With Eevee you are now able to create beautiful realtime streams.

Paint your flow directly in Blender.

By using a Black and white image, or a Noise piped through a Color ramp, you can achieve almost realistic looking flow just with a shader. It's damn fast once it's compiled.

The Shader performs great in cycles too. Using the fantastic D-Noise Add On you can easily render at 2 samples a frame and have your preview within the time it takes going to lunch.