Multiphase Material Morphology Choice

oliveira1820 · August 17, 2018, 02:23

I´m simulating the phase change between liquid water and vapor. Therefore in my simulation I'l have air, liquid water and gaseous water.

I´m using the Thermal Phase Change Model and the Particle Model and is a non-equilibrium phase change simulation.

What is the best approach to my simulation:??

1- Continous fluid - Liquid Water and Dispersed fluid - Water Vapor and Dispersed Fluid - Air

or

2- Continous Fluid - Mixture of Liquid Water and Water Vapor and Dispersed Fluid - Mixture of Water Vapor and Air

ghorrocks · August 19, 2018, 06:07

Option 2 is the better approach. (because option 1 will have two gas phases, but you only have one gas phase)

oliveira1820 · August 20, 2018, 00:25

How should it be my approach?

1 - Use two variable composition mixtures: one liquid with liquid water and "liquid" water vapour and one gaseous with air and water gaseous vapour?

2 - Use liquid water as a liquid and air and water vapour as a gaseous variable composition mixture?

( Notice that in all the approaches I define liquid water, water vapour and, the correspondingly homogenous binary mixture in materials with IAPWS tables)

Or do you suggest other approach?

ghorrocks · August 20, 2018, 01:57

Option 2 is the physically correct approach. But I have never done the model you propose so cannot say from experience exactly how to do it. So start from the physically correct approach and only consider other options if that does not work.

oliveira1820 · August 20, 2018, 02:13

I noticed that when I use variable composition mixture i can´t enable Mass Transfer by Phase Change (Only Cavitation and Specified Mass Transfer) and therefore the Thermal Phase Change Model . I can only do this with the liquid water, air and water vapour separated, should I work with one continuous and two dispersed?

ghorrocks · August 20, 2018, 07:13

I was wondering if that was the case. In that case you are going to have to do as you suggest, but validate it carefully to ensure it is still valid. It would also be wise to ask ANSYS support for some guidance here. They have many more examples available than the tutorials so might have some examples of this case to work from.

August 17, 2018, 02:23	Multiphase Material Morphology Choice	#1
oliveira1820 Senior Member Pedro Oliveira Join Date: Feb 2018 Location: Portugal Posts: 109 Rep Power: 8	I´m simulating the phase change between liquid water and vapor. Therefore in my simulation I'l have air, liquid water and gaseous water. I´m using the Thermal Phase Change Model and the Particle Model and is a non-equilibrium phase change simulation. What is the best approach to my simulation:?? 1- Continous fluid - Liquid Water and Dispersed fluid - Water Vapor and Dispersed Fluid - Air or 2- Continous Fluid - Mixture of Liquid Water and Water Vapor and Dispersed Fluid - Mixture of Water Vapor and Air

August 19, 2018, 06:07		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Option 2 is the better approach. (because option 1 will have two gas phases, but you only have one gas phase) __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

August 20, 2018, 01:57		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Option 2 is the physically correct approach. But I have never done the model you propose so cannot say from experience exactly how to do it. So start from the physically correct approach and only consider other options if that does not work. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

August 20, 2018, 07:13		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I was wondering if that was the case. In that case you are going to have to do as you suggest, but validate it carefully to ensure it is still valid. It would also be wise to ask ANSYS support for some guidance here. They have many more examples available than the tutorials so might have some examples of this case to work from. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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August 20, 2018, 00:25		#3
oliveira1820 Senior Member Pedro Oliveira Join Date: Feb 2018 Location: Portugal Posts: 109 Rep Power: 8	How should it be my approach? 1 - Use two variable composition mixtures: one liquid with liquid water and "liquid" water vapour and one gaseous with air and water gaseous vapour? 2 - Use liquid water as a liquid and air and water vapour as a gaseous variable composition mixture? ( Notice that in all the approaches I define liquid water, water vapour and, the correspondingly homogenous binary mixture in materials with IAPWS tables) Or do you suggest other approach?

August 20, 2018, 02:13		#5
oliveira1820 Senior Member Pedro Oliveira Join Date: Feb 2018 Location: Portugal Posts: 109 Rep Power: 8	I noticed that when I use variable composition mixture i can´t enable Mass Transfer by Phase Change (Only Cavitation and Specified Mass Transfer) and therefore the Thermal Phase Change Model . I can only do this with the liquid water, air and water vapour separated, should I work with one continuous and two dispersed?