[Einzo]

Hello, i'm actually working on a project where i study the feasablity of creating flow in a LPG pipe using natural gas & i want to simulate this with fluent.

So i wanted to know if it was feasable with fluent & if so, is it hard to do for a beginner like me.

[LuckyTran]

I have no idea what is going on here. What are you trying to model?

[Einzo]

The black pipe in the image is full of LPG in a static state (no flow) under a pressure of 20bars (300psi) & i want to simulate what happens if we inject natural gas under a pressure of 40bars(600psi) as shown in the image, to see the behaviour of both fluids & see if there will be natural gas dessolved in LPG under the effect of the high pressures.

Basically i want to see if i will be able to push the LPG using the natural gas.

It is frequently done in the oil & gas industry using a pig to separate the fluids from each other, i want to simulate what happens if there is direct contact between the fluids, as the use of pig is impossible in some situations.

[LuckyTran]

Originally Posted by Einzo

Basically i want to see if i will be able to push the LPG using the natural gas.

Well the answer is, of course you can. Because of continuity. You don't need any fancy thermodynamics/fluid mechanics to determine that, just kinematics.

You'll need to do a multiphase simulation for liquid and gas phases. You'll also need to enable the species solver if you want to look into transport of NG into LPG. This part of the simulation is somewhat easy to do.

The problem with these types of simulations where you have a suddenly imposed boundary condition is, in order to do it with a high degree of accuracy you need an extremely fine grid to resolve the moving front (the gas|liquid interface as it passes through the domain).

Finally, depending on what physical phenomena you are trying to capture at the gas|liquid interface, you might run into some trouble. Surface tension effects are handled with the multiphase options in Fluent, but if you have anything complicated going on there, you might not be able to do it in Fluent.