Category: News

Registration is now open for the Fifth Spring School on Lattice Boltzmann Methods with OpenLB Software Lab that will be held in Kraków, Poland from 21^st to 25^th of March 2022. The spring school introduces scientists and applicants from industry to the theory of LBM and trains them on practical problems. The first half of the week is dedicated to the theoretical fundamentals of LBM up to ongoing research on selected topics. Followed by mentored training on case studies using OpenLB in the second half, where the participants gain deep insights into LBM and its applications. This educational concept offers a comprehensive and personal guided approach to LBM. Participants also benefit from the 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.

On behalf of the spring school executive committee, Nicolas Hafen, Mathias J. Krause, Jan E. Marquardt, Paweł Madejski, Tomasz Kuś, Navaneethan Subramanian, Maciej Bujalski and Karolina Chmiel

(Covid) Virus Risk Simulation of a Person Breathing Using an Air Ventilation Systems with LBM – Simulations in Process Engineering

Are ventilation systems effective against aerosol emission from breathing?

A typical way of transmitting viruses like SARS-CoV-2 is through saliva aerosol particles which are sprayed in the air by coughing or sneezing but also through breathing. If these droplets are inhaled by another person there is a high infection risk. To minimize the potential risk of transmitting the virus through the air ventilation systems should keep aerosol particles concentrations low.

The simulation is able to show the turbulent flight path of the aerosol stream transmitted by a sitting person. This demonstrates the importance and difficulties of a ventilation systems in order to decrease infection risk by reducing aerosol particle concentrations. 

These videos present the aerosol distributions generated by a breathing human. In every breath, 10,000 particles with diameter of 1 μm are omitted through the mouth. The mesh contains 65.5 millions cells (δx=4.8mm). 10 seconds were simulated using a cluster with 400 cores (20 nodes). The source code is available for download on the OpenLB website. 

The fluid flow in the artificial set-up was validated by means of experments and other simulations. These benchmark was published in “Numerical evaluation of thermal comfort using a large eddy lattice Boltzmann method”, M Siodlaczek, M Gaedtke, S Simonis, M Schweiker, N Homma, MJ Krause, Building and Environment, 107618 .

For further information please view our dedicated page about this topic: (Covid) Virus Risk Simulation

Data and Simulation: Simon Berg, Fedor Bukreev, Mathias J. Krause

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

The OpenLBee showcase illustrates a bee at a realistic Reynolds number in its landing approach. The bee was placed in a rectangular flow domain. The flow is driven by a velocity inlet and a pressure outlet boundary condition, while for the other plane of the box a symmetry conditions is set. An LES-LBM turbulence scheme is used and a wall model is applied to deal with the boundary layer separation of the thin wings in an efficient way. For the visualization Blender was used.

For further information please view the dedicated Show Case: OpenLBee

Data and Simulation: Jonathan Jeppener-Haltenhoff

Visualization: Daniel Krug

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

These videos present the aerosol distributions generated by a breathing human. In every breath, 10,000 particles with diameter of 1 μm are omitted through the mouth. The mesh contains 65.5 million cells (δx=4.8mm). 10 seconds were simulated using a cluster with 400 cores (20 nodes). The results show the very different aerosol distributions (yellow) and the deposit particles (blue) in two different scenarios: without background air flow (left) and with an air flow of 10 m/s by a filter vent (right).

For further information please view the Show Case dedicated to this topic: Indoor Aerosol Distribution Patterns

Contributed by Mathias J. Krause, Fedor Bukreev, Simon Berg

We are very happy to announce that we have just published our new OpenLB Overview Paper. You can find it on pages 258-288 in volume 81 of Computers & Mathematics with Applications. This paper summarizes the findings of the research that was conducted with OpenLB and gives a brief introduction to the underlying concepts as well as the design of the parallel data structure. It is a great read for newcomers as well as seasoned OpenLB users.

The paper can be viewed and downloaded here: http://www.sciencedirect.com/science/article/pii/S0898122120301875 

The developer team is very happy to announce the release of the next version of OpenLB. The updated open-source Lattice Boltzmann (LB) code is now available for download. 

