What is Reynolds number and its significant?

Question

I need to know what Reynolds number is, and when and how we use it. It is from fluid mechanics

Answer 1

reynold number is given by formula :
n=v*d*2r/eta
where v=velocity of flowing liquid ,d=density of liquid flowig,2r=diameter of tube in which liquid is flowing ,eta is viscosity of liquid
if reynold number is greater than 2000 than flow of liquid is said to be turbulent when its btw 0-2000 than flow of liquid is laminar

Answer 2

Re = ( rho * v * L ) / mu

where rho is the density of the fluid, v is the velocity of the fluid, L is a characteristic legnth, and mu is the fluid viscosity.

The Reynolds number is the ratio of inertial forces to viscous forces.

Laminar flow occurs at low Re #'s and turbulent flow occurs at higher Re #'s.

In modeling, to represent accurate flows, the reynolds numbers must match the model to the actual aircraft.

Answer 3

Reynolds number is one of many dimensionless entities used in fluid mechanics. It tells you whether your fluid is flowing in a turbulent or laminer regime. Turbulent flow is characterized by thinner boundary layers at the pipe walls, "good" mixing, and eddy currents. Laminar flow is layered flow. Thicker boundary layers, poorer mixing, no eddys. Values of Re<2100 are generally considered laminer. Values of Re>2100 are generally turbulent flow.

The concept behind Re is that it is the ratio of inertial forces of the fluid flowing to the viscous drag forces of the fluid. When drag forces are large compared to inertial forces, the fluid flows in a layered pattern. When inertial forces are >> drag forces, then fluid loses its layered flow pattern.

It is used predominantly by engineers designing fluid transfer systems to determine pressure drops, diameter of pipes, support requirements, and wear and tear on equipment.

In my career, (I am a ChE) I have designed many distribution systems and many mixing systems that have required Re to be calculated. Areospace engineers, which I am not, might use Re and other dimensionless entities to model air flow over aircraft fuselage and wings. Same thing for automotive engineers.

actual equations are

Re = rho * u * d / v

rho = fluid density
u = fluid "bulk" velocity
d = diameter of "pipe" fluid is flowing through
and v = viscosity of fluid

FYI. Calculating Re usually requires some excellent unit conversion skills. For example, density may be in g/cc, velocity in gpm, diameter in inches and viscosity in centipoise. Correctly calculating Re means the units all match up and cancel each other out. Re has no units.

Answer 4

generally it refers to laminal flow vs turbulant flow. The higher the reynolds number the more likely the flow is to be turbulant the lower it is the more likely it is to be laminar. look up the Formulas for the mathematics behind it.

Answer 5

because of the fact the diameter and bypass value is saved consistent, the reynold selection relies upon upon the coefficient of viscosity. i think of water has greater viscosity than liquid glycerine, so the reynold selection might shrink. If i'm incorrect, then it incredibly is vice-versa.