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May 2021 - Aeroacoustic Simulations of Low-pressure Axial Fan for Battery Cooling Units

New Release

The new release of openCFS-2021S is available online under the MIT license.


This autumn, the annual users meeting will be in Vienna from Thursday, September 23 until Friday, September 24. Presentation request should be sent to florian.toth@tuwien.ac.at.

Recent contributions to openCFS

Recently, we have provided support for intel compilers and optimized the openCFS builds for native architectures.

  • Support for intel compilers (c++ and Fortran)
  • Optimized builds for native architecture
  • Bugfixes
Latest Publications
  • Freidhager, C., et al. Simulationen von Strömungsakustik in rotierenden Bauteilen zur Entwicklung von Antriebskonzepten der Autos der Zukunft. Elektrotech. Inftech. (2021). 10.1007/s00502-021-00887-0
  • Maurerlehner, P., et al. Efficient numerical simulation of the human voice. Elektrotech. Inftech. (2021). 10.1007/s00502-021-00886-1
  • K. Roppert, et al.  Sliding Non-Conforming Interfaces for Edge Elements in Eddy Current Problems, in IEEE Transactions on Magnetics, 57, 3, 1-6, (2021) 10.1109/TMAG.2020.3049059.
  • Floss, S., et al. Micro-perforated panels for noise reduction. Elektrotech. Inftech. (2021). 10.1007/s00502-021-00889-y
  • Toth, F., et al. Acoustics on small scales. Elektrotech. Inftech. (2021). 10.1007/s00502-021-00875-4

Application - Aeroacoustic Simulations of Low-pressure Axial Fan for Battery Cooling Units

by S. Schoder: stefan.schoder@tugraz.at , A. Wurzinger, C. Freidhager, M. Kaltenbacher, IGTE, TU Graz

HVAC System Simulation

Future power units of cars (the electric motor, battery, fuel cell) generate little noise during operation. Consequently, the noise of auxiliary units (cooling fan of a battery unit, the turbocharger of fuel cells [1] becomes an essential task of the developing process. Since performing robust measurements are costly and time-consuming, the presented validated simulation workflow enhances development and research [2].

Details on the Study

Within this finished research project, we investigated the individual steps of the hybrid aeroacoustic workflow in detail. Based on existing benchmark data for low-pressure axial fans [3], the perturbed convective wave equation (PCWE) and the Ffowcs Williams and Hawkings analogy Farassat’s 1A (FWH) are analyzed. We performed a mesh convergence study and altered the turbulence modeling approach (visualization see Fig. 1).

Fig. 1: Q-criterion at instantaneous time, which is showing the turbulent structures of the tip flow.

The detached eddy simulation model and a grid of 23.4million cells delivered the most accurate sound radiation (see Fig. 2). The validation of the results allows us to conclude that the fluctuating flow pressure is the relevant flow-convergence criteria, motivated by the fact that it is the dominant source term both for PCWE and FWH.

Fig. 2: Sound propagation visualization.

Key Results

Furthermore, we showed the robustness of the developed grid interpolation techniques [4] using the Richardson extrapolation. Considering the short duct, we found that for frequencies below 700Hz, FWH and PCWE deliver a comparable accuracy of sound prediction [2]. However, for sources at a higher frequency, the directivity of the propagation matters (which the PCWE accounts for). Since most industrial applications have complicated geometries, including in-duct systems, the PCWE (discretized by the finite element method) is preferable.

[1] Freidhager, C. et al. "Simulationen von Strömungsakustik in rotierenden Bauteilen zur Entwicklung von Antriebskonzepten der Autos der Zukunft". Elektrotech. Inftech. (2021) 10.1007/s00502-021-00887-0
[2] Schoder, S. et al. "Computational aeroacoustics of the EAA benchmark case of an axial fan." Acta Acustica 4.5 (2020): 22.10.1051/aacus/2020021
[3] European Acoustics Association: Benchmark Cases for Computational Acoustics. 2017.
[4] Schoder, S. et al. "Application limits of conservative source interpolation methods using a low Mach number hybrid aeroacoustic workflow." JTCA 29.1 (2021). 10.1142/S2591728520500322













Static Analysis

Transient Analysis

Harmonic Analysis

Multi-Harmonic Analysis

Eigenfrequency Analysis

Nonconforming Grid

Model Order Reduction

Structural Optimization


Association for the promotion of the software

Verein zur Förderung der Software openCFS

The association "Verein zur Förderung der Software openCFS" has been founded in 2020 and its main goal is the promotion of the open source software openCFS. The main objectives of the association are

  • Comprehensive maintenance and further development of the open source software openCFS
  • Promotion of the use of openCFS for scientific problems which are solved with the help of numerical simulation, thus leading to new, innovative products for the benefit of mankind (Technology for People)
  • Promotion of the scientific documentation of openCFS and the use of openCFS in higher education
  • Promotion of young scientists, especially students at universities in Austria and Germany and worldwide, in the field of numerical simulation of complex technical systems

User prize presentation

Once a year a user prize is awarded within the framework of a user meeting.

Developer prize presentation

Once a year a developer prize is awarded within the framework of a user meeting.


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