CFD Solver Library 🌊

A specialized Python library for calculating fundamental flows in Computational Fluid Dynamics (CFD). Designed to be easy to learn while remaining numerically robust and suitable for educational and research purposes.

🎯 Key Features

Feature	Description
Educational	Clear implementations of FDM, SOR, and Upwind schemes
Robust	Comprehensive logging and error handling for numerical stability
Non-Newtonian	Support for Power-Law fluids (shear-thinning/thickening)
Visual	Built-in plotting and easy animation workflows
Verified	All solvers verified against analytical solutions

🔧 Capabilities

1. Newtonian Poiseuille Flow

Classic pressure-driven laminar flows:

• Plane Poiseuille: Flow between parallel plates
• Circular Poiseuille: Flow in circular pipes
• Features: SOR solver, analytical verification, convergence tracking

2. Non-Newtonian Flow ✨

Power-Law model for variable viscosity fluids:

• Shear-thinning ($n < 1$): blood, paint
• Newtonian ($n = 1$): water
• Shear-thickening ($n > 1$): cornstarch suspension
• Features: Non-linear iterative solver with robust stability controls

3. Lid-Driven Cavity Flow

Benchmark 2D Navier-Stokes solver:

• Physics: Incompressible, viscous flow in square cavity
• Stability: Upwind differencing, dynamic time-stepping, numerical clipping
• Outputs: Velocity field, pressure distribution, vorticity analysis
• Animation: Frame generation for video creation

🛠 Installation

Stable Release (Recommended for Users)

You can install cfd-solver directly from PyPI using pip:

pip install cfd-solver

Development Version (For Contributors)

If you wish to contribute to the project or use the latest development features, you can install it from source. We recommend using uv for dependency management during development:

1. Clone the repository:

   git clone https://github.com/hardwork9047/cfd-solver.git
   cd cfd-solver
   

2. Install dependencies with uv:

   uv sync
   

   This will install all necessary development and runtime dependencies.

Quick Start Example

Here's a quick way to get started with a simple Plane Poiseuille flow simulation:

import matplotlib.pyplot as plt
from cfd import PlanePoiseuille

# Initialize the solver for a plane Poiseuille flow
# (distance between plates, pressure gradient, viscosity)
flow = PlanePoiseuille(L=0.01, dp_dx=-100, mu=1e-3, ny=51)

# Get analytical solution
u_analytical = flow.analytical_solution()

# Get numerical solution
u_numerical = flow.numerical_solution()

# Plot the velocity profile
plt.figure(figsize=(8, 5))
plt.plot(u_analytical, flow.y, label='Analytical Solution')
plt.plot(u_numerical, flow.y, 'o', markersize=4, fillstyle='none', label='Numerical Solution')
plt.xlabel('Velocity (m/s)')
plt.ylabel('Position (m)')
plt.title('Plane Poiseuille Flow')
plt.legend()
plt.grid(True)
plt.show()

� Numerical Methods

To ensure robust and accurate simulations, this library implements:

• FDM (Finite Difference Method): 2nd-order central difference for diffusion
• Upwind Scheme: 1st-order upwind for stable advection
• SOR (Successive Over-Relaxation): Accelerated iterative solver
• Dynamic Time-Stepping: Automatic adjustment based on CFL and viscous stability limits

📂 Project Structure

cfd/
├── src/cfd/
│   ├── poiseuille.py       # SOR-based Newtonian solvers
│   ├── cavity.py           # Stabilized Navier-Stokes solver
│   └── non_newtonian.py    # Power-Law fluid solvers
├── examples/
│   ├── verify_*.py         # Rigorous verification scripts
│   ├── demo_*.py           # Feature demonstrations
│   └── make_animation_frames.py   # Animation frame generator
├── docs/
│   ├── VERIFICATION_REPORT.md  # Test results and performance
│   └── VIDEO_TUTORIAL.md       # Animation creation guide
└── TUTORIAL.md             # Step-by-step learning path

📖 Documentation

• TUTORIAL.md: Step-by-step learning path for beginners
• docs/VERIFICATION_REPORT.md: Detailed verification results and performance metrics
• docs/VIDEO_TUTORIAL.md: Guide to creating animations with FFmpeg

🚀 Quick Demo

Want to see something cool right now? Try running the Lid-Driven Cavity demo:

uv run python examples/demo.py

Or see how a shear-thinning fluid flows:

uv run python examples/demo_shear_thinning.py

🔒 Engineering Standards

This library follows high standards for your safety and success:

• Python 3.11+
• Robust Error Handling (No more silent NaNs!)
• Comprehensive Logging
• Strict Analytical Verification
• Test Coverage: 15+ tests, all passing ✅

🤝 Contributing

We welcome contributions! Please see our CONTRIBUTING.md for guidelines on how to get started.

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

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Created with care to help you master the world of fluids. 🌊