How to create an inlet velocity profile in Fluent

Usually, users use a uniform inlet velocity boundary condition for their simulations. However, sometimes the simulations will benefit more when a developed profile is used, since that represents a more realistic flow feature. In this blog you will le

For this example, we will create this turbulent profile (n = 7): 

1 In Fluent, create the following expressions:
a) coordinate r

Use the coordinates on the plane where the inlet is defined, in this case, Y and Z. 

b) Maximum Velocity (umax)

This could be a value, or an equation when it is computed using more variables. This example uses a given flowrate to obtain a mean velocity which is multiplied by a constant.  

 

c) Maximum radius (R)

Again, this can be a value or an equation. Here is the example where it is calculated from the circle area (A = pi*R^2): 

2.  Goto boundary conditions > Inlet. Assign the velocity profile. You can continue with your modelsetup or if you want a quick check, skip step 3. 

 

3.  Initializethe model. If you use the Standard initialization, be aware that the velocity in the flow direction cannot be zero. In this example,the Hybrid Initialization was used. 

 

4.  Createa contour plot of velocityon the inlet section. You must see something like the contour shown below.  

A second option for verifying the velocity profile is using a line. On the tree, go to Results > Surfaces > New > Line/Rake. The line must cover the pipe diameter through the circle center. Next, go to Results > Plots > XY Plot > Right-Click and new. Select the options shown. Finally, click on Save/Plot. 

 

You can repeat this procedure to use any other velocity profile based on an equation.