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Welcome to my homepage! I work as a Professor in Fluid Mechanics at the Department of Mathematics, University of Oslo. My primary interests are Computational Fluid Dynamics (CFD), scientific computing and the many aspects of turbulent fluid flows, ranging from physics, modeling, numerical methods, software implementation and applications. I spend part of my time within the 4DSpace strategic research initiative, where we study instabilities and turbulence in the polar ionosphere. I am also a Python enthusiast and I use this language as often as possible in teaching and scientific computing. Lately I have become very interested in scientific machine learning and its applications to fluid mechanics.

Recent highlights¶

• 9/6 2026 August Femtehjell defended his Master thesis: DiscoNets: Discretization-Consistent Structure-Conserving Networks

• 1/2 2026 A comparison of implicit–explicit Runge–Kutta time integration schemes in numerical solvers based on the Galerkin and Petrov–Galerkin spectral methods for two-dimensional magneto-hydrodynamic problems by Anna Piterskaya and Mikael Mortensen published by Results in Applied Mathematics

• 20/1 2026 The role of active Navier–Stokes angular momentum in identifying small-scale turbulence behavior by George Sofiadis, Mikael Mortensen, Ioannis E. Sarris and Antonios Liakopoulos published by Applied Physics Letters

• 19/3 2025 Anna Piterskaya defended her PhD thesis

• 8/9 2024 A Faster Multipole Legendre-Chebyshev Transform by Mikael Mortensen was accepted by SIAM Journal on Scientific Computing

• 10/6 2023 Effective control of two-dimensional Rayleigh--Bénard convection: invariant multi-agent reinforcement learning is all you need by Colin Vignon, Jean Rabault, Joel Vasanth, Francisco Alcántara-Ávila, Mikael Mortensen and Ricardo Vinuesa. Paper accepted for publication by Physics of Fluids.

• 30/8 2022 A generic and strictly banded spectral Petrov-Galerkin method for differential equations with polynomial coefficients by Mikael Mortensen was accepted for publication by SIAM Journal on Scientific Computing

• 21/6 2021 Japan-Norway Partnership for Computing in Space Science receives 10 MNOK in funding from the Research Council of Norway!

News¶

• 15/6 2026 17th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Kobe, Japan, with 20 Norwegian and Japanese students.

• 9/6 2026 August Femtehjell defended his Master thesis: DiscoNets: Discretization-Consistent Structure-Conserving Networks

• 13/4 2026 3rd 4DSpace School on Space Mission Data Analysis started in Kyoto, Japan, with 20 Norwegian and Japanese students.

• 1/2 2026 A comparison of implicit–explicit Runge–Kutta time integration schemes in numerical solvers based on the Galerkin and Petrov–Galerkin spectral methods for two-dimensional magneto-hydrodynamic problems by Anna Piterskaya and Mikael Mortensen published by Results in Applied Mathematics

• 20/1 2026 The role of active Navier–Stokes angular momentum in identifying small-scale turbulence behavior by George Sofiadis, Mikael Mortensen, Ioannis E. Sarris and Antonios Liakopoulos published by Applied Physics Letters

• 16/9 2025 16th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Oslo, Norway, with 20 Norwegian and Japanese students.

• 16/6 2025 15th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Kobe, Japan, with 20 Norwegian and Japanese students.

• 19/3 2025 Anna Piterskaya defended her PhD thesis

• 17/3 2025 2nd Kobe-Oslo School on Space Mission Data Analysis started in Oslo, Norway, with 20 Norwegian and Japanese students.

• 14/12 2024 Multi-agent Reinforcement Learning for the Control of Three-Dimensional Rayleigh–Bénard Convection by J Vasanth, J Rabault, F Alcantara-Avila, M Mortensen and R Vinuesa was published by Flow, Turbulence and Combustion

• 9/11 2024 A study of the Orr–Sommerfeld and induction equations by Galerkin and Petrov–Galerkin spectral methods utilizing Chebyshev polynomials by Anna Piterskaya and Mikael Mortensen was published by the Journal of Computational and Applied Mathematics.

• 16/9 2024 14th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Oslo, Norway, with 20 Norwegian and Japanese students.

• 8/9 2024 A Faster Multipole Legendre-Chebyshev Transform by Mikael Mortensen was accepted by SIAM Journal on Scientific Computing

• 24/6 2024 13th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Kobe, Japan, with 20 Norwegian and Japanese students.

