wtf is kutta?

Kutta is a 2D wind tunnel simulator for people who build model airplanes or who just enjoy watching air flow do interesting things. It streams simulated air past a wing shape and draws the speed field, the swirling vorticity, smoke trails, and the lift and drag forces as you change the angle of attack. You can also draw your own custom shape, split a wing into a wing plus a flap, animate those parts moving, and watch the airflow break apart when the angle gets too steep. The author is upfront that this is a qualitative tool, not a validated engineering simulation. It uses simplified lattice units rather than real physical units, so it gets the shape of the airflow right, such as where the air stagnates, where the wake forms, and where the flow separates as the angle increases, but the actual numbers should not be trusted. It is meant to build intuition and to look good on a projector screen, not to size a real aircraft wing. The program is written in Go using a game library called Ebitengine, and ships as a single executable with nothing else to install. It can be tried directly in a web browser through WebAssembly, though opening or saving scene files and importing SVG shapes only works in the downloaded desktop version. Prebuilt binaries are available for macOS, Windows, and Linux, so a person does not need to install Go or any developer tools to use it. On macOS it can also be installed with a single Homebrew command. Once open, arrow keys change the angle of attack, other keys switch between different views of the airflow such as pressure or streamlines, and a text field lets you type in any four or five digit NACA airfoil code to test different wing shapes. Pressing E opens an editor where a shape can be drawn by hand with a pen tool, or imported from an SVG file exported by programs like Inkscape or Illustrator, turning any silhouette, such as a car or a building, into something the tunnel can blow air over. Under the hood, the airflow itself is computed using a method called the Lattice Boltzmann method, a way of simulating fluid flow on a grid, while the wing shapes come from standard NACA airfoil formulas. The project includes a gallery of example scenes, including a simulation of a Ferrari rear wing, that can be loaded and explored the same way.