Boundary layer, the Glossary

Table of Contents

1. 92 relations: A priori and a posteriori, Adhesion, Adverse pressure gradient, Aerodynamics, Airbus, Aircraft, Airfoil, Atmosphere of Earth, Aurora D8, Azimuth, Bernoulli's principle, Blasius boundary layer, Boundary layer control, Boundary layer suction, Boundary layer thickness, Boundary microphone, Bypass ratio, Cartesian coordinate system, Closed-form expression, Coriolis force, Diurnal air temperature variation, Drag (physics), Ekman layer, Falkner–Skan boundary layer, Flow separation, Fluid, Fluid mechanics, Force, Free streaming, Fuel economy in aircraft, Fuselage, Gamma function, Glider (aircraft), Gradient, Heat transfer, Heidelberg, Hendrik Tennekes, Hermann Schlichting, Incompressible flow, International Congress of Mathematicians, International Council of the Aeronautical Sciences, John L. Lumley, Keith Stewartson, Laminar flow, Laminar–turbulent transition, Law of the wall, Ludwig Prandtl, Mean, Momentum, Navier–Stokes equations, ... Expand index (42 more) »

2. Boundary layers

A priori and a posteriori

A priori ('from the earlier') and a posteriori ('from the later') are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on experience.

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Adhesion

Adhesion is the tendency of dissimilar particles or surfaces to cling to one another.

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Adverse pressure gradient

In fluid dynamics, an adverse pressure gradient is a pressure gradient in which the static pressure increases in the direction of the flow.

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Aerodynamics

Aerodynamics (ἀήρ aero (air) + δυναμική (dynamics)) is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing.

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Airbus

Airbus SE is a European multinational aerospace corporation.

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Aircraft

An aircraft (aircraft) is a vehicle that is able to fly by gaining support from the air.

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Airfoil

An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more lift than drag. Boundary layer and airfoil are aircraft wing design.

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Atmosphere of Earth

The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.

See Boundary layer and Atmosphere of Earth

Aurora D8

The Aurora D8, also known as the D8 Airliner, is an airliner concept under development as of mid 2017.

See Boundary layer and Aurora D8

Azimuth

An azimuth (from the directions) is the horizontal angle from a cardinal direction, most commonly north, in a local or observer-centric spherical coordinate system.

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Bernoulli's principle

Bernoulli's principle is a key concept in fluid dynamics that relates pressure, speed and height.

See Boundary layer and Bernoulli's principle

Blasius boundary layer

In physics and fluid mechanics, a Blasius boundary layer (named after Paul Richard Heinrich Blasius) describes the steady two-dimensional laminar boundary layer that forms on a semi-infinite plate which is held parallel to a constant unidirectional flow. Boundary layer and Blasius boundary layer are boundary layers.

See Boundary layer and Blasius boundary layer

Boundary layer control

Boundary layer control refers to methods of controlling the behaviour of fluid flow boundary layers. Boundary layer and boundary layer control are aircraft wing design and boundary layers.

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Boundary layer suction

Boundary layer suction is a boundary layer control technique in which an air pump is used to extract the boundary layer at the wing or the inlet of an aircraft. Boundary layer and boundary layer suction are aircraft wing design and boundary layers.

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Boundary layer thickness

This page describes some of the parameters used to characterize the thickness and shape of boundary layers formed by fluid flowing along a solid surface. Boundary layer and boundary layer thickness are boundary layers.

See Boundary layer and Boundary layer thickness

Boundary microphone

A boundary microphone (or pressure zone microphone) is one or more small omnidirectional or cardioid condenser mic capsule(s) positioned near or flush with a boundary (surface) such as a floor, table, or wall.

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Bypass ratio

The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core.

See Boundary layer and Bypass ratio

Cartesian coordinate system

In geometry, a Cartesian coordinate system in a plane is a coordinate system that specifies each point uniquely by a pair of real numbers called coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, called coordinate lines, coordinate axes or just axes (plural of axis) of the system.

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Closed-form expression

In mathematics, an expression is in closed form if it is formed with constants, variables and a finite set of basic functions connected by arithmetic operations (and integer powers) and function composition.

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Coriolis force

In physics, the Coriolis force is an inertial (or fictitious) force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame.

