LBRG

Over the past six months, the LBRG at KIT has had the absolute pleasure of hosting and working alongside Flavia Zinani (Professor at the Federal University of Rio Grande do Sul - UFRGS) and Leonardo da Luz Dorneles (Doctoral Researcher from the Laboratory of Structural Bioinformatics and Computational Biology - SBCB).

During their time with us, they made fantastic contributions to our research:

🌊 Flavia focused on simulating wave-energy converters using OpenLB.

💻 Leonardo developed and evaluated optimization methods for massively parallel architectures and helped improve the CSE of collision kernels in OpenLB.

Both contributed extensively not just to our projects, but to the spirit of our group. We had a wonderful time together and already look forward to crossing paths again soon. Until then, we wish you all the best! Flavia and Leonardo’s visits are supported by the collaborative project between UFRGS and KIT: 'MCTI/CNPq 16/24 - Computational Fluid Dynamics and Machine Learning for Sustainable Engineering.'

LBRG

The Lattice Boltzmann Research Group at KIT is very excited to share our latest paper: “Geometry reconstruction from magnetic resonance velocimetry measurements via solving an inverse fluid flow problem”, as a result of the collaboration between Shota Ito, Alexander Zimmermann, Julius Jeßberger, Stephan Simonis, Adrian Kummerlander, Fedor Bukreev, Jorg Thoming, Georg Pesch und Mathias J. Krause.

The paper provides an alternative to computationally expensive imaging techniques like Computed Tomography (CT) for obtaining the geometry of flow domains. This is achieved by solving an inverse Navier-Stokes problem, where the geometry (specifically the permeability distribution) is iteratively adjusted until the simulated velocity distribution matches the measured experimental data.

Key highlights of the paper:

Innovative geometry reconstruction: it is demonstrated that complex geometries like OCFs can be reconstructed from velocity data with high fidelity (achieving a Jaccard index of 0.91 in simulations)

Performance on real data: when tested with experimental Magnetic Resonance Velocimetry (MRV) data, the method achieved a 12% improvement in the recovered geometry compared to traditional segmentation methods based on MRI signal amplitude images

Noise Reduction: the inverse optimization process acts as a filter, reducing non-physical noise signals inherent in experimental MRV data by restricting the optimized flow field through the underlying conservation equations

The proposed method in the paper offers several advantages for numerical studies, including:

- reducing the reliance on expensive, invasive and time-consuming CT-Scans
- eliminating the tedious manual labor often required for aligning and positioning CFD and experimental data
- providing an automated approach for validating simulated flow fields against measurements

The paper is published open access and may be found here. 
 

LBRG

Our team members Shota Ito, Johannes Grafen, and Stephan Simonis from the Lattice Boltzmann Research Group (LBRG) Boltzmann Research Group (Karlsruher Institut für Technologie (KIT)) attended the 13th ICCFD: International Conference on Computational Fluid Dynamics (ICCFD13) in Milan, together with our research partner Arsh Kumbhat from the CAMLab at ETH Zurich!
In addition to attending inspiring talks and dynamic group sessions across a huge variety of CFD research fields, we had the great opportunity to connect with fellow researchers from around the world.

Overall, we contributed three talks:

- Generation of efficient adjoint lattice Boltzmann collision kernels with reverse mode algorithmic differentiation by Shota Ito
- Turbulent Fluid Flow Sampling with OpenLB-UQ by Johannes Grafen
- Probabilistic Lattice Boltzmann Methods for Statistical Solutions of Turbulent Flows by Stephan Simonis

A huge thank you to the local organizing committee, Alberto Guardone and Barbara Re, for hosting such a fantastic event at Politecnico di Milano!
We also want to express our gratitude to the DAAD Deutscher Akademischer Austauschdienst (German Academic Exchange Service) for the Conference Travel Program scholarship, funded by the Auswärtiges Amt (Federal Foreign Office) Germany. Thanks to the Conference Travel Program,
Shota, Johannes and Stephan were able to attend this international event and share their research.