[Pororo]

Hello, guys

I'm using the star CCM+.
I have few questions.

Description: On my modeling(the modeling is long tube pipe that has different radius between inlet and outlet), the condition is pressure inlet and pressure outlet. Through the condition, I want to know a velocity in the tube.

To get the result, I give pressure value under the initial condition and pressure outlet value is on under the Regions, outlet. At my inlet condition values are zero.

But, when I run the simulation, the result seems highly different with my theoretical data.

To get the good data, how do I modify the condition?


2. I want to know what's a stagnation inlet.

[LuckyTran]

1. Put in the right conditions. You need to tell us what are the real conditions you want to model and what settings you have used. Also don't forget about the reference pressure.


2. In CFD you cannot specify static pressure at an inlet because you need to respect the laws of physics. At a stagnation inlet you are specifying the stagnation pressure or total pressure which is the sum of static pressure head and dynamic head, and will be a slightly higher value than the inlet static pressure.

[Pororo]

I want to analyze if I give 4bar pressure at the inlet, I want to measure a velocity in the pipe. The outlet pressure is same as ATM (1bar)

[LuckyTran]

So, typically this would mean you use a stagnation inlet and pressure outlet.

The default reference pressure is 1 atm. So you should specify an inlet stagnation pressure of 3 bar and outlet pressure of 0 bar because they are gauge pressures. If you have changed the reference pressure then you should change your pressures accordingly.

[Pororo]

Thank you.