What happens during turbulent flow?

What happens during turbulent flow?

In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction. The flow of wind and rivers is generally turbulent in this sense, even if the currents are gentle. The air or water swirls and eddies while its overall bulk moves along a specific direction.

What causes turbulent flow in a fluid?

Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid’s viscosity. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases.

What causes turbulent viscosity?

The coefficient that relates the average shear stress and rate of velocity gradient in the turbulent flow is called turbulent viscosity. The viscosity in the turbulent flow is non- homogeneous, and it varies in space.

How does viscosity affect turbulent flow?

The greater the viscosity of a fluid, the greater the value of R. Turbulence greatly increases R, whereas increasing the diameter of a tube decreases R. If viscosity is zero, the fluid is frictionless and the resistance to flow is also zero.

What is meant by streamline and turbulent flow of a liquid?

Laminar flow or streamline flow in pipes (or tubes) occurs when a fluid flows in parallel layers, with no disruption between the layers. Turbulent flow is a flow regime characterized by chaotic property changes. This includes rapid variation of pressure and flow velocity in space and time.

How is turbulence created?

Turbulence is caused when an airplane flies through waves of air that are irregular or violent, which cause the aircraft to bounce around yawing, pitching, or rolling. These do not tell where there will be turbulence.

What is turbulent flow in a pipe?

Turbulent flow is a flow regime characterized by chaotic property changes. This includes rapid variation of pressure and flow velocity in space and time. In contrast to laminar flow the fluid no longer travels in layers and mixing across the tube is highly efficient.

How viscosity affects the flow through the fluid?

The short answer is; as viscosity increases, flow rates decrease. * As a general rule, the further the fluid is from the pump, the lower the flow rate will be.

How does turbulent flow differ from laminar flow for which flow is the heat transfer coefficient higher?

Under turbulent flow conditions, the increase in heat transfer rate is more significant than that under laminar flow conditions. This is due to the increase in the Reynolds number of the flowing fluid in turbulent flow. The turbulent effects become a dominant factor over secondary flow at higher Reynolds number.

How do laminar and turbulent flow differ?

Laminar Flow: the flow of a fluid when each particle of the fluid follows a smooth path, paths which never interfere with one another. One result of laminar flow is that the velocity of the fluid is constant at any point in the fluid. Turbulent Flow: irregular flow that is characterized by tiny whirlpool regions.

What happens to fluid in a turbulent flow?

Under such conditions, fluid elements do not remain confined to definite laminae, but rapid, radial mixing occurs ( Figure 6-12). A much greater pressure is required to force a given flow of fluid through the same tube when the flow is turbulent than when it is laminar.

When does turbulence not occur in a pipe?

However, if Re is less than 2300, the flow will be laminar even if it is disturbed. Thus 2300 is the value the Re below which turbulence will not occur in a pipe. Moreover, if the flow has a different geometry, such as flow in a square duct, or over a turbine blade, transition will occur at different values of Re.

How is turbulent fluid classified in nuclear engineering?

The turbulent fluid does not flow in parallel layers, the lateral mixing is very high, and there is a disruption between the layers. Most industrial flows, especially those in nuclear engineering are turbulent. The flow regime can be also classified according to the geometry of a conduit or flow area.

Why does slow moving liquid create less turbulence?

The slower the liquid moves through a pipe, the more drastic the flow profile. Again, this is not hard to conceptualize: slow moving liquid creates less turbulence, allowing greater disparity between fluid velocity next to the pipe wall compared to the center of the pipe.