Learning Forum

[joanlopez654321000]

We are working on a 3d problem:  2.6mm side square section channel of 380mm length, and 3d inlets and oulets

We have got 3 inlets that take 3 liquids to this main channel (Multiphase-VOF)

The liquids have 3 different densities that stratify while moving

They move very slow along the main channel (approx. at 0.1mm/s)

We use transient because at the end we are interested on looking what happens when we inject particles inside de channel (DPM)

We initialize the system with Hybrid (t=0. Everything full of one of our liquids)

We take 20 hours of calculations for filling the channel with transient mode. After that time, we can inject particles and see what happens.

The flow rates of the 3 liquids are different and not constant

  

The question:

Is there any way faster of filling the device with the 3 liquids? We are not interested on what happens while filling.

Could we use steady until filling and use transient after that point? 

[Rob]

Steady isn't likely to work well, but if you know roughly where the three fluids will be then the Patch option is a good way to speed up reaching the equilibrium condition. 

Do you expect the three streams to intermingle whilst stratifying or do they remain separate all the way through? I ask as VOF assume you're tracking the free surface so the model isn't designed for diffuse fluid interfaces. 

[joanlopez654321000]

In theory three streams remain separate while moving
Could you give me information for patching in 3d with an imported CAD?
Maybe you must define a multibody geometry at CAD?

Thanks in advance

 

[Rob]

No, have a look at the Registers in Fluent. If you break the model up in CAD it's easier to assign the patch to a fluid region, but it's not a requirement. 

[joanlopez654321000]

ok
Thanks a lot !

[Rob]

You're welcome. There's a lot to Fluent that's not obvious, and a fair bit that can be misused, or has been altered following our misuse, to let us do things that make modelling quicker/easier.