Flow simulator

See how two circulation pumps move the water in your tank. Set the height of each pump and its distance from the front glass, choose a flow mode and watch where the jets meet and where the water stands still.

An empty tank 150 cm long, 60 cm water height and 60 cm deep, with a circulation pump on each side glass. Pump A sits 20 cm below the surface and 15 cm from the front glass, pump B 25 cm below the surface and 45 cm from the front glass.

Front view

height of the pumps

Top view

distance from the front glass, front glass at the bottom
Pump A–
Pump B–
Avg. speed–
Still water–

Pump output, last 40 seconds

Pump A (left)Pump B (right)
05102040+

Flow speed in cm/s (indicative). “Still” means less than 3 cm/s on average over 10 s. Average speed and still water apply to both views together.

What this simulation does and doesn’t show

These are two 2D flow models of the same tank: the front view shows the effect of the height of each pump, the top view the effect of its distance from the front glass. Both show how the flow behaves in each mode, where the jets meet and where the water stands still.

  • Tip: place the pumps at a different distance from the front glass. The jets then run past each other and create a circular flow, instead of colliding head-on.
  • The modes are imitations. Manufacturers don’t publish the exact wave forms of their flow modes. Pulse length, randomness and tidal cycle are reconstructed from their descriptions.
  • Two separate slices. The views are calculated separately. The front view doesn’t show flow towards the front or back, the top view doesn’t show flow up or down. A real jet fans out wider in 3D and loses speed faster.
  • No waves. The water surface is kept flat. The wave action that the Long bursts mode can build up in a real tank only shows here as flow moving back and forth.
  • Speeds are relative. 100% corresponds to about 80 cm/s at the pump.