I am a PhD candidate at NTNU. My project is entitled "Mathematical modelling of two-phase flows and heat transfer in confined geometries". It was initiated 1 September 2010 and should last until 31 August 2013.

### General

The main objective of my PhD project is to develop fundamental knowledge of two-phase flow phenomena relevant for heat exchangers, and thus LNG-process plants. Such flow phenomena include droplet-film interactions, flows in tubes and manifolds, and flows across tubes. The basic hypothesis is that a greater understanding of the fundamental phenomena may lead to more efficient processes with lower energy consumption and reduced downtime.

My objectives can be summarized as follows:

• Develop a mathematical model formulation for calculating two-phase flow in geometries that are relevant for heat exchangers.
• Implement the mathematical model in a numerical code.
• Verify the implementation with simulations of simple test cases.
• Perform numerical simulations on physically relevant cases.
• Analyse the results of the simulations in step 4 and compare them with experimental results.
A more detailed description of my project can be found here.

### Research stay at UCI

As part of the PhD project I visited Professor John Lowengrub at the University of California - Irvine. The main objective of the stay was to focus my research on methods for handling two-phase flows in complex domains. In particular, I studied the diffuse-domain approach, where complex domains are handled implicitly with the use of continuous approximations of the Heaviside function and the delta function.

## List of publications

Curvature calculations for the level-set method.
K. Y. Lervåg and Å. Ervik.
In: ENUMATH 2011 proceedings volume, Springer. ISBN: 978-3642331336. Preprint.

Calculation of interface curvature with the level-set method.
K. Y. Lervåg.
In: MekIT'11 - 6th National Conference on Computational Mechanics. ISBN 978-82-519-2798-7. Preprint.

Sharp interface simulations of surfactant-covered drops in electric fields.
K. E. Teigen, K. Y. Lervåg and S. T. Munkejord.
In: Fifth European Conference on Computational Fluid Dynamics, ECCOMAS CFD 2010. ISBN 978-989-96778-1-4. Preprint.

Calculation of droplets impinging on a plane surface: Accurate calculations of interfacial curvature with the level-set method.
K. Y. Lervåg, K. E. Teigen and S. T. Munkejord.
In: First Trondheim Gas Technology Conference, 21-22 October 2009. Presentation.