I'll create a self-contained HTML file with a real-time fluid simulation that responds to mouse dragging. The simulation will show colored dye swirling through the fluid as you drag your mouse.

I've created a complete fluid simulation web app in a single index.html file. The simulation features: 1. A full-screen canvas that adapts to window size 2. Real-time fluid dynamics with velocity fields and density propagation 3. Mouse/touch interaction - dragging your mouse pushes swirling colored dye through the fluid 4. Multiple colors that mix as the fluid moves 5. No external resources - everything is self-contained in the HTML file To use it: - Open the index.html file in any modern browser - Click and drag your mouse across the screen to create colorful swirling patterns - The fluid will continue to flow and mix even after you release the mouse - Works on both desktop and mobile devices (touch support included) The simulation uses a grid-based fluid dynamics model with diffusion, advection, and projection steps to create realistic fluid behavior. The colored dye is added at your mouse position and is carried by the fluid velocity field, creating beautiful swirling patterns.