The Surface Flow is an audio-reactive Geometry Nodes setup that generates a point-based particle system constrained to a custom mesh. The particles are distributed using noise and feature rotation driven by audio values. The setup functions as a basic simulation and is designed primarily as a concept demonstration for study. The node trees are kept expanded and feature detailed explanations rather than being compressed into grouped assets, allowing users to read and dissect the core mechanics. The package includes three variations: Cube, Rotating Hemispheres, and Rotating and Stretching Hemispheres. It is optimized for EEVEE viewport rendering but can be adapted to other render engines.