[Nadaaaa22]

I’m working in a natural convection flow, I would like to know using the incompressible in the ideal gas flow how can it affects the Navier-stokes equations? . Another question, which solver (segregated/coupled) should I use for natural convection of incompressible ideal gas and for normal ideal gas?.

[LuckyTran]

The density in the incompressible ideal gas is taken at the operating pressure and doesn't change with pressure.


Both solvers work.

[Nadaaaa22]

Originally Posted by LuckyTran

The density in the incompressible ideal gas is taken at the operating pressure and doesn't change with pressure.


Both solvers work.

Thank you for your answer
I have a question why in the incompressible ideal gas the governing equations can be decoupled but they can’t in the ideal gas?.

[LuckyTran]

The equations are coupled. How to solve a system of coupled equations is another matter. You can take a divide-and-conquer approach (the segregated approach) or you can try to figure out a way to solve the coupled system.

[Nadaaaa22]

Originally Posted by LuckyTran

The equations are coupled. How to solve a system of coupled equations is another matter. You can take a divide-and-conquer approach (the segregated approach) or you can try to figure out a way to solve the coupled system.

How can we solve it using segregated approach if they depend on each other?.sorry i’m getting lost

[LuckyTran]

Originally Posted by Nadaaaa22

How can we solve it using segregated approach if they depend on each other?.sorry i’m getting lost

Let's say you have a temperature-based formulation for energy. So the variables you're solving for are density, pressure&velocity, and temperature.


In the segregated approach, you could assume a background temperature field (by taking the latest guess) and then solve the continuity and momentum equations for an updated density, velocity, and pressure. Then you take your newest density, velocity, and pressure, and solve the energy equation for a new temperature field. Voila, you've solved a coupled system of equations using a segregated approach.