Dispersed Fluid Simulation with Interface between domains

alexksei · December 19, 2018, 11:19

Hi,

I am trying to simulate a flow of air with dispersed fluid (water). Dispersed phase (water) is 5% of Volume Fraction at the INLET.

I have two domains (see picture):

https://www.dropbox.com/s/knnl6an378...hot_2.png?dl=0

static and rotational and between them I use FROZEN ROTOR interface. I have problems with CFX to solve this case (overflow error at 6th iteration each time I run the simulation).

The same case but without dispersed fluid works well.

I will be grateful for any good advice on how to solve this.

ghorrocks · December 19, 2018, 17:37

FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

If you make the rotating domain stationary does it converge?

alexksei · December 20, 2018, 02:58

Quote:

Originally Posted by ghorrocks

FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

If you make the rotating domain stationary does it converge?

I did several cases:

1. Without dispersed phase (AIR only), stationary domain- converged
2. Without dispersed phase (AIR only), rotating domain- converged
3. Dispersed WATER and continious AIR, only one domain, no interfaces - converged
4. Dispersed WATER and continious AIR, 2 domains, interfaces - OVERFLOW error

From these cases it seems the problem is about interfaces between domains and only when dispersed phase is introduced. When there is no dispersed phase everything works well.

Opaque · December 20, 2018, 09:29

Dear Alexsei,

You have not tried the combination of

Dispersed WATER and continuous AIR, 2 domains (both stationary) with interfaces.

You can either set the Rotating domain to Stationary, or set the Angular Velocity to 0. They are different tests, so both results will help.

That is what Glenn asked.

AtoHM · December 20, 2018, 09:59

Have you tried initialising/interpolating your converged solution onto the one that doesn't work prior to starting?
This helped me get rid of some problems, the first steps during the run are sometimes critical. Maybe your setup works fine with a good initial guess instead of starting from scratch.

December 19, 2018, 11:19	Dispersed Fluid Simulation with Interface between domains	#1
alexksei New Member Aleksei Join Date: Jun 2018 Posts: 24 Rep Power: 8	Hi, I am trying to simulate a flow of air with dispersed fluid (water). Dispersed phase (water) is 5% of Volume Fraction at the INLET. I have two domains (see picture): https://www.dropbox.com/s/knnl6an378...hot_2.png?dl=0 static and rotational and between them I use FROZEN ROTOR interface. I have problems with CFX to solve this case (overflow error at 6th iteration each time I run the simulation). The same case but without dispersed fluid works well. I will be grateful for any good advice on how to solve this.

December 19, 2018, 17:37		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F If you make the rotating domain stationary does it converge? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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December 20, 2018, 09:29		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	Dear Alexsei, You have not tried the combination of Dispersed WATER and continuous AIR, 2 domains (both stationary) with interfaces. You can either set the Rotating domain to Stationary, or set the Angular Velocity to 0. They are different tests, so both results will help. That is what Glenn asked.

December 20, 2018, 09:59		#5
AtoHM Senior Member M Join Date: Dec 2017 Posts: 703 Rep Power: 13	Have you tried initialising/interpolating your converged solution onto the one that doesn't work prior to starting? This helped me get rid of some problems, the first steps during the run are sometimes critical. Maybe your setup works fine with a good initial guess instead of starting from scratch.