Gunilla Efraimsson, Associate Professor, Docent

Contact

Phone: +46-8-790 64 31
Mobile: +46-70-251 07 00
E-mail: gef@kth.se

Courses

SD2625 Computational Vehicle Aerodynamics

Education

• Ph.D., Numerical Analysis, Royal Institute of Technology, 1998
• Tech. Lic., Numerical Analysis, Royal Institute of Technology, 1993
• Master of Science, Engineering Physics, Uppsala University of Technology, 1991

Research Interest

• Aeroacoustics: Numerical simulation of generation and propagation of sound with the use of higher order accurate methods.
• Vehicle aerodynamics: Simulation of aerodynamics for trains, buses and cars using CFD.
• Numerical analysis: Development and analysis of shock capturing schemes and non-reflecting boundary conditions.

Graduate Students

Romain Futrzynski

Oscar Kårekull

Tomas Muld

Anders Rynell

Maximilian Tomac

Publications

O'Reilly C, Alenius E, Efraimsson G and Bodony D, Aero-acoustic Simulations of an Orifice in a Low-Mach-Number Ducted Flow, AIAA-paper 2012-2293, 18th AIAA/CEAS Aeroacoustics conference, 4-6 June 2012, Colorado Springs, USA, 2012

Kierkegaard A., Åbom M. and Efraimsson G. Frequency-Domain Linearized Navier-Stokes Equations for Flow-Duct Compuational Aeroacoustics,  NOVEM 2012, 1-4 April, Sorrento, 2012 

Muld T.W, Efraimsson G., Henningson D. S,Flow Structures around a High-Speed Train extracted using Proper Orthogonal Decomposition and Dynamic Mode Decomposition, Computers and Fluids, DOI: 10.1016/j.compfluid.2011.12.012, 2012

Kierkegaard A., Boij S. and Efraimsson G., Simulations of the scattering of sound waves at a sudden area expansion, Journal of Sound and Vibration, 2011, doi:10.1016/j.jsv.2011.09.011

O'Reilly C,  Alenius E., Efraimsson G., Bodony D., Numerical simulation of flow-induced sound generation from an orifice in a low Mach number ducted flow, AIAA-2011-2894
17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, Oregon, June 5-8, 2011

Kierkegaard A., Efraimsson G.,  Simulations of Duct Whistling with Nyquist Analysis and Linearized Navier-Stokes equations, AIAA-2011-2893, 17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), Portland, Oregon, June 5-8, 2011

Muld T.W, Efraimsson G., Henningson D. S,  Mode decomposition on surface mounted cube, Flow, Turbulence and Combustion, DOI: 10.1007/s10494-011-9355-y, 2011

Favre T., Efraimsson G., An Assessment of Detached-Eddy Simulations of Unsteady Crosswind Aerodynamics of Road Vehicles Flow, Turbulence and Combustion, Vol 87(1), pp 133-163, 2011

Muld T. W., Efraimsson G., Henningson D. S., Herbst A. H. and Orellano A., Analysis of Flow Structures
in theWake of a High-Speed Train, Aerodynamics of Heavy Vehicles III: Trucks, Buses and Trains,
September 12-17, 2010, Potsdam, Germany

Favre T, Efraimsson G, Numerical study of design alterations affecting the crosswind characteristics of a generic road vehicle model, 8th MIRA International Vehicle Aerodynamics Conference, 13-14 Oct, 2010

Kierkegaard A., Efraimsson G., Simulations of acoustic scattering in duct systems with flow, Proceedings of 20th International Congress on Acoustics, ICA 2010, 23–27 August 2010, Sydney, Australia

Favre T., Efraimsson G, Detached-Eddy Simulations of the Effects of Different Wind Gust Models on the Unsteady Aerodynamics of Road Vehicles, FEDSM-ICNMM2010-30454, Proceedings of the ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting & 8th International Conference on Nanochannels, Microchannels, and Minichannels FEDSM-ICNMM 2010, August 1 - 5, 2010, Montreal, Quebec, Canada

Kierkegaard A., Efraimsson G., A Study of Interpolation Accuracy in Acoustic Analogy Integrals AIAA-2010-3997, 16th AIAA/CEAS Aeroacoustic conference, 2010.

