PreonLab 3.2 is here! Besides numerous smaller improvements, this release also includes major innovations that open up new applications and new workflows:

• Implicit viscosity solver: The new (optional) solver is capable of simulating highly viscous fluids at large timesteps and superior performance.
• Optimized post-processing: PreonLab 3.2 greatly reduces the system requirements for post-processing and improves overall responsiveness of the user interface for large scenes.
• Keyframe spline interpolation: The new interpolation method significantly reduces the effort to generate smooth interpolation between keyframes and makes defining kinematics even easier than before.
• Unified Area source with cone support: All two-dimensional fluid sources are now unified into one. The new versatile Area source also introduces a conical emission shape.

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New implicit viscosity solver

In previous PreonLab versions, simulations with highly viscous fluids were only possible with a very small timestep. This resulted in poor performance and effectively prevented the usage of PreonLab for these scenarios. PreonLab 3.2 introduces an implicit viscosity solver that imposes no restrictions on the timestep and therefore greatly improves the performance in these cases. The image below shows an example: Without the new viscosity solver, even this simple scenario would require more than a full day to simulate because of the low timestep required for the high viscosity. With PreonLab 3.2, this case can be simulated in less than an hour.

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Optimized post-processing

PreonLab 3.0 added support for distributed simulations using MPI, which allowed for previously impractical simulations with hundreds of millions of particles. However, we received feedback (and experienced ourselves) that post-processing these simulations using PreonLab on a typical workstation was highly problematic or even impossible. PreonLab simply could not deal with the massive amount of data that the distributed simulation generated. For PreonLab 3.2, we analyzed typical bottlenecks during post-processing and introduced measures to combat them:

• Firstly, we left no bit unturned to reduce memory consumption during post-processing. The savings vary from scene to scene and can range from anywhere between a factor of 1.5 and 10. In many cases, this makes all the difference between being able to open a scene on a common workstation or experiencing a crash or even system freeze. The saved resources also often result in significantly faster scene loading.
• Secondly, we added the possibility to specify a target number for rendered particles. If this limit is exceeded, PreonLab will downsample the fluid particles adaptively for rendering, ensuring interactive framerates.
• Thirdly, we optimized the loading and decoding of particle data from disk. This can speed up playback / post-processing performance by up to 30%.

These optimizations represent a benefit for all users, even if MPI is not used.

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Keyframe spline interpolation

Keyframing is a powerful tool in PreonLab that enables the engineer to define complex kinematics and helps to generate meaningful animations. With PreonLab 3.2 we introduce spline interpolation as an additional option for defining the interpolation curve. Spline interpolation allows to model smooth functions with just a few keyframes and eliminates the need to fine-tune the interpolants between keyframes manually. This significantly reduces the effort, especially when modelling oscillating values.

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Unified area source with cone support

The old Area, Circle, Flat Jet, Rain and Square sources are now combined into one new source called Area source. The new source supports all features that the old sources offered, but also introduces new capabilities. For instance, it is now possible to use rain emission for a flat jet or seedpoint-defined source area. The new source also adds a new conical emission area type. The image below shows pathlines for conical and flat jet rain emission with different opening angles.