The changes and new features are:

• Enhanced user experience for interfaces: 
  • Complete overhaul of the core data structure (population and field data) 
  • Improved boundary handling (better interface and easier extension possibilities)  
  • Overhaul of HLBM, now with updated momentum exchange algorithm and Kupershtokh forcing 
• Additional multiphysics models: 
  • New mixed scale diffusivity turbulence model in 2D and 3D 
  • New phase field-based multi component model in 2D and 3D 
  • New total enthalpy-based melting and solification model in 2D and 3D 
• Performance improvements in some workloads: 
  • New propagation pattern
  • Communication improvements via reworked coupling routines using dynamic fields 
  • Average speed up of about 28% for the example cases 
• New examples: 
  • turbulence/channel3d
  • thermal/stefanMelting2d
  • thermal/galliumMelting2d
  • thermal/advectionDiffusion1d
  • thermal/advectionDiffusion2d 
• Minor improvements and developer notes:
  • revision of example laminar/bstep2d
  • all fields declared in the descriptor are now included in simulation snapshots
  • fields may now use types different than the lattice’s floating point type
  • new _dynamic fields_ allow using the field interface also for fields that are declared at runtime
  • Knudsen number and refinement quality functors are now available in both 2D and 3D
• Compatibility tested on:
  • OSX: 
    • macOS 10.13.6: Clang 10 (1000.10.44.4)
  • Linux: 
    • Intel 18, 19, 19.1
    • GCC 7.5, 8.2.1, 9.3, 10.2
    • Clang 7
  • Windows 10: 
    • Debian WSL: GCC 7.5, 8.2.1, 9.3

Intel MPI 2019 Update 5, OpenMPI 2.1.1 and higher

PS: Please consider joining the developer team by contributing your code. Together we can strengthen the LB community by sharing our research in an open and reproducible way! Feel free to contact us here.

We have released two new Videos on our OpenLB YouTube Channel. The first Video is about a 3D simulation of blood flowing through the human aorta. The second one visualizes phase separation in 3D.

For further information please visit the corresponding show case:

• Blood Flow Simulation
• Phase Separation

Data and Simulation: Mathias J. Krause 

Visualisation: Max Mutter, Jan Marquardt, Mathilde Wu

Data and Simulation: Peter Weisbrod, Mathias J. Krause 

Visualisation: Fabian Kösegi, Jan Marquardt, Mathilde Wu

In a collaboration of the Lattice Boltzmann Research Group (LBRG) at the Karlsruhe Institute of Technology (KIT) and the Institute of Reactive Flows and Diagnostics of the department of Mechanical Engineering at the Technical University of Darmstadt, the capabilities of two open source near-wall-modeled large eddy simulation (NWM-LES) approaches were investigated to predict complex turbulent flows relevant to internal combustion (IC) engines.

Therefore, OpenLB was compared to the commonly applied open source tool OpenFOAM, using a highly precise particle image velocimetry measurement as reference. The comparison covers prediction accuracy, computational costs and ease of use.

The performance results show that the OpenLB approach is on average 32 times faster than the OpenFOAM implementation for the tested configurations. The faster calculation speed for NWM-LES using the lattice Boltzmann method implementation in OpenLB is advantageous to address industrial applications and to enable “overnight” calculations that previously took weeks.

Checkout our recent publication for more details: https://www.mdpi.com/2079-3197/8/2/43

2020/03/13 | LBM Spring School with OpenLB Software Lab successfully finished. The executive committee announces the closing of the third LBM Spring School with OpenLB Software Lab. We were happy to host 60 participants from nine countries, including five invited speakers in Berlin, Germany. This year’s poster award goes to Dominik Wilde et al. from the University of Siegen, Germany.

Next year, the 5^th spring school (https://www.openlb.net/spring-school-2021/) in planned to take place at the University of Greenwich in England/UK form 2021 May 31^st to June 4^th.  

On behalf of the spring school executive committee, Nicolas Hafen, Mathias J. Krause, Harald Kruggel-Emden, Christopher McHardy, Cornelia Rauh, Holger Stark, Robin Trunk

Early bird registration is open until the 10th of February 2020 for the Fourth Spring School on Lattice Boltzmann Methods with OpenLB Software Lab. It is held in Berlin, Germany, from 9th to 13th of March 2020. 

On behalf of the spring school executive committee, Nicolas Hafen, Mathias J. Krause, Harald Kruggel-Emden, Christopher McHardy, Cornelia Rauh, Holger Stark, Robin Trunk