Coupling of porous media flow with pipe flow


Doğan M. O.

Eigenverlag des Instituts für Wasserbau, Stuttgart, 2011

  • Publication Type: Book / Research Book
  • Publication Date: 2011
  • Publisher: Eigenverlag des Instituts für Wasserbau
  • City: Stuttgart

Abstract

Many flow problems in environmental, technical and biological systems are characterized

by a distinct interaction between a flow region in porous medium and a free flow region in

quasi-one-dimensional hollow structures. Examples for such systems are:

 Mines: Methane released from unmined coal seams migrates through the porous

rocks, but also through tunnels and shafts in the mine.

 Landslides: A sudden water infiltration through macro-pores may trigger landslides.

 Polymer electrolyte membrane fuel cells: The supply of reactive gases through free-flow

channels into the porous diffusion layers interacts strongly with the evacuation

process of the water, which is formed at the cathode reaction layer and flows from the

porous diffusion layers into the free-flow channels .

 Cancer therapy: Therapeutic agents are delivered via the blood vessels into the tissue,

targeting the tumor cells.

The goal of this study is to introduce new coupling strategies and to develop coupled numerical

models which can form a basis for further studies modeling the complex systems

mentioned above.

In this study, different model concepts based on a dual-continuum strategy for the simulation

of coupled porous media flow with lower-dimensional pipe flow are further developed

and tested. For the numerical implementation a special grid called 1D pipe network grid in

a 3D porous grid is developed.

The dual-continuum concept is extended for coupling multi-phase porous media flow with

lower-dimensional single-phase pipe flow. The complexity of the considered flow regimes

is increased gradually. Examples are given for a coupled single-phase incompressible and

compressible flow in both porous media and pipe flow domains. The single-phase coupling

strategy is tested by comparing the results with results of the experiment done in controlled

laboratory conditions. Furthermore, the coupling of single-phase pipe flow with a multiphase

flow based on Richards equation for the unsaturated soil zone is modeled, where the

important role of capillary effects for the mass exchange rate between the two continua can

be illustrated. The next model introduces a concept for a two-phase porous media flow coupled

with a single-phase (gas) pipe flow problem, which reveals that the mobility exchange

term can be decisive for the mass exchange rate. The final model presents a concept for

coupling two-phase two-component porous media flow with single-phase two-component

pipe flow. This model is able to simulate more complicated transport systems by accounting

not only for the mobility exchange term but also for the concentrations of the exchanged

components between the continua. It is shown that the concentration of the components in

each continua play a significant role for the compositional ratio of the exchanged mass.