PreonLab 5.2 Released

June 09, 2022
We are excited to announce the release of PreonLab 5.2. One reason is that as FIFTY2 we are intrigued by the number 52. But more importantly, PreonLab 5.2 is a huge leap forward for PreonLab and particle-based CFD. It is packed with features that improve reliability, performance and usability across a wide range of applications. Here are some of the highlights:
  • Continuous Particle Size (CPS):  With CPS, each particle stores its own individual size. This new flexibility allows for greater speedups when using refinement and coarsening.
  • Multiphase: Achieve higher accuracy in demanding multiphase simulations without tuning.
  • Thermodynamics: Enhanced sensor capabilities and a new temperature-based density implementation will give you more options for your simulations setups.
  • Car Suspension with AVL VSM: With PreonLab 5.2, a new suspension model is made available in PreonLab as part of the the Vehicle Simulation Model or VSM. This is possible by combining the power of PreonLab with AVL VSM 
  • Usability & Workflow: Import CAD files such as STEP and convert them to the blistering fast and lightweight PRMESH format. Furthermore, enjoy the improved readability of graphs using adjustable axis labels in the Plot Dialog.

This is just a selection of new features and improvements. Check out the changelog to learn about all changes or login with your AVL account to watch the PreonLab 5.2 Release Event on demand.

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Continous Particle Size (CPS)

Two years ago, we introduced local refinement to PreonLab. This is a crucial component of any CFD software because it allows to concentrate computational power on regions where accuracy really matters while saving performance in less prominent regions of the simulation domain.

Previously, PreonLab supported up to 3 resolution levels: The middle level had twice the diameter of the finest level and the coarsest level had four times this diameter. This means that the theoretical limit for particle count reduction (and therefore speedup) was 64, because doubling the particle diameter increases the particle volume by a factor of 8. One of the most frequent feature requests was the addition of a fourth resolution level, which would increase this factor to 512.

PreonLab 5.2 delivers that but it doesn’t stop here. Instead of adding one more level, we abolished the whole concept of levels. In PreonLab 5.2, every particle stores its own size. This does not only allow for unprecedented adaptivity, it also greatly helps with coarsening. Instead of having to find 8 smaller particles which are combined into a bigger particle, the new coarsening can simply combine any amount of suitable neighboring particles into one. This means that fine particles outside refinement zones are coarsened much faster, reducing the overall particle count. We call this new feature Continuous Particle Size (CPS).

A great side effect of CPS is that usability is also improved. Instead of three solver objects (one for each level), all particles are now contained in a single solver. This makes scene setup and post-processing much more intuitive and enjoyable. We hope you will like CPS as much as we do and we cannot wait to see what you will do with it!

Here, CPS is used together with a proximity refinement domain to refine near the boundary. Compared to PreonLab 5.1, the ratio of coarsest to finest particles is increased and particles outside the refinement zone are coarsened immediately.


Single phase simulations are an efficient method to deliver accurate results for many cases involving more than one fluid by modelling the second, less-significant fluid phase as a drag force boundary condition. However, this situation changes when the second fluid phase becomes more influential and introduces additional effects which are not captured in basic single-phase simulations. 
In general, it can be computationally challenging to perform multiphase simulations, especially if the density ratio between the two fluids is high. 
With this in mind, PreonLab 5.1 has made it possible to perform such multiphase simulations in an efficient way. This has proven to be highly advantageous in order to achieve more realistic simulation results for large gearboxes and for cases where high rotational speeds are involved.

PreonLab 5.2 further improves multiphase simulations by introducing a new time-stepping method, which enhances the reliability of simulations even with more challenging setups.

Another new feature in PreonLab 5.2 allows the usage of real bulk modulus values, which enhances the quality and accuracy of the simulation and improves the workflow by eliminating the need to fine-tune setup parameters. 

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The FZG gear has been used to validate the new time-stepping method, obtaining reliable results with identical physical parameters for all operating points of the gear box.


In PreonLab 5.2, a new heat field feature allows the application of a volumetric heat source on individual solvers. The influence of such a heat field can be controlled either by using a solid as a boundary volume or by employing a point cloud resource object with the relevant spatial sampling points.


Furthermore, Sensor plane objects are now compatible with solid volume solvers. Use it to get cross-sectional information about the temperature distribution, e.g., within the windings of an e-motor.


PreonLab 5.2 includes a new temperature-based density implementation that makes use of the new particle size flexibility to adjust the volume of the particles as a response to density changes. It provides a more realistic model for applications relying on this phenomenon.

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Temperature distribution in the windings of an e-motor as a cross-sectional view using the Sensor Plane.

Water Wading simulation with AVL VSM

With PreonLab 5.2, a new suspension model is made available in PreonLab known as the Vehicle Simulation Model or VSM. This is possible by combining the power of PreonLab with AVL VSM

This model uses a quarter car approach dividing the suspension of the car into four regions. You can define the spring and damper settings individually for each section.

The vehicle settings, details of the track and the vehicle kinematics are defined in the user interface of VSM. As before, loading the vehicle and track geometries , defining the transformation groups and interconnecting them and setting up the fluid solver are done in PreonLab. The wheels now have its own masses and sense the depth of the track and PreonLab ensures contact between the tyres and the track without having to use an external script.

With PreonLab and AVL VSM at your hand, you can now perform even more sophisticated water wading simulations, considering uneven tracks and crossflows while having a virtual driver and a powerful car suspension model.

The coupling of PreonLab and AVL VSM is available as an experimental feature and will require a PreonLab and an AVL VSM license. Reach out to your PreonLab contact person at AVL or at FIFTY2 to get the chance for a test drive.

Please agree to the transfer of data to third parties as set out in our privacy policy.

Simulation with PreonLab coupled with an AVL VSM simulation and CPS incorporated.

Usability & Workflow

With PreonLab 5.2, we introduce native support of CAD file formats, in particular the popular STEP file format. The STEP file format benefits from a smaller file size compared to conventional mesh-based file formats such as STL due to its representation of the raw geometry data, but suffers from a longer loading time due to the necessary tessellation of the geometry data. Therefore, we have combined different concepts in order to give you the option to convert the imported CAD file into our very own PRMESH file format, which consumes even less hard drive space while loading blazing fast.  

Having a material library offering presets has been a frequent request. With PreonLab 5.2 you now have the option to easily define and save your material settings for any object. Make sure you also share those valuable settings with you colleagues – sharing is caring.

Getting the right data from PreonLab is now even more convenient. The readability of the graphs in the Plot Dialog has been improved by adding adjustable axis labels which of course will be part of exported graphs.

Other Changes

Check out the changelog for a full list of changes. To learn more about the new features, have a look at the updated manual. We hope you will enjoy working with PreonLab 5.2 and as always, we would appreciate your feedback.



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