https://crgimenes.itch.io/kutta
kutta streams a flow past an airfoil and draws the speed field, vorticity, smoke streaklines and the lift/drag vectors while you turn the angle of attack. Draw your own shape, cut a wing into wing + flap, animate the control surfaces, and watch the wake fall apart when you push the angle too far.
It is qualitative, not validated CFD: it gets the shape of the flow right and the numbers wrong, on purpose. Use it for intuition, for teaching, or just for poking at air.
It runs in the browser right on the page. Desktop builds for Windows, macOS and Linux are one file each, no installer, pay what you want (zero included).