• 12/6 2024 I presented Shenfun at the University of Thessaly, Greece.

• 21/4 2024 First Kobe-Oslo School on Space Mission Data Analysis started in Kyoto, Japan, with 20 Norwegian and Japanese students.

• 2/11 2023 Jacob H Hudtwalcker defended his master thesis Large Eddy Simulation of Turbulence in Helically Coiled Pipes: Effects of Mesh Strategy.

• 23/10 2023 Jacob T S Langmoen defended his master thesis Turbulent Flow Past An Edged Geometry.

• 21/10 2023 A global spectral-Galerkin investigation of a Rayleigh–Taylor instability in plasma using an MHD–Boussinesq model by Anna Piterskaya, Wojciech J Miloch and Mikael Mortensen published by AIP Advances.

• 10/6 2023 Effective control of two-dimensional Rayleigh--Bénard convection: invariant multi-agent reinforcement learning is all you need by Colin Vignon, Jean Rabault, Joel Vasanth, Francisco Alcántara-Ávila, Mikael Mortensen and Ricardo Vinuesa. Paper accepted by Physics of Fluids.

• 13/4 2023 The Japan-Norway Partnership for Computing in Space Science announced its next workshop to be held in Kobe, Japan, 17-24/6 2023

• 30/8 2022 A generic and strictly banded spectral Petrov-Galerkin method for differential equations with polynomial coefficients by Mikael Mortensen was accepted for publication by SIAM Journal on Scientific Computing

• 13/6 2022 Kei Yamamoto defended his master thesis Numerical Investigation of Turbulent Flow in Helically Coiled Pipes

• 1/6 2022 Sverre Vinje defended his master thesis Modeling the effect of slits on rowing blades

• 14/2 2022 We are back to physical teaching at the University of Oslo!

• 15/12 2021 I presented Shenfun on zoom for Prof. Haijun Yu’s research group at the Institute of Computational Mathematics and Scientific/Engineering Computing, University of the Chinese Academy of Sciences

• 21/6 2021 Japan-Norway Partnership for Computing in Space Science receives 10 MNOK in funding from the Research Council of Norway!

• 9/6 2021 Matthias Rauter defended his PhD thesis!

• 17/2 2021 Chris Friedemann defended his PhD thesis!

• 18/1 2021 Two-phase co-current flow simulations using periodic boundary conditions in horizontal, 4, 10 and 90° inclined eccentric annulus, flow prediction using a modified interFoam solver and comparison with experimental results by Friedemann C, Mortensen M and Nossen J published in International Journal of Heat and Fluid Flow.

• 10/9 2020 Trym Erik Nielsen defended his master thesis as the first cross disciplinary thesis between the physics and mathematics departments, under the 4DSpace umbrella.

• 22/8 2020 Shenfun demos are now available as executable, interactive jupyter books

• 17/8 2020 I started teaching MEK4300 - Viscous Flow and Turbulence.

• 12/8 2020 A Novel Method for Circuits of Perfect Electric Conductors in Unstructured Particle-in-Cell Plasma–Object Interaction Simulations by Marholm S, Darian D, Mortensen M, Miloch W J and Marchand R published in IEEE Transactions on Plasma Science.

• 15/6 2020 Final exam finished for my course MEK1100

• 29/5 2020 Tormod Landet defended his PhD thesis!

• 1/4 2020 Shenfun now has capability to solve equations in generic curvilinear coordinates

• 5/3 2020 Two-phase flow simulations at 0-4 degrees inclination in an eccentric annulus by Friedemann C, Mortensen M and Nossen J, accepted for publication in International Journal of Heat and Fluid Flow.

• 14/2 2020 Fast Parallel Multidimensional FFT Using Advanced MPI by Dalcin L, Mortensen M and Keyes D presented at the SIAM Workshop on Combinatorial Scientific Computing 2020.

• 31/1 2020 Sigvald Marholm defended his PhD thesis!.

• 15/1 2020 I started teaching MEK1100, an introductory course to continuum mechanics, and my first class with more than 300 students enrolled!

