Simulation of fog clouds due to ambient air vaporizers.

nextdaydie · April 24, 2013, 01:43

Hi.
I'd like to ask somequestions about fog clouds in CFX.

I'm trying to make fog clouds aorund vaporizers by using CFX

http://www.sciencedirect.com/science...50423010000951

In that reference paper, he did it using Star CCM and there are no detailed sources about it so it is hard to try using CFX.

he said he used User Define Function to implement the phase chang between water vapor and fog droplets, as defined by the psychrometric model equations.

how can I use UDF about the psychrometric model equations?
Should I make two or three fluids such as vapor, air and water....

Could you please give me some advices about it?

I can send you that paper if you want.

help me..

ghorrocks · April 24, 2013, 07:34

This is a complex model, so do not underestimate it.

To do this model you are going to have to set up a number of careful phase interactions. This may well not need a UDF like Star needs, you may well be able to do it entirely in the GUI. But I am not sure on this, you will have to check for yourself.

I recommend you do all the tutorials in CFX especially the multiphase ones, and then some training on the CFX multiphase models. The course I attended years ago was a very good introduction to the CFX multiphase models.

As for whether this is a 2 or 3 fluid model - there are many approaches and either can work. But they all have their own subtle issues to resolve. So unless you can work out the differences between modelling this as a 2 or 3 phase model yourself you do not have a hope in getting this model working. Sorry for being blunt, but it is the truth.

April 24, 2013, 01:43	Simulation of fog clouds due to ambient air vaporizers.	#1
nextdaydie New Member Yoonsub Eom Join Date: Jun 2012 Posts: 1 Rep Power: 0	Hi. I'd like to ask somequestions about fog clouds in CFX. I'm trying to make fog clouds aorund vaporizers by using CFX http://www.sciencedirect.com/science...50423010000951 In that reference paper, he did it using Star CCM and there are no detailed sources about it so it is hard to try using CFX. he said he used User Define Function to implement the phase chang between water vapor and fog droplets, as defined by the psychrometric model equations. how can I use UDF about the psychrometric model equations? Should I make two or three fluids such as vapor, air and water.... Could you please give me some advices about it? I can send you that paper if you want. help me..

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April 24, 2013, 07:34		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	This is a complex model, so do not underestimate it. To do this model you are going to have to set up a number of careful phase interactions. This may well not need a UDF like Star needs, you may well be able to do it entirely in the GUI. But I am not sure on this, you will have to check for yourself. I recommend you do all the tutorials in CFX especially the multiphase ones, and then some training on the CFX multiphase models. The course I attended years ago was a very good introduction to the CFX multiphase models. As for whether this is a 2 or 3 fluid model - there are many approaches and either can work. But they all have their own subtle issues to resolve. So unless you can work out the differences between modelling this as a 2 or 3 phase model yourself you do not have a hope in getting this model working. Sorry for being blunt, but it is the truth.