The Art and Science of Home-based Small Wind Tunnel Testing: The Beautiful Flow Physics
August 24, 2025
This week I used a small wind tunnel @ home to visualize airflow with smoke — one of the most beautiful sights. I ran the flow over a tiny die‑cast car, with the wheels actually turning, and performed Optical flow to get velocity vectors and SINDy analysis. It was just for fun, not a professional setup — no camera stabilization and no masking. Watch the full video below!
The Equipment Breakdown
- 💨Small smoke flow visualization wind tunnel (Fun-Tech-Lab
https://fun-tech-lab.com
Fun-Tech-Lab) - 🏎️ 1:64 scale car model with rotating wheels
- 📷 Sony A7III camera with manual focus for high-quality capture
- 💻 DaVinci Resolve for video processing (tool used for editing Oppenheimer, Top Gun: Maverick, Solo: A Star Wars Story) (https://www.blackmagicdesign.com/products/davinciresolve)
- 📏 Calibration: ruler/marker in frame to convert pixels to measurement values (using https://turbulencerealm.com/)
- 🧮 Optical flow algorithms for vector extraction (using https://turbulencerealm.com/)
- 🔬 SINDy (Sparse Identification of Nonlinear Dynamics) for for training and predictions (using https://turbulencerealm.com/)
Why small wind tunnels are awesome (even when they’re imperfect)
- 🚀 Rapid iteration: quick setups, instant visual feedback, and low risk if you mess up.
- 💸 Budget-friendly: simple smoke visualization and a consumer camera can go far.
- 🎥 Intuitive: smoke reveals separation, reattachment, shear layers, and wakes in a visceral way.
- 🧠 Teachable: perfect for building intuition before you chase coefficients or full-scale fidelity.
- ⚠️ Caveat: Great for qualitative insight, not absolute numbers.
The Process: From Visualization to Prediction
Stage 1: Flow Visualization
Scale model in the wind tunnel and introduced smoke to make the otherwise invisible air currents visible. The rotating wheels added an extra dimension of realism to the test, simulating actual driving conditions.
Stage 2: High-Quality Capture
Using my Sony A7III with manual focus, I recorded the smoke patterns as they flowed around the vehicle. The camera’s excellent low-light performance and resolution helped in capturing the flow. I would recommend professional high-speed monochrome cameras and lenses for professional use.
Stage 3: Video Processing
After capturing the footage, I imported it into DaVinci Resolve for processing. The software’s powerful color grading capabilities helped enhance the contrast between the smoke and background, making flow patterns more distinct.
Stage 4: Vector Extraction
I used optical flow algorithms to extract velocity vectors from the video. These vectors represent the direction and magnitude of air movement around the car model at each point.
Stage 5: Mathematical Modeling
The final step involved applying SINDy (Sparse Identification of Nonlinear Dynamics) to the extracted data. The mathematical technique helped identify the underlying equations governing the flow (as a dynamical system)and make predictions about how the air would behave under different conditions.
Note: Try to start from 10 seconds of video (10 sec x 30 fps = 300 frames) to perform processing depending on you computer’s memory.
Interesting things
- 🌪️ Vortex formation and flow physics in different parts of the car as expected
- 💨 The rotating wheels created interesting effects
- 📊 SINDy successfully predicted flow patterns that matched visual observations (with errors)
- 🔍 Small-scale testing can reveal insights applicable to full-size vehicles
The beauty of this experiment is that it demonstrates how accessible advanced fluid dynamics testing has become — you don’t need a multi-million dollar facility to explore the basics of aerodynamics.
Try It Yourself
If you’re interested in conducting similar experiments, you don’t necessarily need all the equipment I used. Start simple with a simple setup and a good camera. The physics remains fascinating at any level of sophistication!
Final Thoughts
It’s a reminder that with today’s technology, the gap between professional research and hobbyist exploration continues to narrow. Whether you’re a seasoned engineer or just someone who loves tinkering, there’s never been a better time to explore the invisible forces that shape our world.