2D Incompressible Fluid Simulation

Implementation of
Chapter 38. Fast Fluid Dynamics Simulation on the GPU

About The Project

The following code simulates a 2D Incompressible Fluid using an:

• Eulerian-Grid Scheme

• Semi-lagrangian Advection Method [Unconditionally Stable]

• System-of-Equations Jacobi Method Solver [Very easy to implement GPGPU]

• Central Difference for Approximating Calculus Operators [O(x^2) Error]

• Essentially All methods here are references to the original work of Stam1999 - stable fluids
  Here is a wikipedia article describing the method of solution

The currently most-updated revision 29cleanup3/ features the following:

• Force/Dye/Force-Dye User-Simulation Interaction
• Vorticity Confinement with variable coefficient
• Variable Kinematic Viscosity, Delta Time & Poisson-Solver Iterations
• Real-Time CFL/Reynolds Number Calculations (they're there to check solver correctness/stability)
• Visualizations of Calculation Textures, in particular Velocity-Pressure/Dye/Curl/Absolute Curl/Velocity Error/Pressure Error/Velocity-X/Velocity-Y/Pressure/CFL
• Real-Time Measurements of internal solver components - CPU & GPU Side:

  • A GPU Timer (gl-Begin/End-Query) essentially acts as a fence,
    waiting for all previous GPU commands to finish
    In Short: Using GPU Timers degrades Performance by a few milliseconds

  • When GPU Timers are not used, the calculations will be deferred until glfwSwapbuffers(), which by then will be dispatched & computed, updating glMemoryBarrier

Pretty Pictures

Tomorrow, Im Tired lol :)

Project Structure

The Underlying Project Structure uses my premake5-workspace-template repo,
You can expect the program/ folder to occupy all revisions of the fluid-solver,
culminating eventually with 29cleanup3/ as the currently best revision

Built With

                                 

Getting Started

Prerequisites - Instructions below work too, but you should follow premake5-workspace-template

• premake
• Working compiler toolchain, preferably clang
  • Windows: You should use llvm
  • Linux:
    1. installing-specific-llvm-version
    2. configuring-symlinks
    3. You Don't have to use LLVM, gcc works too
  • Define these environment variables (in your PATH):
    • LLVMInstallDir
    • LLVMToolsVersion
• Powershell / Any Standard unix-shell

Installation

Just Clone the repo

Usage

Build Process

premake5 --os=windows --arch=x86_64 --cc=clang gmake2
premake5 --os=windows --arch=x86_64 --cc=clang vs2022
premake5 --os=linux   --arch=x86_64 --cc=gcc   gmake2
premake5 --os=linux   --arch=x86_64 --cc=clang gmake2

You can also use this command to perform the whole build process,
if youre using gmake2 and a commandline:

premake5 --os=windows/linux --arch=x86_64 buildallrel

Dont forget to actually build using your favorite IDE/command-line utility

Execution

Static Library Builds: (premake5 gmake2, config=releaselib_amd64)

./build/bin/ReleaseLib_amd64_program/program

DLL/Shared Library Builds: (premake5 gmake2, config=releasedll_amd64)

./build/bin/ReleaseDll_amd64/program

Visual Studio 2022 - Just Run normally using Local Windows Debugger

Roadmap

• Replacing Jacobi Method with the Multigrid Method for better performance & faster fluid convergence
• Adding Arbitrary boundaries
• Extending to 3D
• MAC Staggered Grid
• Different Simulation Schemes (FVM, etc...) for better simulation accuracy
• Extending to compressible/Turbulent Models

Contributing

If you have a suggestion, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement".

License

Distributed under the MIT License. See LICENSE file for more information.

Acknowledgements

• Kumodatsu For the initial template repo
• Jarod42 For the Improvements branch of export-compile-commands
• Best-README

References

• Fluid Mechanics 101
• GPU Gems 38
• Stable Fluids - Stam 1999
• Colour Advice
• Computational Methods for Fluid Dynamics - Fourth Edition (Ferziger, Perić, L. Street)
• Online PDF of the Above Book