• 9/10 2019 Slope limiting the velocity field in a discontinuous Galerkin divergence-free two-phase flow solver by Landet T, Mardal K-A and Mortensen M, accepted for publication in Computers and Fluids

• 25/9 2019 More efficient time integration for Fourier pseudo-spectral DNS of incompressible turbulence by Ketcheson D-I, Mortensen M, Parsani M and Schilling N, accepted for publication by International Journal for Numerical Methods in Fluids

• 16/9 2019 10th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Oslo, Norway.

• 16/9 2019 Anna Piterskaya started her PhD under my supervision.

• 1/7 2019 Gas-liquid slug flow in a horizontal concentric annulus, a comparison of numerical simulations and experimental data by Friedemann C, Mortensen M and Nossen J, accepted for publication in International Journal of Heat and Fluid Flow.

• 17/6 2019 9th Kobe-Oslo workshop on numerical simulations of rocket-plasma interactions started in Kobe, Japan.

• 5/6 2019 Theory and simulations of spherical and cylindrical Langmuir probes in non-Maxwellian plasmas by Darian, Marholm, Mortensen and Miloch accepted for publication in Plasma Physics and Controlled Fusion.

• 30/5 2019 Impact of Miniaturized Fixed-Bias Multi-Needle Langmuir Probes on CubeSats by Marholm, Darian, Marchand, Miloch and Mortensen accepted for publication in IEEE Transactions in Plasma Science.

• 29/5 2019 I’m presenting Shenfun at the 11th International Conference on Scientific Computing and Applications, Xiamen, China.

• 28/5 2019 I’m teaching a 3-hour short course on Shenfun at the 11th International Conference on Scientific Computing and Applications, Xiamen, China.

• 13/5 2019 Diako Darian defended his PhD thesis!

• 8/5 2019 A demo for a coupled Navier Stokes solver for lid driven cavity published in shenfun NavierStokesDrivenCavity.py.

• 3/4 2019 mpi4py-fft: Parallel Fast Fourier Transforms with MPI for Python by M Mortensen L Dalcin and D Keyes accepted for publication in the Journal of Open Source Software.

• 2/4 2019 Tormod Landet has submitted his PhD thesis!

• 20/2 2019 Fast parallel multidimensional FFT using advanced MPI by Lisandro Dalcin, Mikael Mortensen and David E. Keyes, accepted for publication by The Journal of Parallel and Distributed Computing

• 7/3 2019 “Numerical simulations of a dust grain in a flowing magnetized plasma” by D Darian, M Mortensen, W J Miloch, H Usui and Y Miyake accepted for publication in Physics of Plasmas

• 31/1 2019 Diako Darian has submitted his PhD thesis!

• 3/1 2019 Shenfun can now be used for two non-periodic directions. It is also now possible to solve coupled equations implicitly. See Stokes demo.

• 14/12 2018 4DSpace extension approved by the faculty!

• 30/11 2018 mpi4py-fft is now available for download from the conda-forge channel.

• 20/11 2018 Shenfun: High performance spectral Galerkin computing platform by M. Mortensen, accepted for publication in the Journal of Open Source Software.

• 6/11 2018 New preprint published A Novel Method for Circuits of Perfect Electric Conductors in Unstructured Particle–In–Cell Plasma–Object Interaction Simulations by Marholm, Darian, Mortensen, Marchand and Miloch

• 6/11 2018 New preprint published Impact of Miniaturized Fixed-Bias Multi-Needle Langmuir Probes on CubeSats by Marholm, Marchand, Darian, Miloch and Mortensen

• 25/10 2018 New preprint published More efficient time integration for Fourier pseudo-spectral DNS of incompressible turbulence by Ketcheson, Mortensen, Parsani, Schilling

• 17/9 - 21/9 2018 8th 4DSpace Numerical Workshop in Oslo.

• 30/8 2018 The FDA Nozzle Benchmark: In Theory There Is No Difference Between Theory and Practice, But in Practice There Is accepted for publication in International Journal for Numerical Methods in Biomedical Engineering

• 8/8 - 10/8 2018 Christophe Henry, Post Doc at Observatoire de la Cote d’Azur, Laboratoire Lagrange is visiting for 3 days.

