Enter the flow velocity, acceleration of gravity, and mean depth into the calculator to determine the Froude number.

Froude Number Calculator

The following equation is used to calculate the Froude number of a gravitational wave.

F = V * Sqrt ( g * h)
  • Where F is the Froude number
  • V is the flow velocity
  • g is the acceleration due to gravity
  • hm is the mean depth

Flow velocity is the speed at which a fluid moves through a particular point or section of a system.

Acceleration due to gravity is the rate at which an object falls towards the Earth’s surface, approximately equal to 9.8 meters per second squared.

Mean depth refers to the average distance from the surface to the bottom of a body of water.

Froude Number Definition

Froude Number is a dimensionless parameter used to determine the relative importance of inertia forces to gravitational forces in a fluid flow.

It is important because it helps understand and predict the behavior of fluid flows, such as waves, river currents, and ship motion.

By comparing Froude Numbers, we can determine if a flow is subcritical (slow and smooth) or supercritical (fast and turbulent), which is crucial in designing efficient and safe hydraulic structures, ship hulls, and water-related systems.

Froude Number Example

How to calculate Froude Number?

  1. First, determine the flow velocity.

    Measure the velocity of flow.

  2. Next, determine the acceleration due to gravity.

    Calculate the acceleration due to gravity.

  3. Next, determine the mean depth.

    Measure the mean depth.

  4. Finally, calculate Froude Number?

    Calculate the Froude Number using the equation above.


Why is the Froude Number important in fluid dynamics?

The Froude Number is crucial in fluid dynamics as it helps predict the behavior of flowing fluids, distinguishing between different flow regimes, such as subcritical and supercritical flows. This understanding is vital for the design and analysis of hydraulic structures, ships, and other water-related systems.

Can the Froude Number be applied to both liquids and gases?

Yes, the Froude Number can be applied to both liquids and gases as it is a dimensionless number that describes the flow characteristics of fluids, irrespective of their phase. It is particularly useful in scenarios where the flow behavior under gravity is of interest.

How does the Froude Number affect ship design?

In ship design, the Froude Number is used to predict the resistance a ship hull will encounter while moving through water. It helps in optimizing the hull shape and size to minimize resistance, ensuring efficient fuel usage and improved speed. A well-designed hull will have a Froude Number that minimizes wave creation and drag.

What is the difference between subcritical and supercritical flow in terms of the Froude Number?

A flow is considered subcritical when the Froude Number is less than 1, indicating that gravitational forces dominate over inertial forces. This results in a slow and smooth flow. Supercritical flow occurs when the Froude Number is greater than 1, meaning inertial forces are greater, leading to a fast and turbulent flow. The Froude Number thus helps in classifying the flow regime and understanding its characteristics.

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