Mikael Mortensen

• Piterskaya, Anna; Miloch, Wojciech Jacek & Mortensen, Mikael (2023). A global spectral-Galerkin investigation of a Rayleigh-Taylor instability in plasma using an MHD-Boussinesq model. AIP Advances. ISSN 2158-3226. 13(10). doi: 10.1063/5.0155976. Full text in Research Archive
• Vignon, Colin; Rabault, Jean; Vasanth, Joel; Alcántara-Ávila, Francisco; Mortensen, Mikael & Vinuesa, Ricardo (2023). Effective control of two-dimensional Rayleigh-Bénard convection: Invariant multi-agent reinforcement learning is all you need. Physics of Fluids. ISSN 1070-6631. 35(6). doi: 10.1063/5.0153181. Full text in Research Archive
• Mortensen, Mikael (2023). A GENERIC AND STRICTLY BANDED SPECTRAL PETROV-GALERKIN METHOD FOR DIFFERENTIAL EQUATIONS WITH POLYNOMIAL COEFFICIENTS. SIAM Journal on Scientific Computing. ISSN 1064-8275. 45(1), p. A123–A146. doi: 10.1137/22M1492842. Full text in Research Archive
• Friedemann, Christopher; Mortensen, Mikael & Nossen, Jan (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. International Journal of Heat and Fluid Flow. ISSN 0142-727X. 88, p. 1–20. doi: 10.1016/j.ijheatfluidflow.2020.108754. Full text in Research Archive
• Marholm, Sigvald; Darian, Diako; Mortensen, Mikael; Miloch, Wojciech Jacek & Marchand, Richard (2020). A Novel Method for Circuits of Perfect Electric Conductors in Unstructured Particle-in-Cell Plasma–Object Interaction Simulations. IEEE Transactions on Plasma Science. ISSN 0093-3813. 48(8), p. 2856–2872. doi: 10.1109/TPS.2020.3010561. Full text in Research Archive
• Friedemann, Christopher; Mortensen, Mikael & Nossen, Jan (2020). Two-phase flow simulations at 0 - 4° inclination in an eccentric annulus. International Journal of Heat and Fluid Flow. ISSN 0142-727X. 83. doi: 10.1016/j.ijheatfluidflow.2020.108586. Full text in Research Archive
• Landet, Tormod; Mardal, Kent-Andre & Mortensen, Mikael (2020). Slope limiting the velocity field in a discontinuous Galerkin divergence-free two-phase flow solver. Computers & Fluids. ISSN 0045-7930. 196. doi: 10.1016/j.compfluid.2019.104322. Full text in Research Archive
• Ketcheson, David I.; Mortensen, Mikael; Parsani, Matteo & Schilling, Nathanael (2019). More efficient time integration for Fourier pseudospectral DNS of incompressible turbulence. International Journal for Numerical Methods in Fluids. ISSN 0271-2091. doi: 10.1002/fld.4773. Full text in Research Archive
• Friedemann, Christopher; Mortensen, Mikael & Nossen, Jan (2019). Gas-liquid slug flow in a horizontal concentric annulus, a comparison of numerical simulations and experimental data. International Journal of Heat and Fluid Flow. ISSN 0142-727X. 78. doi: 10.1016/j.ijheatfluidflow.2019.108437. Full text in Research Archive Show summary

  Multiphase flow simulations were run in OpenFOAM utilizing InterFoam, a volume of fluid type solver. A concentric annulus geometry was constructed and periodic boundary conditions were applied to alleviate the requirement for a longer domain. The simulations were run in 3, 5 and 7m long domains with the annulus dimensioned such that the outer and inner cylinder diameter were 0.1 and 0.05m respectively. The 4 individual mesh designs were constructed such that the coarsest mesh consists of 102k cells/m while the finest mesh was generated with 400k cells/m. Each mesh was significantly refined within 0.005m of both the inner and outer cylinder wall. The simulation data was compared with experimental pressure and holdup data collected at Institute for Energy Technology in Norway. The 3 and 7m domains reproduced slug frequencies to within 9% of the experiment results of 1.43 Hz for all mesh densities. Comparatively, the 5m domain has larger errors with respect to slugging frequency (22–27%). The 5m case performs poorly, probably due to an artificial restraint introduced by the limitation of available liquid which is set as oil = 0.53 for all cases. The αoil restriction combined with the domain length determines the amount of liquid in the system. This interaction of factors means that the domain length is an important parameter when preparing the simulation. The pressure data display a stronger dependence on the mesh quality in comparison to the slug frequency analysis. The 3m domain with a 400k cells/m mesh resulted in a maximum and minimum pressure gradient of 1783.5 and 803.9 Pa/m, compared to the experiment values of 1785 and 822 Pa/m, which are within 3% of the expected results.

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• Miloch, Wojciech Jacek; Usui, Hideyuki; Miyake, Yohei; Mortensen, Mikael; Chernyshov, A.A. & Baddeley, Lisa [Show all 11 contributors for this article] (2021). Long-term and sustainable research- based student mobility projects within space weather.

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