This example animates a sequence of 15 circles whose vertical positions and radii oscillate over time, creating a fluid wave-like motion. The circles are generated procedurally using sine functions, with each frame updating their `cx`, `cy`, and `r` attributes. The visualization uses D3.js v6 and its `select`, `range`, and `join` APIs to render the dynamic scene as an SVG, with an animation loop driven by `setInterval`. The data is recalculated in `makeData` and passed to `vizData` via the `svg.call` method.