See Boundary layer and Coriolis force

Diurnal air temperature variation

In meteorology, diurnal temperature variation is the variation between a high air temperature and a low temperature that occurs during the same day.

See Boundary layer and Diurnal air temperature variation

Drag (physics)

In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the relative motion of any object, moving with respect to a surrounding fluid.

See Boundary layer and Drag (physics)

Ekman layer

The Ekman layer is the layer in a fluid where there is a force balance between pressure gradient force, Coriolis force and turbulent drag.

See Boundary layer and Ekman layer

Falkner–Skan boundary layer

In fluid dynamics, the Falkner–Skan boundary layer (named after V. M. Falkner and Sylvia W. Skan) describes the steady two-dimensional laminar boundary layer that forms on a wedge, i.e. flows in which the plate is not parallel to the flow. Boundary layer and Falkner–Skan boundary layer are boundary layers.

See Boundary layer and Falkner–Skan boundary layer

Flow separation

In fluid dynamics, flow separation or boundary layer separation is the detachment of a boundary layer from a surface into a wake. Boundary layer and flow separation are boundary layers.

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Fluid

In physics, a fluid is a liquid, gas, or other material that may continuously move and deform (flow) under an applied shear stress, or external force.

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Fluid mechanics

Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them.

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Force

A force is an influence that can cause an object to change its velocity, i.e., to accelerate, meaning a change in speed or direction, unless counterbalanced by other forces.

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Free streaming

In astronomy, a free streaming particle, often a photon, is one that propagates through a medium without scattering.

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Fuel economy in aircraft

The fuel economy in aircraft is the measure of the transport energy efficiency of aircraft.

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Fuselage

The fuselage (from the French fuselé "spindle-shaped") is an aircraft's main body section.

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Gamma function

In mathematics, the gamma function (represented by, the capital letter gamma from the Greek alphabet) is one commonly used extension of the factorial function to complex numbers.

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Glider (aircraft)

A glider is a fixed-wing aircraft that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose free flight does not depend on an engine.

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Gradient

In vector calculus, the gradient of a scalar-valued differentiable function f of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p gives the direction and the rate of fastest increase.

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Heat transfer

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems.

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Heidelberg

Heidelberg (Heidlberg) is a city in the German state of Baden-Württemberg, situated on the river Neckar in south-west Germany.

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Hendrik Tennekes

Hendrik (Henk) Tennekes (born December 13, 1936, Kampen died July 3, 2021, Arnhem) was the director of research at the Royal Dutch Meteorological Institute (Koninklijk Nederlands Meteorologisch Instituut, or KNMI), and was a Professor of Aeronautical Engineering at Pennsylvania State University and Professor of Meteorology at the Vrije Universiteit Amsterdam (Free University (VU) in Amsterdam).

See Boundary layer and Hendrik Tennekes

Hermann Schlichting

Hermann Schlichting (22 September 1907 – 15 June 1982) was a German fluid dynamics engineer.

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Incompressible flow

In fluid mechanics, or more generally continuum mechanics, incompressible flow (isochoric flow) refers to a flow in which the material density of each fluid parcel — an infinitesimal volume that moves with the flow velocity — is time-invariant.

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International Congress of Mathematicians

The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics.

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International Council of the Aeronautical Sciences

The International Council of the Aeronautical Sciences (ICAS) is a worldwide institution, established as an international forum for individual national aeronautical professional associations.

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John L. Lumley

John Leask Lumley (4 November 1930 in Detroit, Michigan – 30 May 2015 in Ithaca, New York) was an American fluid dynamicist and a professor at Cornell University.

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Keith Stewartson

Keith Stewartson (20 September 1925 – 7 May 1983) was an English mathematician and fellow of the Royal Society.

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Laminar flow

Laminar flow is the property of fluid particles in fluid dynamics to follow smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing.

See Boundary layer and Laminar flow

Laminar–turbulent transition

In fluid dynamics, the process of a laminar flow becoming turbulent is known as laminar–turbulent transition. Boundary layer and laminar–turbulent transition are boundary layers.

