipulating, and Recognizing Graphs

In this paper, we describe different methods for three dimensional embedding of graphs, as well as a two dimensional layout method, namely barycentric embedding. In addition, we present a program for automatic recognition of graphs. We finally describe servers for graph drawing routines that can be called from C or C++ programs and applications such as Mosaic. Keywords: Graph theory, educational tool, visualization of graphs, embedding graphs, manipulating graph embeddings, recognition of graphs, client/server model. 1 Introduction GraphPack is an educational package [4] developed at Rensselaer that provides users with the capability to study and visualize graph theoretic algorithms. The graphical user interface is built on X windows. This application can manipulate both digraphs and graphs, and can draw them under different embeddings. GraphPack itself is composed of two components: the kernel and Xgraphpack. The kernel has an interpreter that accepts Lila (Little Language) commands..