What happens at low Reynolds number?
laminar flow occurs at low Reynolds numbers, where viscous forces are dominant, and is characterized by smooth, constant fluid motion; turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilities.
Why do the flows become turbulent at high Reynolds numbers?
The viscous regions in high Reynolds number flows are dominated by turbulence. Instability in the shear layer creates turbulent fluctuations of flow-field properties. That is why these models did not become famous for predicting flows involving shear and mixing layers and detached flows.
How is flow described using the Reynolds number?
The Reynolds number, referred to as Re, is used to determine whether the fluid flow is laminar or turbulent. Technically speaking, the Reynolds number is the ratio of the inertial forces to the viscous forces. This ratio helps to categorize laminar flows from the turbulent ones.
Why does flow become turbulent?
Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid’s viscosity. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases.
What is the importance of the Reynolds number in turbulence?
Turbulent or laminar flow is determined by the dimensionless Reynolds Number. The Reynolds number is important in analyzing any type of flow when there is substantial velocity gradient (i.e. shear.) It indicates the relative significance of the viscous effect compared to the inertia effect.
What is the formula for Reynolds number?
Reynolds Number = Inertial Force / Viscous Force. The Reynolds number formula is expressed by, Where, ρ = density of the fluid, V = velocity of the fluid, μ = viscosity of fluid, L = length or diameter of the fluid.
What rate is needed for turbulent flow?
The minimum flow rate of water to achieve fully turbulent flow in this tubular system is 0.765 kg/s or about 12 GPM. Thanks to everyone who submitted an answer, including Trent Benanti and Bob McGurk!
What is the SI unit of the Reynolds number?
A similar equation for the Reynolds number in SI units is (5.18)R = 353,678 Q / (νD)