Flow Velocity Calculator

About the Flow Velocity Calculator

Calculates the fluid velocity in a pipe from the volumetric flow rate and the pipe's internal diameter.

How to use this calculator

1. Enter the flow rate, usually in \(m^3/s\) or another volume per time unit.
2. Enter the cross-sectional area of the pipe or channel, usually in \(m^2\).
3. Use the calculator to find the velocity in \(m/s\).
4. Check that your units are consistent before comparing results.

The formula explained

The formula \(v = \frac{Q}{A}\) computes flow velocity from flow rate and area. It shows that velocity increases when flow rate goes up and decreases when area gets larger.

• v = flow velocity, the speed of the fluid
• Q = flow rate, the volume of fluid moving per unit time
• A = cross-sectional area of the pipe or channel

Step by step method

1. Write down the flow rate \(Q\) and the area \(A\).
2. Divide \(Q\) by \(A\) using \(v = \frac{Q}{A}\).
3. Simplify the result and include the correct units, usually \(m/s\).

Worked example

Problem. A pipe carries water at a flow rate of \(0.8\\,m^3/s\) through a cross-sectional area of \(0.2\\,m^2\). Find the flow velocity.

1. Use the formula \(v = \frac{Q}{A}\).
2. Substitute the values: \(v = \frac{0.8}{0.2}\).
3. Compute \(v = 4\\,m/s\).

Tips and common mistakes

• Make sure the area is the cross-sectional area, not the surface area of the pipe.
• If your units are not in \(m^3/s\) and \(m^2\), convert them first so the velocity comes out correctly.

Frequently asked questions