Question

What are the two main causes of turbulent flow?

Answer 1

1. Turbulence is produced by a barrier or sharp edge, like the tap, which imparts velocities perpendicular to the flow.
2. A fluid flow becomes unstable or extremely disordered if its velocity in relation to a solid body is increased beyond a specific critical velocity. Both times, secondary motions split up the orderly streamlines into eddies or vortices, which causes turbulence. The fluid particles cross and recross the main direction of flow continually.