[notecool24]

Hi, I am new in FLUENT

Form the picture I have attached, I made an experiment of fluid flow in the long tube (2.6 mm in diameter) and I used two pressure catheters to measure pressure from each part (45 mm far away from each pressure sensor).

So, in my FLUENT I created a pipe that has length only 45 mm and try to set boundary conditions at inlet and outlet as pressure-inlet/outlet and insert pressure data that I collected from experiment to check that the result which is velocity will be the same.

At pressure-Inlet I set Gauge total pressure to 1866 pascal (14 mmHg)
At pressure-Outlet I set Gauge pressure to 1200 pascal (9 mmHg)
At operating pressure, which I still not 100% understand in it , I set it as 0.

However, the result (Flow in pipe) from Fluent is not the same from experiment and it seem that the pressure at inlet was dropped to be like around 12750 ??

What make this simulation wrong ? Or setting pressure from experiment as inlet and outlet of the pipe are the wrong idea for FLUENT ? Also how to make the pressure at inlet doesn't drop too much or I need to set something to make FLUENT known that this inlet pressure must remain constant ?

[kad]

The input for pressure inlet is total pressure. In your experiment you measured only static pressure. Operating pressure btw. is obsolete for incompressible flow.

[notecool24]

So, what is the best boundary condition for me to put into this model at inlet and outlet.I tried to put velocity inlet (because I know the flow in the tube) and keep the outlet-pressure the same from the experiment. However, the result from simulation show difference in pressure inlet compared to real experiment.

[kad]

I guess your velocity distribution is uniform over the inlet. So it is no wonder results are not good.

For fully developed pipe flow try periodic boundary condition with mass flow input: http://aerojet.engr.ucdavis.edu/flue...g/node1355.htm