See the flow.
Shape the design.

GPU-native CFD for early-stage design.

Load geometry from your CAD tools, run complex free-surface cases, compare design variants and operating conditions before the design is fixed.

Define a tank, its fill level, and the motion.01 / Set up

Side view of a rectangular tank with a shallow layer of water at rest.

Prelimina simulation of the tank shaken side to side: a wave travels back and forth and runs up each end wall.

The same tank and motion with a floor baffle at mid-length.

Some Applications.

Validation cases and demonstrations, from tank sloshing to wetting in microgravity.

Side view of the tank as the water sloshes and slams into the end wall, coloured by speed. Below it, the simulated pressure at the wall probe P1 draws in step with the motion over the measured trace; each impact spike lines up with a measured one.

Check sloshing wall pressure against experiment.

Shake a shallow tank side to side and compare the wall-pressure history with published measurements.

Perspective view of a long tank. A column of water at the far end collapses, runs along the floor, slams into a small box and sprays over it, then sloshes back. Below it, the simulated pressure on the front of the box draws in step over the measured trace.

Check a dam-break impact on a box against experiment.

Release a column of water onto a box in a long tank and compare the impact pressure and water levels with measurements.

Side cutaway of a tank draining through two horizontal pipes. Both jets run at first; the upper jet thins and stops once the level falls below its pipe, while the lower jet keeps flowing.

Follow water through two outlets.

Watch a tank drain through two pipes at different heights as the water level falls.

The labyrinth spillway set up in the Prelimina interface, followed by an orbit around the exported flow: water released through two gates runs down the chute, coloured by speed.

Watch a gated spillway release.

Lift the gates on a labyrinth spillway and follow the released water over the crest and down the chute.

Two identical tanks shaken side to side. At 1 g a single wave travels the tank; at 0.01 g the liquid is thrown up the walls in thin sheets that arc slowly back down.

Compare sloshing at reduced gravity.

Shake the same tank the same way at 1 g and at 0.01 g and compare how the liquid moves.

Two half-filled spherical tanks side by side. After gravity drops, the wetting liquid on the left climbs the wall and leaves a curved hollow; the non-wetting liquid on the right pulls away from the wall and rises into a dome.

Wetting takes over in microgravity.

Drop a half-filled spherical tank from 0.1 g to 0.001 g and watch surface tension and the wall contact angle reshape the liquid.

Side view of a long, closed tank rolling a few degrees each way. The shallow water runs to one end and slams into the left wall, sending a sheet up the wall to the lid, then runs back; four times in all. Below it, the simulated pressure at the wall sensor S1 draws in step over the measured trace, each impact lining up with a measured one.

Check pressure in a sloshing tank.

Roll a shallow water tank with the measured motion of SPHERIC benchmark Test 10 and compare the wall pressure through four lateral impacts.

A cube seen from one corner, with the nearest eighth cut away to show the inside. It starts dark red and cools from its edges and corners inwards, turning green and then blue while the centre stays warm longest. Below it, the simulated temperatures at the centre, a face centre and a corner draw in step over the exact curves and stay on them.

Check heat conduction in a cooling block against the exact solution.

Cool a hot steel cube through all six faces and compare the temperature at its centre, a face and a corner with the exact solution.

A square box of air, hot on the left wall and cold on the right. Arrows show the air rising along the hot wall, crossing the top, sinking along the cold wall and returning along the floor, while the box fills with warm air above and cool air below. Below it, the hot-wall heat flow draws in step: it jumps at the start, dips, and then settles on the dashed benchmark line.

Check buoyant air flow in a heated box against a benchmark.

Heat one wall of a closed box of air and cool the opposite one, and compare the heat flow and the air speeds with the standard natural-convection benchmark.

A section through the centre plane of a horizontal cylindrical tank with rounded ends, a quarter full of water, pitching three degrees each way. A wave runs back and forth along the tank and climbs the end walls; each time it passes under the sensor on the roof near the left end, the water there rises and falls. Below it, the simulated elevation at the sensor draws in step over the measured trace.

Check sloshing in a pitching fuel tank against experiment.

Pitch a cylindrical LNG fuel tank near its first sloshing mode and compare the free-surface elevation at a roof sensor with measurements and a published 3D RANS simulation.

Section through the middle of the closed tank, seen in the tank frame, over two forcing periods. The water, coloured by speed, runs along the floor, climbs the right-hand end wall and falls back, then runs to the left wall and back again; the air above it is light grey. Below it, the simulated pressure at the wall probe P1 draws in step over the measured trace, rising with each measured impact.

Check sloshing wall pressure with the air resolved.

The same tank as application 01, now with the air resolved: shake the closed tank side to side with both water and air simulated, and compare the wall-pressure impulse with published measurements.

All 11 applications

Any platform. Full power.

Run it in your browser or on the desktop, with the same GPU solver behind both. Set up the case and watch the flow and the probe readings update together.

The Prelimina window in the Simulate tab: the Kishev sloshing tank seen from the side with a wave coloured by speed running up the right wall, display settings on the left, and below it the pressure at probe P1 over the run with the measured pressure from the experiment drawn over it as a grey reference curve. — Live probe pressure (blue) against the measured pressure of Hu, Kashiwagi & Kishev (2004), grey.

