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Bernoulli equation

    The Bernoulli equation and Venturi tube are concepts in engineering and physics related to hydraulics (fluid mechanics). Let us explain each of them:

    Bernoulli’s equation is an important equation in hydraulics (fluid mechanics) and is used to understand the behavior of fluids as they flow. The equation is based on conservation of energy and describes the relationship between pressure, velocity and height in a fluid.

    1. Bernoulli’s equation:


    The equation shows that the sum of pressure, kinetic energy, and facial energy (which is related to gravity) in a fluid remains constant across different points in the fluid flow. This allows us to understand how fluid flow is affected by pressure, velocity, and height.

    Examples of Bernoulli’s equation:

    1. A plane flying in the air:

    When an airplane is in the air, Bernoulli’s equation is used to understand how pressure and speed on the wings are affected. The pressure on the upper side of the wing is lower than on the lower side, creating the lift that keeps the plane in the air.

    2. Water valve:

    When you open a water valve in a high tank, water falls downward quickly. Bernoulli’s equation can be used to calculate the water velocity at the valve outlet using the height and pressure in the tank.

    3. A car driving fast:

    When a car is traveling at high speed, Bernoulli’s equation can be used to understand how speed affects the pressure on the front end of the car. This helps in better designing cars to reduce air resistance and increase fuel efficiency.

    2. Venturi tube:

    A Venturi tube is a device used to measure the speed of fluid flow. A venturi tube consists of a tapered inlet that gradually widens until it reaches an outlet area, or small opening. When fluid flows from the inlet to the outlet, its velocity changes in inverse proportion to the cross-sectional area of the pipe.

    Venturi tube helps in measuring the fluid flow velocity by measuring the pressure at the narrow point and using the Venturi equation. The equation takes the following form:


    How a Venturi tube works:

    As the fluid enters the tapered inlet of the venturi tube, the fluid undergoes a gradual constriction in the tube, increasing its velocity. When the fluid reaches the narrow outlet region, its pressure increases dramatically and its velocity decreases. The Venturi equation helps calculate the velocity of the fluid upon exiting the outlet region using height and cross-sectional area.

    Venturi tube applications:

    1. Water flow measurement:

    One of the most important applications of a venturi tube is to measure water flow in water distribution networks. When water passes through a venturi tube, its velocity can be measured and thus the volume of water passing can be calculated.

    2. Gas flow measurement:

    Venturi tube can also be used to measure the flow of gases such as air and natural gas. This is useful in industries such as the gas and air conditioning industry.

    3. Its use in scientific research:

    Venturi tube is used in scientific research and experiments to measure the flow velocities of liquids and gases. This allows researchers to understand the behavior of liquids and gases under various conditions.


    Bernoulli’s equation and Venturi tube are important concepts in fluid dynamics. They help us understand how liquids and gases interact and how to measure their speed and flow. Their applications range from measuring water flow in our daily lives to their use in scientific research and multiple industries.

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    Khaled Saleh

    Khaled Saleh