** Laminar Flow vs Turbulent Flow **

Fluid Dynamics is an important part of classical physics, and the applications run from irrigation to human physiology. It has significant engineering contributions in the fields of aerospace, marine, irrigation, hydraulic and many other disciplines.

The fluid flow varies from one state to another, and for ease of analysis, flow is categorized into different regimes where the fluid properties such as velocity, pressure, density, and viscosity characterizes each regime. Turbulent and the Laminar flow are the two main classes of flow regimes.

**What is Laminar Flow?**

When the fluid particles flow without intersecting the paths of each other and the velocity of the particle is always tangential to the path of the particle, the flow is said to be streamline. When the streamline flow occurs, the layers of fluid particles tend to slide over the adjacent particle without disturbing the motion of others, and this occurs in layers or laminas of fluid flow. Such a flow is known as a Laminar flow. Laminar flow or streamline flow occurs when the fluid velocity is relatively low.

In laminar flow, the layer in contact with a stationary surface has zero velocity and, in the direction perpendicular to the surface, the velocity of the layers tends to increase. Also, the velocity, pressure, density, and other fluid dynamic properties remain unchanged at every point in the space of the flow.

The Reynolds number is an indication how good a fluid may undergo laminar flow. When the Reynolds number is low, the flow tends to be laminar, and the viscous forces are the dominant form of interaction between the layers. When the Reynolds number is high, the flow tends to be turbulent, and inertial forces are the dominant form of interaction between the layers.

**What is Turbulent Flow?**

When the fluid properties in a flow vary rapidly with time, i.e. when the changes in the velocity, pressure, density, and other flow properties show random and arbitrary changes, the flow is known as a turbulent flow.

The fluid flow within a uniform cylindrical pipe with a finite length, also known as a Poiseuille flow, will have turbulence in the flow when the Reynolds number reaches the critical number 2040. However, generally, the flow may not explicitly be turbulent when the Reynolds number is more than 10000.

A turbulent flow is characterized by its random nature, diffusivity, and vorticity. The flow contains eddies, cross currents and vortices.

**What is the difference between Laminar and Turbulent Flow?**

• In laminar flow, the flow occurs at low velocities and low Reynolds number, while turbulence flow occurs at high velocities and high Reynolds number.

• In Laminar flow, the path of the fluid lines is regular and streamline where there is no lateral disturbance of the fluid paths and the fluid flows in layers. In turbulent flow, the flow pattern is irregular and chaotic, where vortices, eddies, and cross currents occur.

• In laminar flow, the fluid properties at a point in space remain constant with time while, in turbulent flow, the fluid properties at a point are stochastic.

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