"In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity."
Refers to fluid flow that is characterized by chaotic and unpredictable changes in velocity and pressure.
Fluid Properties: This includes the properties of fluids, such as density, viscosity, and compressibility, which are relevant to understanding turbulent flow.
Reynolds Number: Reynolds number is a dimensionless quantity that characterizes the type of fluid flow, specifically laminar or turbulent. It can help predict the onset of turbulence.
Navier-Stokes Equations: These equations describe fluid flow, including turbulent flow. They include conservation of mass, momentum, and energy equations.
Boundary Layers: Boundary layers are thin layers of fluid near a surface that characterizes the behavior of turbulent flow. Understanding boundary layers is critical in predicting fluid flow dynamics.
Turbulence Models: Turbulence models are mathematical models that simulate turbulent flow. These models are critical in industries where turbulent flow is prevalent, such as in aviation and automotive manufacturing.
Eddy Viscosity: Eddy viscosity is a measure of the turbulence in a fluid. It is the exchange of momentum in a turbulent flow system, and it is typically used in turbulence models.
Mixing and Dispersion: Turbulent flow can result in efficient mixing and dispersion of fluids, which is useful in many manufacturing processes, environmental cleanup, and chemical reactions.
Reynolds Stress: Reynolds stress is the correlation between the fluctuating velocity components in turbulent flow. It is important in the modeling of turbulent flow.
Turbulent Boundary Layers: Turbulent boundary layers occur in high-speed fluid flow, typically near walls, and they have significant effects on the fluid flow behavior.
Wall Shear Stress: Wall shear stress is the force exerted by a fluid on a surface, such as a wall. It is essential in predicting the behavior of turbulent flows.
Wake Formation: Wake formation occurs when fluid flows past a solid object. The flow behind the object is turbulent, and the wake can be characterized using models of turbulent flow.
Heat Transfer in Turbulent Flow: Turbulent flow can transfer heat much more efficiently than laminar flow, which has implications for energy production, climate modeling, and other industries.
Drag Reduction: Turbulent flow causes higher drag on objects moving through fluids. Understanding and reducing drag has significant implications in industries such as transportation.
Vortex Dynamics: Vortex dynamics can occur in turbulent flow and have implications in many areas, including weather prediction, oceanic currents, and wind turbine design.
Turbulent Flow Control: Controlling turbulent flow can be beneficial in various industries, including automobile manufacturing, reduction of drag on ships, and atmospheric reentry vehicles.
Transitional turbulence: This occurs when the flow is in the process of transitioning from laminar to turbulent. The turbulence appears in localized regions and is not continuous.
Steady turbulence: This is a type of turbulence that is continuous and happens in a steady-state flow. The fluid appears to move erratically, with mixing and turbulent eddies distributed throughout the flow.
Intermittent turbulence: This type of turbulent flow is characterized by bursts of turbulent activity, followed by periods of laminar flow. This can occur in situations where the fluid is flowing over an uneven surface or through a confined space.
Shear turbulence: This type of turbulence is caused by the interaction between fluid layers with different velocities. The shear force creates small-scale turbulence that can affect the larger scale flow of the fluid.
Free turbulence: This is the most common type of turbulence, which occurs when a fluid is flowing freely without any solid objects nearby that could cause disturbances.
Wall turbulence: This type of turbulence is experienced when a fluid is flowing past a solid surface or a boundary. It is characterized by the formation of eddies and swirls close to the wall, and the intensity of turbulence decreases further away from the wall.
Homogeneous turbulence: This type of turbulence occurs when the flow properties are the same throughout the flow domain. This occurs in situations where the flow is isotropic and the velocity distribution is uniform.
Isotropic turbulence: This is a type of homogeneous turbulence in which the velocity distribution is the same in all directions.
Axisymmetric turbulence: This type of turbulence occurs in situations where the flow has an axis of symmetry. Examples include flow through pipes or channels, where the axis of symmetry is the centerline of the pipe or channel.
Coherent turbulence: This type of turbulence is characterized by the formation of coherent structures, such as vortex tubes or eddies. These structures are maintained by the fluid dynamics of the flow, and they can influence the overall behavior of the fluid.
"It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers."
"Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney."
"Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity."
"For this reason, turbulence is commonly realized in low viscosity fluids."
"In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other."
"Drag due to friction effects increases. This increases the energy needed to pump fluid through a pipe."
"The onset of turbulence can be predicted by the dimensionless Reynolds number, the ratio of kinetic energy to viscous damping in a fluid flow."
"Richard Feynman described turbulence as the most important unsolved problem in classical physics."
"The turbulence intensity affects many fields, for examples fish ecology, air pollution, precipitation, and climate change."