Learning Forum

[Mepal]

Hello all,

I've been facing with an easy case, but I cannot fix it now.

I created a close box. there are only air and oxygen inside it.

I used an Eulerian multiphase with a default setting from Fluent.

Inside a box, air is at an upper region, and oxygen is at a lower region at an initial stage.

After some iteration, nothing happen. No mixing between air and oxygen.

There are gases, so they should be mixed together. I assume that Fluent think they are two immisible fluid with a different density, Am I right?

Are there any general suggestion to handle it?

Thank you in advance.

[Rob]

Fluent doesn't identify whether something will mix based on whether it's a gas/liquid but on what models are set and what the fluid properties are. If the two materials have densities such that there the lighter phase is on top then nothing much will happen: there is no diffusion as they're separate phases. 

If you had two species in a mixture then diffusion would occur, but, you'd also not see species stratification if mixing two materials with very different densities. 

[Mepal]

Thank you Rob, I followed your suggestion and I was work well.