Disputation: Christopher Friedemann

Doctoral candidate Christopher Friedemann at the Department of Mathematics, Faculty of Mathematics and Natural Sciences, is  defending the thesis Simulations of two-phase gas-liquid flow in concentric and eccentric annuli at 0 to 90 degrees inclination using the volume of fluid method for the degree of Philosophiae Doctor.

Picture of the candidate.

Doctoral candidate Christopher Friedemann

The University of Oslo is closed. The PhD defence and trial lecture will therefore be digital and streamed directly using Zoom. The host of the session will moderate the technicalities while the chair of the defence will moderate the disputation.

Ex auditorio questions: the chair of the defence will invite the audience to ask questions ex auditorio at the end of the defence. If you would like to ask a question, click 'Raise hand' and wait to be unmuted.

Trial lecture

Prerecorded trial lecture

"Are numerical simulations more reliable than experiments for complex multiphase flows? How can we know and compare?"

Prerecorded trial lecture

Main research findings

Unfortunate incidents related to the subsea oil and gas industry, such as leaks, can disturb and endanger large eco-systems and severely impact bio-habitats' long-term viability. There are several ways in which oil and gas could escape a subsea pipeline, one of which is a burst of a transport pipeline. In this work, I study how oil and gas behave in conjunction with an annular pipeline.

To better understand and predict fluid flow interactions between multiple liquids and gases, detailed studies, both experimentally and computationally, are needed to establish a prediction model framework. Prediction models for the behavior of two or more phases are generally developed based on large data sets collected in a lab; therefore, the models are limited to the same conditions.

The most prominent aspects studied in this thesis were the pressure gradient that occurs inside the pipeline and the frequency of flow structures. Flow structures, such as waves and slugs, which are liquid bodies that cover the cross-sectional area of the pipe, affect the pressure gradient and produce a periodic loading on the pipeline, which may contribute to fatigue.


Adjudication committee


  • Professor Mikael Mortensen, University of Oslo
  • Chief Scientist Jan Nossen, Institute for Energy Technology
  • Senior researcher Murat Tutkun, Institute for Energy Technology

Chair of defence

  • Head of Department Geir Dahl, University of Oslo

Host of the session

Professor Atle Jensen, University of Oslo

Published Feb. 17, 2021 2:24 PM - Last modified Apr. 21, 2021 12:26 PM