See Boundary layer and Laminar–turbulent transition

Law of the wall

In fluid dynamics, the law of the wall (also known as the logarithmic law of the wall) states that the average velocity of a turbulent flow at a certain point is proportional to the logarithm of the distance from that point to the "wall", or the boundary of the fluid region.

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Ludwig Prandtl

Ludwig Prandtl (4 February 1875 – 15 August 1953) was a German fluid dynamicist, physicist and aerospace scientist.

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Mean

A mean is a numeric quantity representing the center of a collection of numbers and is intermediate to the extreme values of a set of numbers.

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Momentum

In Newtonian mechanics, momentum (momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object.

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Navier–Stokes equations

The Navier–Stokes equations are partial differential equations which describe the motion of viscous fluid substances.

See Boundary layer and Navier–Stokes equations

Nikola Tesla

Nikola Tesla (. Random House Webster's Unabridged Dictionary.,; 1856 – 7 January 1943) was a Serbian-American engineer, futurist, and inventor.

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No-slip condition

In fluid dynamics, the no-slip condition is a boundary condition which enforces that at a solid boundary, a viscous fluid attains zero bulk velocity.

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ONERA

The Office national d'études et de recherches aérospatiales (ONERA) is the French national aerospace research centre.

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Parasitic drag

Parasitic drag, also known as profile drag, is a type of aerodynamic drag that acts on any object when the object is moving through a fluid.

See Boundary layer and Parasitic drag

Partial differential equation

In mathematics, a partial differential equation (PDE) is an equation which computes a function between various partial derivatives of a multivariable function.

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Paul A. Libby

Paul Andrews Libby (September 4, 1921 – November 2, 2021) was a professor of mechanical and aerospace engineering at the University of California, San Diego, a specialist in the field of combustion and aerospace engineering.

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Paul Richard Heinrich Blasius

Paul Richard Heinrich Blasius (9 August 1883 – 24 April 1970) was a German fluid dynamics physicist.

See Boundary layer and Paul Richard Heinrich Blasius

Peniche (fluid dynamics)

A peniche (or stand-off) is material inserted between a half-model, often of an airplane, and the wall of a wind tunnel.

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Perturbation theory

In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem.

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Physics

Physics is the natural science of matter, involving the study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.

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Planetary boundary layer

In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface.

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Porosity

Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%.

See Boundary layer and Porosity

Prandtl number

The Prandtl number (Pr) or Prandtl group is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum diffusivity to thermal diffusivity.

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Pressure

Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

See Boundary layer and Pressure

Propfan

A propfan, also called an open rotor engine, open fan engine or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both.

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Propulsive efficiency

In aerospace engineering, concerning aircraft, rocket and spacecraft design, overall propulsion system efficiency \eta is the efficiency with which the energy contained in a vehicle's fuel is converted into kinetic energy of the vehicle, to accelerate it, or to replace losses due to aerodynamic drag or gravity.

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Propulsor

A propulsor is a mechanical device that gives propulsion.

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Qian Xuesen

Qian Xuesen (11 December 191131 October 2009; also spelled as Hsue-shen Tsien) was a Chinese aerospace engineer and cyberneticist who made significant contributions to the field of aerodynamics and established engineering cybernetics.

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Reynolds decomposition

In fluid dynamics and turbulence theory, Reynolds decomposition is a mathematical technique used to separate the expectation value of a quantity from its fluctuations.

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Reynolds number

In fluid dynamics, the Reynolds number is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces.

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Richard von Mises

Richard Martin Edler von Mises (19 April 1883 – 14 July 1953) was an Austrian scientist and mathematician who worked on solid mechanics, fluid mechanics, aerodynamics, aeronautics, statistics and probability theory.

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Scale analysis (mathematics)

Scale analysis (or order-of-magnitude analysis) is a powerful tool used in the mathematical sciences for the simplification of equations with many terms.

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Self-similarity

In mathematics, a self-similar object is exactly or approximately similar to a part of itself (i.e., the whole has the same shape as one or more of the parts).

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Shear stress

Shear stress (often denoted by, Greek: tau) is the component of stress coplanar with a material cross section.

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Similitude

Similitude is a concept applicable to the testing of engineering models.

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Simple shear

Simple shear is a deformation in which parallel planes in a material remain parallel and maintain a constant distance, while translating relative to each other.

