Centrifugal pump

How does a centrifugal pump work?

Centrifugal pumps have a wide range of applications where the pressure increase is caused by centrifugal forces. In this article you will learn more about how a centrifugal pump...
Elevation head (geodetic suction head and discharge head)

Pressure head and head loss

Learn more about the difference between elevation head, pressure head, friction head (head loss) and total static head of a piping system in this article.
Moody chart for determining the Darcy friction factor as a function of the Reynolds number

Moody chart (diagram)

The Moody diagram is a chart showing the Darcy friction factor of a pipe as a function of the Reynolds number for selected roughnesses of the pipe wall. Learn...
Valve and pipe elbow in a pipeline system

Pressure loss in pipe systems (Darcy friction factor)

Pressure losses in pipes are caused by internal friction of the fluid (viscosity) and friction between fluid and wall. Pressure losses also occur in components. Learn more about it...
Flettner rotors on a ship

Magnus effect

The Magnus effect refers to the lateral force acting on rotating round bodies in a flow! Learn more about it in this article.
Filling of a higher located pool

Exercises with solutions based on the Bernoulli equation

In this article exercises with solutions based on the Bernoulli equation are given. Bernoulli equation The Bernoulli equation is...
Venturi tube (Venturi nozzle)

Venturi effect

The Venturi effect describes the decrease of (static) pressure in flowing fluids with increasing flow velocity due to a constricted section. Learn more about it in this article.
Prandtl tube (dynamic pressure probe)

How does a Prandtl tube work?

A Prandtl tube is used to measure the dynamic pressure. From this, the flow speed relative to the tube can be determined. Erfahren Sie in diesem Artikel mehr darüber....
Blowing off a roof on the lee side by a storm

Examples and applications of the Venturi effect

Learn more about examples and technical applications of the Venturi effect in this article. This article provides answers to the following questions,...
Widerstandsbeiwerte verschiedener Körper

Drag coefficient (friction and pressure drag)

Drag coefficients are dimensionless similarity parameters for describing the drag of flowed around bodies. Learn more about them in this article. This...
Completely laminar flow around a sphere

Flow around spherical bodies (Stokes’ law of friction)

Stokes' law of friction describes the drag force acting on a spherical body around which a laminar flow passes. Learn more about it in this article.
Turbulators (vertex generators) on the wing of an airplane to generate a turbulent flow around it

Flow separation (boundary layer separation)

In the case of a boundary layer separation (flow separation), the flow can no longer follow the profile of the body around which it flows and separates turbulently from...
Hydrodynamische Grenzschicht, thermische Grenzschicht und Konzentrationsgrenzschicht

Dimensionless numbers of the boundary layers (Prandtl, Schmidt and Lewis number)

To describe the heat and mass transport, dimensionless numbers are introduced to describe the processes within the boundary layers. Learn more about this in this article.
Definition of the thermal boundary layer (temperature boundary layer)

Thermal and concentration boundary layer

In addition to the hydrodynamic boundary layer, the thermal boundary layer and the concentration boundary layer also have a decisive influence on the entire heat and mass transport in...
Acceleration of the air when flowing around a wing and the resulting decrease in pressure

Parasitic drag (skin friction drag & form/pressure drag)

Drag is the force of resistance that a moving body experiences in a fluid due to frictional and pressure forces. Learn more about it in this article.
Convective heat transfer between a heated pipe and a fluid flowing through it

Prandtl number

The Prandtl number is a dimensionless similarity parameter to describe the transport of heat and momentum. Learn more about it in this article.
Lewis number as a measure for the ratio of the thickness of the thermal boundary layer and the concentration boundary layer

Lewis number

The Lewis number is a dimensionless similarity parameter to describe heat and mass transport. Learn more about it in this article. This...
Schmidt number as a measure for the ratio of the thickness of the hydrodynamic boundary layer and the concentration boundary layer

Schmidt number

The Schmidt-number is a dimensionless similarity parameter to describe transport of mass and momentum. Learn more about this topic in this article.
Convective heat transfer at a flat plate with laminar-turbulent flow

Calculation of the Nusselt numbers for forced flows over plates and in pipes

In this article you will find formulas for calculating the local and average Nusselt numbers for forced flows over plates and in pipes with circular cross sections.
Definition of the heat transfer coefficient for convective heat transport

Heat transfer coefficient for thermal convection

The heat transfer coefficient describes the convective heat transfer from a solid to a flowing fluid and vice versa! Learn more about it in this article.
Velocity gradients in a laminar and turbulent boundary layer

Hydrodynamic boundary layer

The hydrodynamic boundary layer of a flow has a decisive influence on heat and mass transport. Learn more about it in this article.
Influence of the hydrodynamic and thermal boundary layer on convective heat transfer