Efraimsson G., Forsberg N, Nordstrom J. Simulations of Acoustic Waves in a Turbo-Fan Engine Air Intake, AIAA-2010-3999, 16th AIAA/CEAS Aeroacoustic conference, 2010.

Kierkegaard A., Efraimsson G, Boij S, Abom M, Simulations of the whistling potentiality of an in-duct orifice with linear aeroacoustics, AIAA-2010-4008, 16th AIAA/CEAS Aeroacoustic conference, 2010.

Kierkegaard, A., Boij S., Efraimsson G., A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges, J. Acoust. Soc. Am. Volume 127,Issue 2, pp. 710-719 , 2010.

Kierkegaard, A., Åkervik, E., Efraimsson, G. & Henningson D.S. 2010, Flow field eigenmode decompositions in aeroacoustics, Computers & Fluids 39(2), 338-344, 2010

Favre T., Diedrichs B. and Efraimsson G., Detached-Eddy Simulations applied to Unsteady Crosswind Aerodynamics of Ground Vehicles, In Progress in Hybrid RANS-LES Modelling Papers Contributed to the 3rd Symposium on Hybrid RANS-LES Methods, Gdansk, Poland, June 2009 Series: Notes on Numerical Fluid Mechanics and Multidisciplinary Design, Vol. 111 Peng, Shia-Hui; Doerffer, Piotr; Haase, Werner (Eds.), 1st Edition, 2010, ISBN: 978-3-642-14167-6

Efraimsson G., Kreiss G., Analysis of Stretched Grids as Buffer Zones in Aero-acoustic Simulations, AIAA-2009-3113, 15th AIAA/CEAS Aeroacoustic conference, 11-13 May, 2009

Muld T. W., Efraimsson G., Henningson D. S., Herbst A. H., Orellano A., Detached Eddy Simulation and Validation on the Aerodynamic Train Model, Euromech Colloquim 509, Vehicle Aerodynamics, Berlin Germany, March 24-25 2009

Kierkegaard A, Boij S., Efraimsson G., Scattering matrix evaluation with CFD in low Mach number flow ducts, SAE paper 2009-01-2040, 2009.

Muld T. W., Efraimsson G., Henningson D. S., Proper Orthogonal Decomposition of Flow Structures around a Surface-mounted Cube Computed with Detached-Eddy Simulation, SAE paper 09B-0170, 2009

Favre T., Efraimsson G. and Diedrichs B., Numerical Investigation of Unsteady Crosswind Vehicle Aerodynamics using Time-Dependent Inflow Conditions, 7th MIRA International Vehicle Aerodynamics Conference, 22-23 Oct, 2008

Kierkegaard A., Efraimsson G., Acoustic propagation in a flow duct with an orifice, International Conference on Noise and Vibration Engineering, 15-17 Sep, 2008.

Stensson Trigell A., Berg M., Boij S., Efraimsson G., Jerrelind J., Wennhage P. and Göransson P., ECO2 Vehicle Design – an initiative for a holistic perspective on future vehicle concepts, Transport Research Arena Europe 2008, Ljubljana, Slovenia, 2008.

Efraimsson G., Pieper T., Åbom M., and Boij S., Simulation of Wave Scattering at an Orifice by using a Navier-Stokes Solver, AIAA-2007-3402, 13th AIAA/CEAS conference, 21-23 May, 2007.

Kierkegaard A. and Efraimsson G., Generation and Propagation of Sound Waves in Low Mach Number Flows, AIAA- 2007-3485, 13th AIAA/CEAS conference, 21-23 May, 2007.

Efraimsson G., Gong J., Svard M., Nordstrom J., An Investigation of the Performance of a High-Order Accurate Navier-Stokes Code, ECCOMAS CFD 2006, Eggmond aan Zee, Netherlands, September 5-8, 2006.

Kierkegaard A., Efraimsson G., Hoeppfner J., Åkervik E., Henningson D., Åbom M., Identification of Sources of Sound in Low Mach Number Flows by the Use of Flow filed Eigenmodes, 13th International Conference on Sound and Vibration, Wien, Austria, 2006.

