FluidX3D

The fastest and most memory efficient lattice Boltzmann CFD software, running on all GPUs and CPUs via OpenCL. Free for non-commercial use.

<a href="https://youtu.be/-MkRBeQkLk8"><img src="https://img.youtube.com/vi/o3TPN142HxM/maxresdefault.jpg" width="50%"></img></a><a href="https://youtu.be/1z5-ddsmAag"><img src="https://img.youtube.com/vi/1z5-ddsmAag/maxresdefault.jpg" width="50%"></img></a><br> <a href="https://youtu.be/2BPP1oWzvi0"><img src="https://img.youtube.com/vi/2BPP1oWzvi0/maxresdefault.jpg" width="50%"></img></a><a href="https://youtu.be/K5eKxzklXDA"><img src="https://img.youtube.com/vi/K5eKxzklXDA/maxresdefault.jpg" width="50%"></img></a> (click on images to show videos on YouTube)

<details><summary>Update History</summary>

• v1.0 (04.08.2022) changes (public release)
  • public release
• v1.1 (29.09.2022) changes (GPU voxelization)
  • added solid voxelization on GPU (slow algorithm)
  • added tool to print current camera position (key <kbd>G</kbd>)
  • minor bug fix (workaround for Intel iGPU driver bug with triangle rendering)
• v1.2 (24.10.2022) changes (force/torque computation)
  • added functions to compute force/torque on objects
  • added function to translate Mesh
  • added Stokes drag validation setup
• v1.3 (10.11.2022) changes (minor bug fixes)
  • added unit conversion functions for torque
  • FORCE_FIELD and VOLUME_FORCE can now be used independently
  • minor bug fix (workaround for AMD legacy driver bug with binary number literals)
• v1.4 (14.12.2022) changes (Linux graphics)
  • complete rewrite of C++ graphics library to minimize API dependencies
  • added interactive graphics mode on Linux with X11
  • fixed streamline visualization bug in 2D
• v2.0 (09.01.2023) changes (multi-GPU upgrade)
  • added (cross-vendor) multi-GPU support on a single node (PC/laptop/server)
• v2.1 (15.01.2023) changes (fast voxelization)
  • made solid voxelization on GPU lightning fast (new algorithm, from minutes to milliseconds)
• v2.2 (20.01.2023) changes (velocity voxelization)
  • added option to voxelize moving/rotating geometry on GPU, with automatic velocity initialization for each grid point based on center of rotation, linear velocity and rotational velocity
  • cells that are converted from solid->fluid during re-voxelization now have their DDFs properly initialized
  • added option to not auto-scale mesh during read_stl(...), with negative size parameter
  • added kernel for solid boundary rendering with marching-cubes
• v2.3 (30.01.2023) changes (particles)
  • added particles with immersed-boundary method (either passive or 2-way-coupled, only supported with single-GPU)
  • minor optimization to GPU voxelization algorithm (workgroup threads outside mesh bounding-box return after ray-mesh intersections have been found)
  • displayed GPU memory allocation size is now fully accurate
  • fixed bug in write_line() function in src/utilities.hpp
  • removed .exe file extension for Linux/macOS
• v2.4 (11.03.2023) changes (UI improvements)
  • added a help menu with key <kbd>H</kbd> that shows keyboard/mouse controls, visualization settings and simulation stats
  • improvements to keyboard/mouse control (<kbd>+</kbd>/<kbd>-</kbd> for zoom, <kbd>mouseclick</kbd> frees/locks cursor)
  • added suggestion of largest possible grid resolution if resolution is set larger than memory allows
  • minor optimizations in multi-GPU communication (insignificant performance difference)
  • fixed bug in temperature equilibrium function for temperature extension
  • fixed erroneous double literal for Intel iGPUs in skybox color functions
  • fixed bug in make.sh where multi-GPU device IDs would not get forwarded to the executable
  • minor bug fixes in graphics engine (free cursor not centered during rotation, labels in VR mode)
  • fixed bug in LBM::voxelize_stl() size parameter standard initialization
• v2.5 (11.04.2023) changes (raytracing overhaul)