Nusselt number to describe convective heat transfer

The Nusselt number is a dimensionless similarity parameter to describe convective heat transfer, independent of the size of the system. Learn more about it in this article.
Pathline (trajectory) of a paper ship in a steady stream

Streamlines, pathlines, streaklines and timelines

In order to make the flow of fluids "visible", one often uses the model of streamlines, pathlines (trajectories), streaklines or timelines. Learn more about the difference between these lines...
Fluid element on a curved streamline

Equation of motion of a fluid on a streamline

In this article we want to derive the equation of motion of a fluid element on a streamline. For this purpose we describe the equation of motion in the...
Derivation of the Bernoulli equation using a flow in a pipe

Derivation of the Bernoulli equation

The Bernoulli equation describes the relationship between static, dynamic and hydrostatic pressure for inviscid and incompressible fluids. Learn more about it in this article.
Pressure difference as drive for flows

Derivation of Hagen-Poiseuille equation for pipe flows with friction

The Hagen-Poiseuille equation describes the parabolic velocity profile of frictional, laminar pipe flows of incompressible, Newtonian fluids. Learn more about it in this article.
Setup of a rotational viscometer

Experimental determination of viscosity (viscometer)

Viscometry is the experimental determination of the viscosity of liquids and gases with so-called viscometers. Learn more about it in this article.
Division of the pressure drop to different causes

Energetic analysis of the Hagen-Poiseuille law

The Hagen-Poiseuille equation for describing the parabolic velocity profile of fluids in pipes applies only to long pipes for energy reasons! Learn more about it in this article.
Aircraft model in a wind tunnel to study the flow around the aircraft

Reynolds number (laminar and turbulent flow)

The Reynolds number is a dimensionless similarity parameter for describing a forced flow, e.g. whether it is an alminar or turbulent flow. Learn more about it in this article.
Toothpaste as a typical example of a non-Newtonian fluid (Bingham Fluid)

Viscosity of liquids and gases

The viscosity of a fluid is a measure of the internal resistance to flow! It is caused by intermolecular forces and transport of momentum within the fluid. Learn more...
Dry adiabatic and wet adiabatic lapse rate (temperature gradient)

Barometric formula for an adiabatic atmosphere

The barometric formula for an adiabatic atmosphere takes into account the decrease in temperature with increasing altitude and the associated effects on air pressure. More information about this and...
Calculation of the outflow speed of a liquid through an orifice (Torricelli's law theorem)

Discharge of liquids (Torricelli’s law)

Torricelli's law (Torricelli's theorem) states that the discharge velocity of a liquid equals a free fall of the liquid from the liquid surface to the opening of the tank.
Hot air balloon

How does a hot air balloon work: Buoyancy in gases

Buoyant forces act not only in liquids but also in gases. This will be illustrated in the following by the example of a hot air balloon.
Hydraulic bottle jack

How does a hydraulic jack work: Pascals law

A hydraulic jack is based on Pascal's law, which states that the pressure in liquids acts equally in all directions. This article...
Demonstration of the siphon-spillway-principle

Siphon

This article provides answers to the following questions, among others: How does a siphon work?What is the maximum height to the apex of the flexible tube...
Influence of vessel shape on hydrostatic pressure

Pressure in liquids (hydrostatic pressure)

This article provides answers to the following questions, among others: What causes the hydrostatic pressure in liquids?On which variables does the hydrostatic pressure depend?What is the...
Container ship

How do boats float: Buoyancy in liquids

Buoyancy is the force directed against gravity that an object experiences when submerged in a fluid (liquid or gas). More information on how buoyancy is formed can be found...
Water tower

Applications and examples of hydrostatic pressure

This article provides answers to the following questions, among others: Which properties of the hydrostatic pressure could Pascal demonstrate with his barrel experiment?How does the pressure...
Drinking straw in a glass with water

How does a drinking straw work?

This article provides answers to the following questions, among others: How does drinking with a straw work from a physical point of view?What role does ambient...
Stratification of the earth's atmosphere

Barometric formula for an isothermal atmosphere

The barometric formula describes the decrease of air pressure with increasing altitude. Without the influence of the temperature changes, the air pressure decreases by about 1.2% per 100 meters...
Pressure on a flat surface

Pressure in gases

This article provides answers to the following questions, among others: What causes the pressure in gases?How is the unit bar converted into the unit Pascal?What is...
Pressing a drawing pin together between two fingers

Pressure

This article provides answers to the following questions, among others: What is pressure?In what way does the contact pressure differ from a gas pressure or liquid...