Use it in the browser Download for desktop

What the solver does.

No meshing

Bring triangulated surfaces straight from your CAD tools. Complex vessels, baffles, and internal parts work as they are, with no volume mesh to build.

Moving geometry

Rotate, oscillate, shake, or accelerate the geometry. The liquid splashes, breaks up, and reconnects, keeping a sharp surface through impacts, with surface tension and wetting acting at the interface.

Runs on your GPU

Every simulation step runs on the graphics card in your workstation, and memory follows the liquid rather than the empty space around it. Watch the result take shape while it runs.

Coupled physics

Simulate multiple phases. Couple the liquid to free-moving bodies and structural solvers. Choose non-Newtonian fluids. Transfer heat through the liquid. Viscoelasticity is on the roadmap.

Batch runs and optimisation

Dimensions, fill levels, motion, and fluid properties are all plain setup inputs. Run batches of variants from the command line, compare the results automatically, or drive the solver from your own optimisation loop.

Controllable by AI

Plain, schema-validated setup files and packaged CLI/MCP tools let AI agents check setups and run CFD tasks. A local setup assistant is experimental.

Explore all capabilities

Full feature list, with the status of each one.

Built by people who write and use solvers.

Prelimina is developed by PLASMICA Ltd., a spin-out from the University of Split, Croatia. Most of the team hold PhDs in fluid dynamics, numerical methods, engineering, and have spent their careers between university research and industrial applications, from deep sea to deep space.

About the company

PhDResearch-trained core team: Fluid dynamics, numerical analysis, HPC, and machine learning are the fields the team publishes and teaches in.
100+Years of combined experience: Across academic research and engineering work for industrial clients in aerospace, marine, and manufacturing.
In-houseMethods written by the team: Every solver in Prelimina is designed, implemented, and used by the people who answer your questions about it.

Download desktop app.

Free for noncommercial use. Windows and Linux now, macOS and a browser version later.

Current version: v0.3.0
Release date: 27 October 2026
Changes: Changelog

Windows

System: Windows 10 22H2 (64-bit) or newer.
GPU: GPUs from 2015 onward that support Vulkan 1.3, with recent drivers.
RAM: 8 GB minimum.
VRAM: 4 GB estimated small-scene floor; 6–8 GB preferred. Larger workloads: 8–12 GB or more.

Download for Windows

Linux

System: 64-bit Linux (x86-64), glibc 2.28 (2018) or newer.
GPU: GPUs from 2015 onward that support Vulkan 1.3, with recent drivers.
RAM: 8 GB minimum.
VRAM: 4 GB estimated small-scene floor; 6–8 GB preferred. Larger workloads: 8–12 GB or more.
Runtime: FUSE 2 for AppImage mounting.

Download for Linux

macOS

System: Supported macOS versions to be announced.
GPU: Graphics support to be confirmed.
Memory: RAM minimum to be confirmed.

Full features and commercial licence

Development versions (<1.0) offer all implemented features, free for noncommercial use.
Commercial use always needs a licence, including business evaluation.

Price: €700 per seat per year, plus VAT where applicable
50% discount: Freelancers, startups, and university research funded by a company.
Includes: Every release during the subscription. Support is not included. 14-day refund.

Ask about licensing Terms Refund policy

FAQ

Licensing, supported hardware, and what Prelimina is for.

Read the full agreement Ask about licensing

Is Prelimina free?

Yes, during the development phase; for lawful noncommercial use: personal projects, learning, teaching, and research without a commercial purpose. No purchase, subscription, academic affiliation, or separate permission is required. Development versions (before 1.0) include all features, and keep them. From version 1.0, the free version may be limited, for example to the FLIP solver without CUDA acceleration and with a limited cell count; full features will need a licence. Commercial use is never free.

Can I use it for commercial work?

Yes, with a paid commercial licence or subscription before the work begins. This includes business evaluation, internal design work, and consulting. Eligibility depends on the purpose of the work, not your organisation’s status.

Are there limits on noncommercial use?

The licence places no limits on users, installations, computing capacity, simulation size, or duration of noncommercial use. Your hardware still determines which simulations you can run.

Do I keep my data and results?

Yes. You retain your rights in your data, designs, and results. The agreement gives PLASMICA no permission to publish them or use them to train AI models. Commercial use of results requires the appropriate entitlement.

What is Prelimina for?

Practical early-stage fluid-design work, initially focused on sloshing, baffle arrangements, and free-surface motion. It is being developed for engineering teams, equipment designers, consultants, laboratories, and educators who want to understand a response before the next design iteration.

Can I download Prelimina today?

Yes, you can download the desktop application. But note that Prelimina is in development, and the application is not yet ready for production use.

Which GPUs and operating systems are supported?

The Download section lists Windows and Linux requirements. We have tested the application on Windows 10 22H2 and 11, Linuxes since 2020, and various GPUs from 2015 onwards.

Does it run in my browser?

The browser version of Prelimina is currently in development and coming soon. It will run natively in your browser. The interactive workflow illustration on this website explains an engineering task; it does not run a fluid simulation.

See the flow.Shape the design.