Author: Tim Pertzel

We have just released a new video on our OpenLB YouTube Channel:

Particle Swarm Settling Behavior Spheres and Cubes Using Lattice Boltzmann Methods and OpenLB

This video presents a detailed comparison of the swarm settling (or hindered settling) behavior of volume-equivalent spheres and cubes. The simulation is fully resolved and four-way coupled, showing the dynamic behavior of 1934 particles within a triple periodic domain measuring 15D x 15D x 15D, where D = 3 mm is the diameter of the spheres. The particle volume fraction is approximately 30% and the Archimedes number is set to 2000.

Observations from the video

• Shape matters: Particle shape has a significant effect on the suspension dynamics.
• Average settling velocity: Cubes settle on average approximately 24% slower than the volume-equivalent spheres.
• Clustering: Spheres have a higher tendency to form clusters than cubes.

The simulations were performed with OpenLB using 152 cores (Intel Xeon Platinum 8368 CPU) and both simulations together took less than 13 hours to complete.

Further details and in-depth analysis can be found in the corresponding publications [1, 2].

[1]: J. E. Marquardt, N. Hafen, and M. J. Krause, “A novel model for direct numerical simulation of suspension dynamics with arbitrarily shaped convex particles,” Computer Physics Communications, vol. 304, p. 109321, 2024, doi: 10.1016/j.cpc.2024.109321.

[2]: J. E. Marquardt, N. Hafen, and M. J. Krause, “A novel particle decomposition scheme to improve parallel performance of fully resolved particulate flow simulations,” Journal of Computational Science, vol. 78, p. 102263, 2024, doi: https://doi.org/10.1016/j.jocs.2024.1….

For further information please visit the associated show case: Particle Swarm Sedimentation

The executive committee is happy to announce the closing of the 7^th LBM Spring School with OpenLB Software Lab. We hosted 57 participants from 13 countries this year. Congratulations to Jakob Scheel from the US for winning our poster award. We are already busy with organizing the next spring schools. The 8^th spring school is planned to take place in Marseille, France from May 19-23, 2025. We would like to thank all participants for attending the 7^th spring school in Heidelberg and acknowledge the support from our funders.

On behalf of the spring school executive committee (Kerstin Dick, Shota Ito, Mathias J. Krause and Stephan Simonis)

We have just released a new video on our OpenLB YouTube Channel:

Heterogeneous Load Balancing in OpenLB: Cooperatively Utilizing CPUs and GPUs for a Turbulent Mixing Simulation

Following up on the turbulent micromixer simulation showcased here, the present video illustrates OpenLB’s heterogeneous computation capabilities.

The performance of the simulation case is improved by up to 87% when using heterogeneous CPU-GPU based compared to GPU-only execution. This is achived by distributing the two computationally expensive turbulent inlet regions onto CPUs while the comparatively cheaper bulk regions are processed on GPUs. The underlying inhomogeneous spatial domain decomposition was obtained using a novel genetic algorithm for cost-aware optimization.

A single accelerated CPU-GPU node of the HoreKa supercomputer (2x Intel Xeon Platinum 8368, 4x NVIDIA A100) was used for the showcased simulation consisting of 355 million lattice cells.
OpenLB enabled the cooperative usage of MPI, OpenMP, AVX-512 vectorization and CUDA, reaching a throughput of ~19.25 billion (NSE-only) resp. ~4.79 billion cell updates per second for the fully coupled case.

Simulation setup: Fedor Bukreev
Heterogeneous Load Balancing, Performance engineering, Visualization: Adrian Kummerländer

For further information please visit the associated show case: Heterogeneous Load Balancing

Early bird registration is open until the 4th of February 2024 for the 7th Spring School on Lattice Boltzmann Methods with OpenLB Software Lab. It is held in Heidelberg (Germany), from 4th to 8th of March 2024:

On behalf of the spring school executive committee, Kerstin Dick, Shota Ito, Mathias J. Krause, Stephan Simonis

Registration is now open for the Seventh Spring School on Lattice Boltzmann Methods with OpenLB Software Lab that will be held in Heidelberg/Germany from 4th to 8th of March 2024. The spring school introduces scientists and applicants to the theory of Lattice Boltzmann Methods (LBM) and trains them on practical problems.

Option B: The first half of the week is dedicated to theoretical fundamentals up to ongoing research on selected topics in kinetic theory, scientific computing, LBM, and Partial Differential Equations. Followed by mentored training on case studies using OpenLB in the second half of the week. Emphasis is placed on the modelling and simulation of particulate, multi-component, and turbulent fluid flows.

Option A: Advanced OpenLB users and developers are enabled to solve their own application problems and implement their own solution approaches. All participants benefit from knowledge exchange during the poster session, coffee breaks, and the excursion. We look forward to your participation.

Keep in mind that the number of participants is limited and that the registration follows a first come first serve principle.

• More Information: https://www.openlb.net/spring-school-2024
• Registration: https://www.openlb.net/spring-school-registration

On behalf of the spring school executive committee, Kerstin Dick, Shota Ito, Mathias J. Krause, Stephan Simonis

We are proud to share that our paper “OpenLB—Open source lattice Boltzmann code” (https://doi.org/10.1016/j.camwa.2020.04.033) is ranked 5th on the list of “Top cited articles published in the past 3 years” in the journal Computers & Mathematics with Applications (IF 2.9, SJR Q1 in “Modeling and Simulation” and in “Computational Theory and Mathematics”).

By the way, out of the first five articles in this list, two are on LBM-based software!

In addition, within the list of “The most downloaded articles in the last 90 days” our paper is ranking 6th. Three out of the first six papers in this list use #LBM.

Thank you to the community for citing us, to the team, the co-authors, the co-developers, and especially to Mathias J. Krause for leading the development of #OpenLB in the past years. 

Sources
Scopus: 
https://www.scopus.com/

Elsevier:
https://www.sciencedirect.com/journal/computers-and-mathematics-with-applications

We have just released a new video on our OpenLB YouTube Channel. 

Simulation & Visualization: Jan E. Marquardt, Nicolas Hafen

For further information please view the Show Case dedicated to this topic: Rolling dices under water

The executive committee is happy to announce the closing of the 6th LBM Spring School with OpenLB Software Lab. We hosted 50 participants from 15 countries this year. Congratulations to Martijn Gobes from the Netherlands for winning our poster award.

We are already busy planing next years spring school. The 7th spring school is planned to take place in Heidelberg/Karlsruhe in Germany from March 4th to 8th 2024. 

Thank you all for attending the 6th spring school in Greenwich!

On behalf of the spring school executive committee.

We have just released a new video on our OpenLB YouTube Channel about Multi-GPU Simulation of Turbulent Mixing Using an LES Lattice Boltzmann Model and OpenLB.

Accurate simulations of species transport and mixing with reactions in fluids are a grand challenge in CFD because they require resolving relevant turbulent structure down to the Bachelor scales. We present here our first results for our approach on simulating turbulent confined impinging jets (CIJ) micromixer [Johnson & Prud’homme 2003]. With the help of OpenLB (https://www.openlb.net/) it is now possible to perform an LES-Lattice Boltzmann Method of that case with a newly developed stabilized species transport. The two turbulent inlets are set up with the vortex method and the wall is mapped with a Bouzidi ansatz for a higher precision. The simulation is meshed in parallel in OpenLB with 248 millions cells which are load-balanced and distributed to 24 A100 GPUs of the HoreKA cluster at KIT. The simulation has taken 40 hours to complete 5.4 ms of real time (17.4 residence times). Two species are simulated but only one is visualized.

Simulation & Visualization: Fedor Bukreev, Adrian Kummerländer