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Skin friction drag

Skin friction drag is a type of aerodynamic or hydrodynamic drag, which is resistant force exerted on an object moving in a fluid.

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Stokes problem

In fluid dynamics, Stokes problem also known as Stokes second problem or sometimes referred to as Stokes boundary layer or Oscillating boundary layer is a problem of determining the flow created by an oscillating solid surface, named after Sir George Stokes.

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Stream function

In fluid dynamics, two types of stream function are defined.

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Surface layer

The surface layer is the layer of a turbulent fluid most affected by interaction with a solid surface or the surface separating a gas and a liquid where the characteristics of the turbulence depend on distance from the interface.

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Tesla turbine

Tesla turbine at Nikola Tesla Museum The Tesla turbine is a bladeless centripetal flow turbine invented by Nikola Tesla in 1913. Boundary layer and Tesla turbine are boundary layers.

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Theodore von Kármán

Theodore von Kármán (szőllőskislaki) Kármán Tódor, May 11, 1881May 6, 1963), was a Hungarian-American mathematician, aerospace engineer, and physicist who worked in aeronautics and astronautics.

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Thermal boundary layer thickness and shape

This page describes some parameters used to characterize the properties of the thermal boundary layer formed by a heated (or cooled) fluid moving along a heated (or cooled) wall. Boundary layer and thermal boundary layer thickness and shape are boundary layers.

See Boundary layer and Thermal boundary layer thickness and shape

Thermodynamic system

A thermodynamic system is a body of matter and/or radiation separate from its surroundings that can be studied using the laws of thermodynamics.

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Turbine

A turbine (from the Greek τύρβη, tyrbē, or Latin turbo, meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work.

See Boundary layer and Turbine

Turbulator

A turbulator is a device that turns a laminar boundary layer into a turbulent boundary layer. Boundary layer and turbulator are aircraft wing design.

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Turbulence

In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity.

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Turbulence modeling

In fluid dynamics, turbulence modeling is the construction and use of a mathematical model to predict the effects of turbulence.

See Boundary layer and Turbulence modeling

Viscosity

The viscosity of a fluid is a measure of its resistance to deformation at a given rate.

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Vortex generator

A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (or airfoil, such as an aircraft wing) or a rotor blade of a wind turbine. Boundary layer and vortex generator are aircraft wing design.

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Wake (physics)

In fluid dynamics, a wake may either be.

See Boundary layer and Wake (physics)

Wing

A wing is a type of fin that produces lift while moving through air or some other fluid.

See Boundary layer and Wing

See also

Boundary layers

• Blasius boundary layer
• Blown flap
• Boundary layer
• Boundary layer control
• Boundary layer suction
• Boundary layer thickness
• Bypass transition
• Coandă effect
• Falkner–Skan boundary layer
• Flow separation
• Görtler vortices
• Laminar–turbulent transition
• Mangler Transformation
• Sweeping jet actuators
• Tesla turbine
• Thermal boundary layer thickness and shape
• Transition point

References

[1] https://en.wikipedia.org/wiki/Boundary_layer

Also known as Boundary layer effect, Boundary layer flow, Boundary layer theory, Boundary layers, Boundary-layer, Boundary-layer effect, Convective Boundary Layer, Fluid boundary layer, Shear layers, Surface boundary layer, Turbulent boundary layer.

, Nikola Tesla, No-slip condition, ONERA, Parasitic drag, Partial differential equation, Paul A. Libby, Paul Richard Heinrich Blasius, Peniche (fluid dynamics), Perturbation theory, Physics, Planetary boundary layer, Porosity, Prandtl number, Pressure, Propfan, Propulsive efficiency, Propulsor, Qian Xuesen, Reynolds decomposition, Reynolds number, Richard von Mises, Scale analysis (mathematics), Self-similarity, Shear stress, Similitude, Simple shear, Skin friction drag, Stokes problem, Stream function, Surface layer, Tesla turbine, Theodore von Kármán, Thermal boundary layer thickness and shape, Thermodynamic system, Turbine, Turbulator, Turbulence, Turbulence modeling, Viscosity, Vortex generator, Wake (physics), Wing.