Streamline and Turbulent Flow

Streamline and Turbulent Flow

Streamline and Turbulent Flow: When shear stress acts on a liquid or fluid, it moves. This shear stress or force is acting parallel to the liquid’s surface. In the case of a flowing stream, the earth’s gravitational force is acting on it and pulling it down.

Streamflow is defined by the path of a single atom in a fluid and is classified into two types: streamline flow and turbulent flow.

A steady, smooth, and predictable flow is referred to as a streamlined flow. A turbulent flow occurs when the flow of a stream is marked by chaotic changes.

A streamlined flow, also known as a laminar flow, has no significant velocity fluctuations. A streamline is a path of imaginary particles carried along with the fluid. The streamlines are fixed in a constant flow, and the fluid follows a smooth and regular path.

This means that the flow properties such as velocity, pressure, and so on remain constant at each point. Consider laminar flow, which consists of laminae or thin layers that are all parallel to each other. In a streamlined motion, these layers of water flow at different speeds on top of each other, with no mixing between them.

A turbulent motion in a fluid is defined as an irregular motion caused by either high velocities or abrupt changes in velocities. It’s unlikely because there’s water all around and the ball could go in any direction at any time.

It is similar to the turbulent flow of fluids, in which the motions of the fluid particles are random and unpredictable. The fluid does not pass in parallel layers in a turbulent flow, and there is a high level of lateral mixing and disruption between layers.

There is a continuous change in magnitude and direction of flow at any given point in the fluid that is undergoing turbulent flow. Blood flow in our bodies is typically streamlined or laminar. However, in high flow conditions, laminar flow can be disrupted, resulting in a turbulent flow. At the branch points of large arteries, the flow is also turbulent.

Overview: Streamline and Turbulent Flow

Streamline flow in fluids is defined as the flow of fluids in parallel layers with no disruption or intermixing and the velocity of each fluid particle passing by remaining constant with time at a given point. There are no turbulent velocity fluctuations at low fluid velocities, and the fluid tends to flow without lateral mixing.

The fluid particles move in a specific order relative to the particles moving in a straight line parallel to the pipe wall, causing adjacent layers to slide past each other like playing cards.

The motion of liquid particles becomes chaotic or irregular when it goes faster than its critical velocity. A turbulent flow is a name for this type of flow. The path and velocity of the liquid particles change continuously and haphazardly from point to point in a turbulent flow.

In a turbulent flow, the majority of the external energy used to keep the flow going is spent producing eddies in the liquid, leaving only a small fraction of energy available for forwarding flow. Eddies, for example, can be seen by the sides of the pillars of a river bridge.

 

Streamline in fluid mechanics:

The path of imaginary particles suspended in fluid and carried along with it in fluid mechanics. The fluid is moving in a steady flow, but the streamlines are fixed. The fluid speed is relatively high where streamlines crowd together; relatively still where they open out. Streamline flow (also known as flow) is a type of fluid flow in which the fluid travels in regular paths. The velocity, pressure, and other fluid properties remain constant at each point in a streamlined flow.

When the velocity of every particle in the fluid is constant over time, the flow is steady. This statement, however, does not imply that the velocity of fluid particles will not vary at different points in space. The velocity of a fluid particle can change as it moves from one point to another.

This means that the particle’s velocity can vary depending on where it is. The term “steady flow” denotes that each particle passing through the second point will behave in the same way as the previous fluid particle that passed through that point. As a result, in a steady-flow condition, the fluid particles will follow a smooth path that does not cross each other.

As a result, a streamline is a path taken by fluid particles in a steady flow condition. The tangent drawn at any point of the curve (path) in a streamlined flow will be in the direction of the fluid’s velocity at that point.

Define streamline flow:

Streamline flow in fluids is defined as the flow of fluids in parallel layers such that there is no disruption or intermixing of the layers and the velocity of each fluid particle passing by remains constant with time at a given point.

There are no turbulent velocity fluctuations here at low fluid velocities, and the fluid tends to flow without lateral mixing. The fluid particles move in a specific order with respect to the particles moving in a straight line parallel to the pipe wall, so that the adjacent layers slide past each other like playing cards.

Streamline flow occurs in pipes (or tubes) when a fluid flows in parallel layers with no interruption between them. At low speeds, the fluid flows without lateral combining, and adjacent layers slide past each other like playing cards. There are no cross-currents perpendicular to the fluid flow direction.

According to streamline flow, the fluid particle movement is always in order, with other particles moving in a parallel line to the pipe walls. Any lateral combining (mixing at right angles to the flow direction) occurs due to the action of diffusion between liquid layers. Diffusion combination is slow, but if the diameter of the pipe or tube is small, this diffusing combination will work.

Turbulent boundary layer:

A boundary layer can be either laminar or turbulent in nature. A laminar boundary layer is one in which the flow occurs in layers, with each layer sliding past the adjacent layers. This is in contrast to the Turbulent Boundary Layers which are highly agitated.

Any exchange of mass or momentum in a laminar boundary layer occurs only between adjacent layers on a microscopic scale that is not visible to the naked eye. As a result, the shear stress associated with molecular viscosity can be predicted. Laminar boundary layers can only be found when the Reynolds numbers are low.

 

A turbulent boundary layer, on the other hand, is distinguished by mixing across multiple layers. The mixing has now reached a macroscopic level. Fluid packets can be seen moving across. As a result, mass, momentum, and energy are exchanged on a much larger scale than in a laminar boundary layer.

Only at higher Reynolds numbers does a turbulent boundary layer form. Molecular viscosity alone cannot handle the scale of mixing. Turbulence Viscosity or Eddy Viscosity, which has no exact expression, is used to calculate turbulent flow. It must be modelled. For this purpose, several models have been developed.

Streamline flow, also known as laminar flow, is an uninterrupted flow (as of air) past a solid body in which the direction at every point remains constant over time. Streamline flow is a type of fluid flow that follows a set path. As a result, we can say that layers of water move smoothly from one end of the pipe to the other. So, when you look at a flowing stream, you first notice a few things about it, such as the speed of the water in it, its width, the amount of water flowing, and so on. One of the primary characteristics of a stream is its flow, also known as streamflow. This page discusses the streamlined flow, as well as its various applications.

Also read: Important Topic of Physics: Ampere

FAQs on (Streamline and Turbulent Flow)

Question: What are the properties that all fluids share?

Answer: Despite the fact that each fluid is unique in terms of composition and specific properties, there are a few characteristics that all fluids share.

These characteristics are classified as follows:

• Kinematic properties: These characteristics aid in the comprehension of fluid motion.
• Fluid velocity and acceleration are kinematic properties.
• Thermodynamic properties: A fluid’s thermodynamic state is determined by its thermodynamic properties. Fluid thermodynamic properties include temperature, density, pressure, and specific enthalpy.

Physical properties: These characteristics, such as colour and odour, aid in determining the physical condition of the fluid.

Question: What is meant by Viscosity?

Answer: Viscosity is the resistance of a fluid to change its form, or the resistance of relative movement of sections close to each other in a fluid. In other words, viscosity is the inverse of flow. Fluidity, the polar opposite of viscosity, measures the ease of flow.

Honey, for example, has a much higher density than water. Internal friction between molecules in a fluid can be viewed as a stumbling block to the formation of velocity differences. One of the most important factors in determining the forces that must be overcome in order for fluid to be delivered through pipes is the viscosity of the fluids used in lubrication. In operations such as spraying and surface coating, viscosity regulates fluid flow.