How to model smoke in cfx?

atulpat · January 28, 2014, 08:03

Hello friends..........
I am working on smoke analysis. Regarding smoke analysis I read discussions available on CFD online. I got some information that there are two methods- Passive and Active scalar. I want to define smoke as a pure substance material as per active scalar method but I don't know the thermal properties of the smoke (smoke from burning car).

Please help me..
Thanks in advance

ghorrocks · January 28, 2014, 17:01

I presume you mean the difference between your passive and active scalar is the passive one does not affect material properties, but the active one affects the material properties of the gas.

If you do not know the properties of the smoke then your only choice is passive scalar approach.

atulpat · January 28, 2014, 23:37

Thanks Gorrocks
Actually, Passive scalar method is simple and we have to use additional variable for creating the smoke. Also it is explained in CFX tutorial.
Now, I am thinking to use Active scalar method in order to get knowledge of active scalar method but I don't the properties of the smoke. If you have any idea then please help me.

ghorrocks · January 28, 2014, 23:45

You will have to research the literature on the physical properties of the smoke for the type of fire you are modelling. You will need to go to your library for this (or google or anything which allows you to read journal articles).

As I said, if you do not know the physical properties of your smoke then you will be forced to use the simple passive approach. This is because the only property it requires is diffusivity.

January 28, 2014, 08:03	How to model smoke in cfx?	#1
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 12	Hello friends.......... I am working on smoke analysis. Regarding smoke analysis I read discussions available on CFD online. I got some information that there are two methods- Passive and Active scalar. I want to define smoke as a pure substance material as per active scalar method but I don't know the thermal properties of the smoke (smoke from burning car). Please help me.. Thanks in advance

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January 28, 2014, 17:01		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,711 Rep Power: 143	I presume you mean the difference between your passive and active scalar is the passive one does not affect material properties, but the active one affects the material properties of the gas. If you do not know the properties of the smoke then your only choice is passive scalar approach.

January 28, 2014, 23:37		#3
atulpat New Member Atul Patil Join Date: Jul 2013 Location: India Posts: 26 Rep Power: 12	Thanks Gorrocks Actually, Passive scalar method is simple and we have to use additional variable for creating the smoke. Also it is explained in CFX tutorial. Now, I am thinking to use Active scalar method in order to get knowledge of active scalar method but I don't the properties of the smoke. If you have any idea then please help me.

January 28, 2014, 23:45		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,711 Rep Power: 143	You will have to research the literature on the physical properties of the smoke for the type of fire you are modelling. You will need to go to your library for this (or google or anything which allows you to read journal articles). As I said, if you do not know the physical properties of your smoke then you will be forced to use the simple passive approach. This is because the only property it requires is diffusivity.