  • implemented light absorption in fluid for raytracing graphics (no performance impact)
  • improved raytracing framerate when camera is inside fluid
  • fixed skybox pole flickering artifacts
  • fixed bug where moving objects during re-voxelization would leave an erroneous trail of solid grid cells behind
• v2.6 (16.04.2023) changes (Intel Arc patch)
  • patched OpenCL issues of Intel Arc GPUs: now VRAM allocations >4GB are possible and correct VRAM capacity is reported
• v2.7 (29.05.2023) changes (visualization upgrade)
  • added slice visualization (key <kbd>2</kbd> / key <kbd>3</kbd> modes, then switch through slice modes with key <kbd>T</kbd>, move slice with keys <kbd>Q</kbd>/<kbd>E</kbd>)
  • made flag wireframe / solid surface visualization kernels toggleable with key <kbd>1</kbd>
  • added surface pressure visualization (key <kbd>1</kbd> when FORCE_FIELD is enabled and lbm.calculate_force_on_boundaries(); is called)
  • added binary .vtk export function for meshes with lbm.write_mesh_to_vtk(Mesh* mesh);
  • added time_step_multiplicator for integrate_particles() function in PARTICLES extension
  • made correction of wrong memory reporting on Intel Arc more robust
  • fixed bug in write_file() template functions
  • reverted back to separate cl::Context for each OpenCL device, as the shared Context otherwise would allocate extra VRAM on all other unused Nvidia GPUs
  • removed Debug and x86 configurations from Visual Studio solution file (one less complication for compiling)
  • fixed bug that particles could get too close to walls and get stuck, or leave the fluid phase (added boundary force)
• v2.8 (24.06.2023) changes (documentation + polish)
  • finally added more documentation
  • cleaned up all sample setups in setup.cpp for more beginner-friendliness, and added required extensions in defines.hpp as comments to all setups
  • improved loading of composite .stl geometries, by adding an option to omit automatic mesh repositioning, added more functionality to Mesh struct in utilities.hpp
  • added uint3 resolution(float3 box_aspect_ratio, uint memory) function to compute simulation box resolution based on box aspect ratio and VRAM occupation in MB
  • added bool lbm.graphics.next_frame(...) function to export images for a specified video length in the main_setup compute loop
  • added VIS_... macros to ease setting visualization modes in headless graphics mode in lbm.graphics.visualization_modes
  • simulation box dimensions are now automatically made equally divisible by domains for multi-GPU simulations
  • fixed Info/Warning/Error message formatting for loading files and made Info/Warning/Error message labels colored
  • added Ahmed body setup as an example on how body forces and drag coefficient are computed
  • added Cessna 172 and Bell 222 setups to showcase loading composite .stl geometries and revoxelization of moving parts
  • added optional semi-transparent rendering mode (#define GRAPHICS_TRANSPARENCY 0.7f in defines.hpp)
  • fixed flickering of streamline visualization in interactive graphics
  • improved smooth positioning of streamlines in slice mode
  • fixed bug where mass and massex in SURFACE extension were also allocated in CPU RAM (not required)
  • fixed bug in Q-criterion rendering of halo data in multi-GPU mode, reduced gap width between domains
  • removed shared memory optimization from mesh voxelization kernel, as it crashes on Nvidia GPUs with new GPU drivers and is incompatible with old OpenCL 1.0 GPUs
  • fixed raytracing attenuation color when no surface is at the simulation box walls with periodic boundaries
• v2.9 (31.07.2023) changes (multithreading)
  • added cross-platform parallel_for implementation in utilities.hpp using std::threads
  • significantly (>4x) faster simulation startup with multithreaded geometry initialization and sanity checks
  • faster calculate_force_on_object() and calculate_torque_on_object() functions with multithreading
  • added total