Coupling of porous media flow with free flow


Doğan M. O. , Helmig R., Class H.

4th IAHR International Groundwater Symposium: Flow and Transport in Heterogeneous Subsurface Formations, Theory, Modeling and Applications. Modelling of Coupled Surface-Subsurface Processes, İstanbul, Turkey, 18 - 20 June 2008, pp.65

  • Publication Type: Conference Paper / Unpublished
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.65
  • Middle East Technical University Affiliated: No

Abstract

The numerical models of porous media are applicable for many environmental related and technical problems. Often makes the structure of the porous media the conceptual modeling difficult. Heterogeneous distribution of properties, such as permeability and porosity, causes difficulties. In particular, if a big hollow structure crosses a porous medium, porous media flow and free flow are coupled. In this case flow equations in porous media are not capable of representing the total system. Such systems are mines (shaft, pipe network), CO2 sequestration in geological formations (abandoned wells), flow of liquids and gases in fractured porous media and also oxygen and water currents in fuel cells (at the boundary of diffusion layer and gas flow field). The model calculates the flow in porous media in 2D (or 3D) and the flow in hollow structures in 1D. In porous media the velocities are calculated by using Darcy`s Law whereas in free-flow region Reynold's number is much higher than 1, i.e., Darcy's Law is not applicable. In free flow region one dimensional Navier Stokes equations are used. Cross sectional averaging of velocities and Darcy-Weisbach equation for the friction component are utilized. Although the equations in each domain are implicitly solved, the coupling is explicit. The coupling is done with the help of semi discrete semi dual-continuum concept (i.e, the domains are lying on top of each other, but the exchange term is calculated discretely). At the end of the talk, we will present few numerical studies that describe the behavior of the new approach