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STREAMLINE FLOW

Let us learn about streamlined flow in fluids and their properties—how it is measured and its factors.

DEFINE STREAMLINE FLOW

Streamline flow, also known as laminar flow, occurs in fluid substances. It is described as a flow where there is no mixing of layers, no turbulence, and no fluctuations in the velocity of the fluid particles, all of them remain constant. In contrast, to streamline flow, another flow is known as turbulent flow. Turbulent flow is when liquid undergoes chaos and fluctuations or mixing. It lies parallel with the laminar or streamline flow, in which layers of fluid move without any disruption and smoothly. In the turbulent flow, the fluid receives disruptions due to changes in pressure and velocity.

WHAT ARE STREAMLINES?

Streamlines are defined as directly elected by the particles of the fluids below constant flow circumstances. If we constitute the flow lines with curves, Then the tangent drawn from any point on the curve tells us about the direction of the fluid velocity at the point given to us.

EXAMPLES OF STREAMLINED FLOW

Blood flow in veins
Water coming out from a tap
Smoke coming out from a cigarette till few centimeters
Water fountains placed in gardens
Flow in rivers and canals
Flow in water balloons
Aircraft flying at a constant speed
Viscous fluid like honey

STREAMLINE IN FLUID MECHANICS

The concept of laminar or streamlined flow is vastly used in fluid mechanics, science. Streamline in fluid mechanics is used to measure turbulence intensity at a given point in time. The term laminar or streamline flow could be used in Reynolds number, which helps us calculate the velocity of fluids.

George Stokes coined the concept of the Reynolds number in 1851. It is considered to be the source that assists us to predict the different flow patterns in numerous fluids. It is yielded to be a ratio of inertial forces to viscous forces. The lower the Reynolds number, the more it has a laminar flow, and as the number hikes up, the flow becomes turbulent.

Reynolds number is a very renowned concept in the field of science as it helps to calculate the following:

Water flowing through the pipe
Air present in the valve

REYNOLDS NUMBER FORMULA

The formula for the Reynolds number could be written as:

Re= ρ V L\mμ

Where,

ρ = density of fluid

V = velocity of fluid

μ = viscosity of fluid

L = length or diameter of the fluid.

Based on the different values of Re, we can infer that:

If Re < 2000, the flow is called Laminar
If Re > 4000, the flow is called turbulent
If 2000 < Re < 4000, the flow is called transition.

REYNOLDS NUMBER UNITS

The variables in Reynolds number possess different units. These are as follows:

R in the Reynolds number is unitless
ρ in the fluid density is taken in kilograms-per-cubic-meter (kg/m3)
v in the velocity is taken in meters-per-second (m/s)
D in the diameter of the pipe is always in meters (m)
μ in the viscosity of the fluid is taken in pascal-seconds (Pa⋅s)

STREAMLINE AND TURBULENT FLOW

The difference between streamline and turbulent flow could be understood with the following:

S.no	STREAMLINE FLOW	TURBULENT FLOW
1.	In this fluid flow, the fluid layers move parallel and never tend to meet and cross each other	In this fluid flow, the fluid layers tend to cross each other and never move parallel to each other, and may meet at some point.
2.	This flow is evident in the fluids that flow with low velocity.	This flow is evident in the fluids that flow with high velocity.
3.	Laminar flow is experienced in the small diameter pipes where fluid flows with low velocity.	Turbulent flow is experienced in large diameter pipes where fluid flows with high velocity.
4.	The fluid flow is laminar when calculated Reynolds number (Re) is less than or equal to 2000.	The fluid flow is turbulent when the calculated Reynolds number is greater than or equal to 4000.
5.	The amount of stress in laminar flow lies in the viscosity of the fluid.	The amount of stress in the turbulent flow lies upon the density of the fluid.
6.	The fluid flow runs in an orderly manner, i.e., there is no mixing or meeting of side layers of the fluid, and they keep moving parallel to each other.	The fluid flow doesn’t run in an orderly, i.e. there is mixing and meeting of side layers at some point with each other, and they do not move parallel to each other.

LAMINAR AND TURBULENT BOUNDARY LAYERS

A boundary layer is defined as both laminar and turbulent. A laminar boundary layer is referred to when the flow is in different layers, i.e. when layers move smooth and glide over side layers. On the other hand, a turbulent boundary layer is inferred as one where the flow of layers keeps on mixing.

CONCLUSION

The whole article briefs us about the streamline flow that is the fluid mechanics and is seen in fluids. The concept of fluid mechanics is vastly used in the science field. Through the article, we learned about how to define the streamlining flow. We also understood the link between the Reynolds number and the two flows, the property exhibited by the streamline and turbulent flow. Streamline flow, also known as laminar flow, takes place in fluid substances. It is described as a flow where there is no mixing of layers, no turbulence, and no fluctuations in the velocity of the particles of the fluid, all of them remain constant. In contrast, to streamline flow, there exists another flow known as turbulent flow. Turbulent flow is a flow in which liquid undergoes chaos and fluctuations or mixing. It lies parallel with the laminar or streamline flow, in which layers of fluid move without any disruption and smoothly. In the turbulent flow, the fluid receives disruptions due to changes in pressure and velocity. We also understood the difference between the streamline and turbulent flow.