Bernoulli Principle
Bernoulli Principle - Related Videos
01:01
Bernoulli's Principle
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2023
Bernoulli's equation incorporates how fluid pressure changes across a static, incompressible fluid by equating the kinetic energy contribution to zero. It is also helpful in analyzing horizontal flows in which the gravitational energy density is constant throughout. The latter equation is so useful that it is called Bernoulli's principle. According to Bernoulli's principle, the fluid pressure drops if the speed increases and vice versa. Bernoulli's principle has several applications. It is used...
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Bernoulli's Principle: Applications
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2023
There are many devices and situations in which fluid flows at a constant height and so can be analyzed using Bernoulli's principle. These devices include, but are not limited to, entrainment devices and fluid flow measuring devices. Entrainment devices use a high fluid speed to create low pressures and, thus, entrain one fluid into another. Some examples of these devices are given below: A Bunsen burner uses an adjustable gas nozzle to entrain air for proper combustion. An atomizer uses a...
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Bernoulli's Equation
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2023
In the middle of the nineteenth century, it was observed that two trains passing each other at a high relative speed get pulled towards each other. The same occurs when two cars pass each other at a high relative speed. The reason is that the fluid pressure drops in the region where the fluid speeds up. As the air between the trains or the cars increases in speed, its pressure reduces. The pressure on the outer parts of the vehicles is still the atmospheric pressure, while the resultant...
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Bernoulli's Equation: Problem Solving
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2026
A Venturi meter is essential for measuring fluid flow rates in pipelines. It utilizes the relationship between fluid velocity and pressure described by Bernoulli's equation. When installed in a sewage system, the Venturi meter accurately determines the wastewater flow rate by measuring pressure differences. The first step is to compute the cross-sectional areas of the pipe and the Venturi throat to analyze the pressure difference indicated by the pressure gauge. Next, the continuity equation is...
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Bernoulli's Equation for Flow Along a Streamline
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2025
Bernoulli's equation relates the energy conservation in a fluid moving along a streamline. The equation applies to incompressible and inviscid fluids under steady flow. For such a flow, Newton's second law is applied to a small fluid element, which experiences forces due to pressure differences, gravity, and velocity variations. The force balance leads to the following form of Bernoulli's equation: Here, P is the pressure, ρ is the density of the fluid, v is velocity, g denotes the...
FAQs
Elevation represents a gravitational contribution to the fluid’s mechanical energy. When a streamline rises, part of the available energy is associated with elevation, so pressure and velocity changes cannot be interpreted from speed alone. Engineering analyses therefore compare pressure, flow speed, and height together rather than assuming that every pressure decrease results only from acceleration.
The ideal relationship assumes steady flow of an incompressible fluid without substantial energy loss. Viscosity and turbulence can dissipate mechanical energy, while compressibility can alter how fluid density responds during motion. Under those conditions, the ideal pressure-speed relationship may not predict the actual result unless the analysis accounts for the factors that make the flow nonideal.
The relationship is applied along a streamline, which provides the path for comparing fluid conditions during motion. Engineers evaluate pressure, velocity, and elevation at selected locations on that path. This restriction helps define where the comparison is valid and prevents unrelated flow regions from being treated as though they share the same energy relationship.
An engineer compares two locations in the pipe and considers their fluid speeds and elevations. If the height remains effectively unchanged, the speed difference provides the basis for estimating the corresponding pressure change. The result is most useful for idealized analysis, while viscosity, turbulence, or other energy losses require caution when interpreting the estimate.
A Venturi meter uses changes in flow geometry to create conditions that can be analyzed through pressure and velocity relationships. Engineers use the expected change between sections when sizing the device for flow measurement. The principle connects the pressure behavior produced by the meter’s geometry with the fluid-motion quantities needed for engineering analysis.
For airfoils, the principle helps explain lift by relating differences in fluid motion to pressure behavior around the surface. In nozzles, it supports analysis of how flow conditions change through the device. Pumps also require energy analysis, but real systems must be evaluated carefully when losses or nonideal flow influence the outcome.