Mikael Mortensen

• Bergersen, Aslak W.; Mortensen, Mikael & Valen Sendstad, Kristian (2019). The FDA nozzle benchmark: “In theory there is no difference between theory and practice, but in practice there is”. International Journal for Numerical Methods in Biomedical Engineering.  ISSN 2040-7939.  35(1) . doi: 10.1002/cnm.3150
• Dalcin, Lisandro; Mortensen, Mikael & Keyes, David (2019). Fast parallel multidimensional FFT using advanced MPI. Journal of Parallel and Distributed Computing.  ISSN 0743-7315.  128, s 137- 150 . doi: 10.1016/j.jpdc.2019.02.006
• Darian, Diako; Marholm, Sigvald; Mortensen, Mikael & Miloch, Wojciech Jacek (2019). Theory and simulations of spherical and cylindrical Langmuir probes in non-Maxwellian plasmas. Plasma Physics and Controlled Fusion.  ISSN 0741-3335.  61(8) . doi: 10.1088/1361-6587/ab27ff
• Darian, Diako; Miloch, Wojciech Jacek; Mortensen, Mikael; Miyake, Yohei & Usui, Hideyuki (2019). Numerical simulations of a dust grain in a flowing magnetized plasma. Physics of Plasmas.  ISSN 1070-664X.  26(043701), s 1- 14 . doi: 10.1063/1.5089631
• 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.

• 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
• Kuchta, Miroslav; Mardal, Kent-Andre & Mortensen, Mikael (2019). On the singular Neumann problem in linear elasticity. Numerical Linear Algebra with Applications.  ISSN 1070-5325.  26(1) . doi: 10.1002/nla.2212
• Kuchta, Miroslav; Mardal, Kent-Andre & Mortensen, Mikael (2019). Preconditioning trace coupled 3d-1d systems using fractional Laplacian. Numerical Methods for Partial Differential Equations.  ISSN 0749-159X.  35(1), s 375- 393 . doi: 10.1002/num.22304
• Marholm, Sigvald; Marchand, Richard; Darian, Diako; Miloch, Wojciech Jacek & Mortensen, Mikael (2019). Impact of Miniaturized Fixed-Bias Multineedle Langmuir Probes on CubeSats. IEEE Transactions on Plasma Science.  ISSN 0093-3813.  47(8), s 3658- 3666 . doi: 10.1109/TPS.2019.2915810 Full text in Research Archive.
• Mortensen, Mikael; Dalcin, Lisandro & Keyes, David (2019). mpi4py-fft: Parallel Fast Fourier Transforms with MPI for Python. Journal of Open Source Software (JOSS).  ISSN 2475-9066.  4(36) . doi: 10.21105/joss.01340

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