Efraimsson G., Biela C., Analysis of Aeroacoustic Wave Propagation Simulations using a Higher- Order Accurate Method, AIAA-2006-2471, AIAA 12th AIAA/CEAS Aeroacoustic conference, Boston, USA, May 8-10, 2006.

Siklosi M., Efraimsson G., Analysis of First Order Errors in Shock Calculations in Two Space Dimensions, SIAM J Numer Anal, , vol 43, No 2, pp 672-685, 2005

Kreiss G., Efraimsson G., Approximate solutions to slightly viscous conservation laws, Quarterly of Applied Mathematics, vol 62, No 1, pp 117-133, 2004

Efraimsson G., Eliasson P., Efficient Interpolation between Rotating and Fixed Grids in Aeroacoustic Calculations, Colloquium EUROMECH 449, Computational Aeroacoustics: From Acoustic Sources Modeling to Far-Field Radiate Noise Prediction, 9-12 December, 2003, Chamonix, Frankrike

Kreiss G., Efraimsson G., Nordström J., Elimination of first order errors in shock calculations, SIAM J Numer Anal, Vol 38, No 6, pp 1986-1998, 2001

Efraimsson G., Nordström J., Kreiss G., Artificial dissipation and accuracy downstream of slightly viscous shocks, AIAA paper 2001-2608, 15th Computational fluid dynamics conference, 11-14 June 2001

Efraimsson G., Kreiss G., A remark on numerical errors downstream of slightly viscous shocks, SIAM J Numer Anal, Vol 36, No 3, pp 853-863, 1999

Efraimsson G., Kreiss G., Numerical errors downstreams of slightly viscous shocks, in Hyperbolic Problems: Theory, Numerics, Applications, Fey M and Jeltsch J (Ed), International series of Numerical Mathematics, Vol 129, 1999

Efraimsson G., A numerical method for the first-order wave equation with discontinuous initial data, numerical methods for partial differential equations, 138(3), pp353-365, 1998

Efraimsson G., A 2D analysis of the influence of artificial viscosity terms on solutions to the Euler equations, Journal of computational physics, 138, pp103-120, 1997

Efraimsson G., Kreiss G., A note on the effect of artificial viscosity on solutions of conservation laws, Applied numerical mathematics, 21, 155-173, 1996

Selected Reports

Efraimsson G., Ingvarsson Á, Nygren M., Reduktion av externt buller från flygande farkoster via strömningsstyrning, Internal report, KTH Aeronautical and Vehicle Engnieeering, KTH, Stockholm, TRITA-AVE-2005:07, 2005

Karasalo I, Efraimsson G, Detektering, klassificering och identifiering från sensor till ledningsnivå, Internal report, KTH Aeronautical and Vehicle Engnieeering, KTH, Stockholm, TRITA-AVE-2005:09, 2005

Efraimsson G., Kreiss G., Approximate solutions to slightly viscous conservation laws, Internal report, NADA, KTH, Stockholm, TRITA-NA 01-40

Jensen K., Efraimsson G., Aero engine fan noise resolution requirement in computational fluid dynamics, Internal report, FOI, Stockholm, FOI-R-0330-SE, 2003

Hetyei Å., Efraimsson G., A numerical study of acoustic waves in a non-homogenous flow, Internal report FOI, Stockholm, FOI-R-0243-SE, 2002

Petrini E., Efraimsson G., Nordström J., A numerical study of the introduction and propagation of a 2D vortex, Internal report, FFA, Bromma, FFA-TN 1998-66

Lindberg N., Efraimsson G., Nordström J., Numerical investigation of extrapolation boundary conditions for the Euler equations, Internal report, FFA, Bromma, FFA-TN 1998-13

Efraimsson G., Kreiss G., Nordström J., Artificial dissipation and accuracy downstream of slightly viscous shocks, Internal report, FFA, Bromma, FFA-TN 1998-70

Efraimsson G., A study of the influence of artificial viscosity terms on solution of conservation laws, PhD thesis, NADA, KTH, Stockholm, 1996