Simulating Silica Evaporation in CFX

Deepus · January 22, 2018, 02:18

Hi All,

My CFD problem is to simulate evaporation of water using hot air. I was doing this in CFX.

While defining the fluid properties of water, there are options like continuous fluid, dispersed fluid, droplets (phase change). I am unsure of which option to select. The mass rate and temperature of air is good enough to convert the entire water to water vapor.

Can anybody explain the differences in these cases.

Thanks in advance..

ghorrocks · January 22, 2018, 05:02

The options you describe are multiphase models, not fluid properties. Continuous fluid and dispersed fluid invoke a Eularian multiphase model and droplets (phase change) invoke a Lagrangian multiphase model.

To choose an appropriate multiphase model you need to know what state the air and water are in - droplets? foam? mist? bubbles? free surface?

Deepus · January 23, 2018, 05:23

Hi Glen,

Thank you for your response.

I need to simulate water and air mixing in either CFX or Fluent. Water (0.1 kg/s) at 30C mixes with Air (1 kg/s) at 550C. I want to see at what point water turns into vapor and what is the final temperature.

I gave multiple phase option. But I am unable to define the mass flow rates. I am also unable to define the inlet fluid. Can you please help me out.

Thank you for your help in advance...

Regards,
Deepak

Gert-Jan · January 23, 2018, 08:25

Why are you trying to model these very complicating physics. I would suggest to start with hand calculations, then experiments and then CFD.

ghorrocks · January 23, 2018, 16:43

I agree with Gert-Jan. You can do this with a hand calculation. Is there some reason a hand calculation is not suitable.

January 22, 2018, 02:18	Simulating Silica Evaporation in CFX	#1
Deepus New Member Kerala Join Date: Jan 2018 Posts: 2 Rep Power: 0	Hi All, My CFD problem is to simulate evaporation of water using hot air. I was doing this in CFX. While defining the fluid properties of water, there are options like continuous fluid, dispersed fluid, droplets (phase change). I am unsure of which option to select. The mass rate and temperature of air is good enough to convert the entire water to water vapor. Can anybody explain the differences in these cases. Thanks in advance..

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January 22, 2018, 05:02		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	The options you describe are multiphase models, not fluid properties. Continuous fluid and dispersed fluid invoke a Eularian multiphase model and droplets (phase change) invoke a Lagrangian multiphase model. To choose an appropriate multiphase model you need to know what state the air and water are in - droplets? foam? mist? bubbles? free surface?

January 23, 2018, 05:23		#3
Deepus New Member Kerala Join Date: Jan 2018 Posts: 2 Rep Power: 0	Hi Glen, Thank you for your response. I need to simulate water and air mixing in either CFX or Fluent. Water (0.1 kg/s) at 30C mixes with Air (1 kg/s) at 550C. I want to see at what point water turns into vapor and what is the final temperature. I gave multiple phase option. But I am unable to define the mass flow rates. I am also unable to define the inlet fluid. Can you please help me out. Thank you for your help in advance... Regards, Deepak

January 23, 2018, 08:25		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	Why are you trying to model these very complicating physics. I would suggest to start with hand calculations, then experiments and then CFD.

January 23, 2018, 16:43		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	I agree with Gert-Jan. You can do this with a hand calculation. Is there some reason a hand calculation is not suitable.