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In fluid dynamics a flow in which liquid undergoes chaos and fluctuations or mixing is called turbulent flow. It lies parallel with the laminar 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. In turbulent flow, Fluid does not flow in streamlines, rather it is a random disruptive flow. The calculations involving turbulent flow are very complex.
EXAMPLES OF TURBULENT FLOW
We can observe turbulent flow in the following events:
- The motion of wind around air-craft
- Lava flow
- The flow through pumps and turbines
- Air or water swirls
- Billowing storm clouds
- Smoke
- Air from fan/ac
The turbulence can be felt and measured by using the Reynolds number. George Stokes coined the concept of Reynolds number in 1851. It is considered to be a 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 is 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
The formula for the Reynolds number could be written as: Re= vD
Where,
= Density of fluid
v = Velocity of fluid
μ = Viscosity of fluid
D = Diameter of the fluid.
Based on the different values of Re, we can infer that:
- If Re < 2000, the flow is called Laminar
- If 2000 < Re < 4000, the flow is called transition.
- If Re > 4000, the flow is called turbulent
EXAMPLES OF TURBULENCES
The following depicts the turbulences in real-life events:
- Smoke rising from a cigarette. For the initial few centimetres, the smoke shows features of laminar flow, but after rising, it changes to turbulent flow.
- Flow over the golf ball.
- Clear air turbulence is usually experienced during flight take-offs.
- Oceanic and mixed atmospheric layers, along with strong oceanic currents.
- Flow of blood through arteries during heart conditions
- Piers in water as water moves softly around the legs while the river’s flow is soft.
LAMINAR AND TURBULENT FLOW
The difference between laminar and turbulent flow could be understood with the following:
S.no | LAMINAR FLOW | TURBULENT FLOW |
1. | In this fluid flow, the fluid layers move parallel and never meet each other and never tend not to cross each other. | In this flow of 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 order, 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 order, 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.
ONSET OF TURBULENCE?
The Reynolds number could easily predict the onset of turbulence. 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 is the Reynolds number, the more it has a laminar flow, and as the number hikes up, the flow becomes turbulent.
CONCLUSION
From the above-stated theory, we learned about the two types of flows, the laminar flow, and the turbulent flow. The turbulent flow is in which liquid undergoes chaos and fluctuations or mixing. It lies parallel with the laminar flow, in which layers of fluid move without any disruption and smoothly. We understood the flows with live examples that we experience in day-to-day life. The differences between the two flows gave us more clarity two. We also understood how the two flows are part of the Reynolds number and the practical formula to calculate the laminar and turbulent flow in fluids.
