How to show air flow in pipes?


Does anyone have any suggestions on how to show that the air currents for example through a tube with different diameters and a few twists.
All suggestions are welcome, both of the simpler kind, and more advanced.

// Wilnix

Moving twisting arrows along a path might do it?

One very simple idea would be to animate a texture along the axis of a tube, for example if the tube is standing up move the texture along the Z axis. If you take this tube, segment it and use a curve modifier you could easily bend the tube in any way you need by editing the curve. You could also vary the width of the tube. This tube could then be duplicated and one of them sized to be the outside of the tube. Use a different texture on this part so it would appear to be the outer part with transparency likely. The inner tube would be your air flow texture. It would appear to flow along the direction and curves of the tube.

Granted this is theory based on using this same technique in another app. I can only guess it would work the same in Blender.