Learning Forum

[CFDisGreat]

Hello,

I want to model natural gas that passes through a pipe. I wonder if you can help me with that.

I want to define the volumetric weight of each component (8 gases and water liquid) in my natural gas formulation (for instance 8% CH4, 2% B, 1.75% A, etc.)

Which model I should consider?

 

 VoF? Mixing? Species transport? compressible or incompressible?

 

THank you,

[Raef.Kobeissi]

Compressible, VOF. Do you have any phase change?

[CFDisGreat]

Yes.

What if I have water as vapor along with other gaseous components? In that case, I may not use VOF as they all share one phase (gaseous) and use the Specious model. Right? How do I model natural gas (different gaseous components with different volumetric weights) in a pipe?

In fact, vapor (water) in natural gas will change its phase to liquid and will drain out of the pipe.

 

Regarding compressibility, if Mach number is around 0.5, pressure-based solver won't work? In fact, as it passes 0.3, should we switch to a density-based solver?

 

Thank you for your time.

[Rob]

If you want to look at condensation you need to run through basic models first: it's not easy. You also need to decide if you really need to model all species or whether you can consider "gas" and "water vapour" as one phase and "water liquid" as the other. 

Pressure based solver is good to about Mach 2-3 and Density based doesn't work with most multiphase models. It may mean the gas is compressible though.