• 8/8 2018 Documentation for mpi4py-fft published on readthedocs

• 2/8 2018 On the Singular Neumann Problem in Linear Elasticity accepted for publication in Numerical Linear Algebra with Applications

• 6/7 2018 Particles in UNstructured Cells PUNC now openly available at github

• 2/7 2018 Dynamic ion shadows behind finite-sized objects in collisionless magnetized plasma flows accepted for publication by the New Journal of Physics

• 27/6 2018 Preconditioning trace coupled 3d-1d systems using fractional Laplacian accepted for publication by Numerical Methods for Partial Differential Equations

• 17/6 2018 7th 4DSpace Numerical Workshop in Kobe, Japan.

• 7/6 2018 Anna Piterskaya defended her master thesis Spectral investigation of annular flow

• 30/6 2018 Richard presented at SCTC’18 conference. Title Impact of miniaturized fixed-bias Multi-Needle Langmuir Probes on CubeSats, with Richard Marchand, Sigvald Marholm, Diako Darian and Wojciech Miloch

• 4/6 2018 Peter Killingstad defended his master thesis A study of dead water resistance Reynolds Averaged Navier Stokes simulations of a barge moving in stratified waters

• 1/6 2018 Karl Jacobsen defended his master thesis The dead water phenomenon - A computational fluid dynamics study

• 26/4 2018 New preprint published Fast parallel multidimensional FFT using advanced MPI by Lisandro Dalcin, Mikael Mortensen and David E. Keyes

• 25/4 2018 Submitted proposal to FRINATEK and ROMFORSKNING

• 15/2 2018 Sigvald Marholm presented a poster for the FEniCS’18 conference An Application of FEniCS: Particle–Mesh Modelling of Instruments in Ionospheric Plasma, with Richard Marchand, Sigvald Marholm, Diako Darian and Wojciech Miloch

• 19/1 2018 Anders Utnes defended his master thesis Computational Analysis of a Drag reducing Cone Grid - A finite volume simulation of the gecko’s aerodynamic skin.

• 6/11 2017 I talked at the I3MS Seminar Series of the Institute for Modeling and Simulation, RWTH Aachen University.

• 23/10 2017 I presented shenfun - automating the spectral Galerkin method at the International Conference on Computational Science and Engineering

• 20/9 2017 Wake Potential of a Dust Particle in Magnetised Plasmas, W. J. Miloch, D. Darian and M. Mortensen accepted for publication in Physica Scripta

• 18/9 2017 6th 4DSpace Numerical Workshop started in Oslo.

• 8/9 2017 Andreas Slyngstad defended his master thesis Verification and Validation of a Monolithic Fluid-Structure Interaction Solver in FEniCS.

• 14/8 2017 Numerical simulations of a sounding rocket in ionospheric plasma: effects of magnetic field on the wake formation and rocket potential. accepted for publication in the Journal of Geophysical Research: Space Physics

• 19/6 2017 5th 4DSpace Numerical Workshop started in Kobe, Japan.

• 19/6 2017 Guttorm Kvaal defended his master thesis Numerical Simulations of Pharmaceutical Particles Depositing in the Human Respiratory System.

• 15/6 2017 Jørgen Dyremyhr Tyvand defended his master thesis Computational fluid dynamics simulations of gravity wave flows

• 14/6 2017 Tormod Landet presented Slope Limiting of Divergence Free Discontinuous Galerkin Vector Fields in the Context of Two-Phase Flows at FEniCS’17

• 12/6 2017 Diako Darian presented Kinetic simulation of plasma-object interaction with FEniCS at FEniCS’17

• 29/5 2017 Sebastian Gjertsen defended his master thesis Development of a Verified and Validated Computational Framework for Fluid-Structure Interaction: Investigating Lifting Operators and Numerical Stability.

• 24/5 2017 I presented the spectralDNS project at the Predictive Complex Computational Fluid Dynamics conference at KAUST.

• 12/5 2017 I presented shenfun at MekIT’17.

• 12/5 2017 Christopher Friedemann presented his work on two-phase annulus flow at MekIT’17.

• 17/3 2017 My first academic son, Miroslav Kuchta, defended his PhD thesis with flying colors!

• 15/3 2017 A numerical investigation of intrathecal isobaric drug dispersion within the cervical subarachnoid space accepted for publication in PLOS ONE.

• 1/11 2016 Preconditioners for Saddle Point Systems with Trace Constraints Coupling 2D and 1D Domains published in SIAM Journal on Scientific Computing.