Fluid Mechanics Practice Test: Viscous Flow & Turbulent Flow — Flashcards

Viscous Flow & Turbulent Flow topics include: Shear stress in viscous and turbulent flow, piston movement, flow of viscous fluid through circular pipes, power absorption, universal velocity distribution and viscosity coefficient methods.

Viscous flow can be laminar or turbulent. The difference between the two is the Reynolds number:
Laminar flow: Occurs when the Reynolds number is less than 2,300. Viscous forces are dominant, and the fluid moves smoothly and constantly.
Turbulent flow: Occurs when the Reynolds number is greater than 3,500. Inertial forces are dominant, and the fluid moves chaotically, with eddies and vortices. 

Here are some other characteristics of laminar and turbulent flow:
Laminar flow: The fluid moves in layers that don't mix.
Turbulent flow: The fluid moves with eddies and swirls that mix the layers together.
Viscous force: More prominent in laminar flow due to the slower flow rate.
Inertial force: Maximizes in turbulent flow due to the faster and irregular flow path. 

An example of turbulent flow is smoke coming out of a car's exhaust pipe. The smoke particles mix together and flow in a random zig-zag pattern.