## Fluids

#### Second degree curve as an initial condition!

• Abdou11
Subscriber

Hello,

currently i am doing a simulation where i am simulating a 2d model of an emptying process which consists of a supply (inlet ) to a tank which is connected to a pipe to empty it. At t=0s, the tank and the pipe are filled with water.

So I setup all the boundary conditions, but when I got to the point where I need to specify the initial velocity perturbation of full flow inside the pipe, I was only able to initialize it 'with a constant value, but as you may know, the velocity distribution inside a pipe at full flow is a 2nd degree curve.

How can I assign a 2nd degree curve condition as an initialization value?

• DrAmine
Ansys Employee
Use an Expression to have the proper initialization? I do not understand the 2nd degree condition: can you please tell more?
• Abdou11
Subscriber
yes because the velocity distribution in a fully formed flow inside a pipe is an equation for a 2nd degree curve, as it shown in the picture.

• DrAmine
Ansys Employee
Ah if that is what you mean with second order..
Okay for that you need to create an Expression to input a parabolic velocity profile. In Fluent User's Guide you will find a detailed example how to do that.
• Abdou11
Subscriber
Thank you for the information, i will look it up
• DrAmine
Ansys Employee
Welcome!