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Associate Professor Mikael Mortensen |
| Email: | mikaem at math.uio.no |
| Mobile Phone: | +47 41407201 |
| Work Phone: | +47 22855866 |
| Visiting Address: | Niels Henrik Abels hus, Moltke Moes vei 35, 0851 OSLO, Norway |
| Postal Address: | Postboks 1053 Blindern, 0316 OSLO, Norway |
BackgroundI currently work as an Associate Professor in Fluid Mechanics at the Department of Mathematics, University of Oslo. I also hold a 20% position as adjunct research scientist at Simula Research Laboratory at the Center for Biomedical Computing. My primary interests are Computational Fluid Dynamics (CFD) and the many aspects of turbulent fluid flows, ranging from physics, modeling, numerical methods, software implementation and applications. I received my PhD thesis in chemical engineering from Chalmers University of Technology in 2005. My thesis revolved around mathematical modelling of turbulent mixing and reacting flows. I have worked mostly with the Conditional Moment Closure (CMC), a state-of-the-art model that is used to capture turbulence-chemistry interactions for mixing sensitive chemical reactions, like in non-premixed turbulent combustion. From 2005-2006 I had the great honour of working with Prof. Robert W. Bilger as a Post Doctoral research fellow at the University of Sydney, Australia. In Sydney I worked on CMC for spray combustion and a version of my consistent turbulent mixing model that I have called the presumed mapping function approach. The presumed mapping functions have been implemented in the open source package PMFpack, available under a GNU Lesser General Public License. After Sydney and before I arrived at UiO I spent 5 years at the Norwegian Defence Research Establishment (FFI), where I was involved in applied CFD research projects covering a broad range of physics - from aerosol transport and boundary layers to fighter jet aircrafts and biomedical flows. A comprehensive list of my citations and papers can be viewed on google scholar.
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I currently prefer devloping solvers through the FEniCS project. FEniCS is a collection of free software with an extensive list of features for automated, efficient solution of differential equations. Using FEniCS and its high-level Python interface I am working on CBC.PDESys, a framework for solving large systems of Partial Differential Equations, often encountered in CFD of turbulent flows. CBC.PDESys is also featured here. Using CBC.PDESys I can write a Navier-Stokes solver in less than 50 lines of code - and it will run in parallel with no additional effort. Using a few hundred lines of code and the solver runs as fast as the best competing finite volume Navier-Stokes solvers out there. The figure of the turbulent channel flow is featuring a CBC.PDESys calculation of a small 1003 box that is running on my laptop computer. The same code has recently been tested and scales well on hundreds of cores on the Abel supercomputer.
CBC.PDESys has also been used to compute nonlinear Reynolds Averaged Navier Stokes equations using a range of different eddy viscosity and Reynolds stress models.
- Spalart-Allmaras
- Standard k-epsilon
- Low-Reynolds k-epsilon (3 different)
- Menter’s SST
- V2F standard
- V2F Lien-Kalizin
- Standard
- Elliptic relaxation
Most notably, the elliptic relaxation model is a Reynolds stress model consisting of, amongst other things, two coupled nonlinear second rank tensor Partial Differential Equations. Using CBC.PDESys it is trivial to implicitly couple and solve these two tensor equations, which is a major advantage for stable and efficient implementations. A tutorial cbc.rans-MekIT11.pdf on using CBC.PDESys to implement advanced turbulence models was published in the proceedings of the 6th National Conference on Computational Mechanics, 2011 (MekIT‘11). More information can be found in the recently published paper A FEniCS-Based Programming Framework for Modeling Turbulent Flow by the Reynolds-Averaged Navier-Stokes Equations (Advances in Water Resources, 2011, DOI: 10.1016/j.advwatres.2011.02.013).