# How to Calculate and Solve for Average Fluid Velocity | Transport Phenomena

**Last Updated on May 14, 2024**

The image above represents average fluid velocity. To calculate the average fluid velocity, two essential parameters are needed and these parameters are **Volume Flow Rate, Q **and **Pipe Diameter (D).**

**The formula for calculating average fluid velocity:**

v’ = ^{4Q} / _{πD²}

Where:

v’ = Average Fluid Velocity

Q = Volume Flow Rate

D = Pipe Diameter

Let’s solve an example;

With a volume flow rate of 42 and a pipe diameter of 8. Find the average fluid velocity?

This implies that;

Q = Volume Flow Rate = 42

D = Pipe Diameter = 8

v’ = ^{4Q} / _{πD²}

v’ = ^{4(42)} / _{π(8)²}

So, v’ = ^{168} / _{π(64)}

v’ = ^{168} / _{201.06}

v’ = 0.835

Therefore, the **average fluid velocity **is **0.835 m/s.**

Read more: How to Calculate and Solve for Reynold’s Number | Transport Phenomena

**Calculating the Volume Flow Rate when the Average Fluid Velocity and the Pipe Diameter are Given**

Q = ^{v’ x πD²} / _{4}

Where:

Q = Volume Flow Rate

v’ = Average Fluid Velocity

D = Pipe Diameter

Let’s solve an example;

Find the volume flow rate when the average fluid velocity is 20 and the pipe diameter is 8.

This implies that;

v’ = Average Fluid Velocity = 20

D = Pipe Diameter = 8

Q = ^{v’ x πD²} / _{4}

Q = ^{20 x π(8)²} / _{4}

That is, Q = ^{20 x 201.06} / _{4}

Q = ^{4021.2} / _{4}

Q = 1005.3

Therefore, the **volume flow rate **is **1005.3.**

Read more: How to Calculate and Solve for Average Velocity | Tube-Bundle Theory | Transport Phenomena

**Calculating the Pipe Diameter when the Average Fluid Velocity and the Volume Flow Rate are Given**

D = √(^{4Q} / _{v’ x π})

Where:

D = Pipe Diameter

v’ = Average Fluid Velocity

Q = Volume Flow Rate

Let’s solve an example;

Find the pipe diameter when the average fluid velocity is 12 and the volume flow rate is 6.

This implies that;

v’ = Average Fluid Velocity = 12

Q = Volume Flow Rate = 6

D = √(^{4Q} / _{v’ x π})

D = √(^{4(6)} / _{12 x π})

So, D = √(^{24} / _{37.69})

D = √(0.637)

D = 0.79

Therefore, the **pipe diameter **is **0.79.**

**How to Calculate the Average Fluid Velocity Using Nickzom Calculator**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the average fluid velocity.

To get the answer and workings of the average fluid velocity using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Materials and Metallurgical **under **Engineering****.**

Now, Click on **Transport Phenomena **under **Materials and Metallurgical**

Now, Click on **Average Fluid Velocity **under **Transport Phenomena
**

The screenshot below displays the page or activity to enter your values, to get the answer for the average fluid velocity according to the respective parameter which is the **Volume Flow Rate, Q **and **Pipe Diameter (D).**

Now, enter the values appropriately and accordingly for the parameters as required by the **Volume Flow Rate, Q** is **42 **and **Pipe Diameter (D)** is **8**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the average fluid velocity and presents the formula, workings and steps too.