Gaute Linga

A thesis for the degree of Doctor of Philosophy defended October 2018.

The PhD School of Science, Faculty of  Science, Biocomplexity, Niels Bohr Institute, University of Copenhagen

Academic advisors:
 Joachim Mathiesen

Fluid Flows with Complex Interfaces: Modelling and Simulation from Pore to Pipe

In this thesis, aspects of fluid flow with disordered interfaces are investigated by numerical and theoretical means, and their relations to geophysically relevant systems are discussed.

The research output consists of physical models, numerical methods and tools, and applications of the models and methods to problems ranging from the pore to the pipe scale.

A part of the work focuses on single-phase fluid flow. In order to address the universality class of the laminar–turbulent transition in pipe flow, particle-based models for the interaction between turbulent domains are introduced. To illuminate the joint effects of a disordered geometry and fluid inertia on macroscopic transport properties, transitional flow in rough fractures is investigated by direct numerical simulations. In the limit of creeping flow, the coupling between flow and stress in dissolving porous rock is studied.

The remainder of the work concerns flows where the effects of a second phase, chemical transport, and electric fields, are included. Models for such electrohydrodynamic and two-phase flows are analysed herein. Furthermore, efficient numerical methods are developed both for single- and two-phase electrohydrodynamic flow, and a simulation framework, based on a diffuse-interface model, is introduced to facilitate simulation of phenomena including wetting at the pore scale and microfluidic devices.