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Setting Mass and Energy sources in fluent

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Old   February 12, 2006, 20:36
Default Setting Mass and Energy sources in fluent
  #1
Amr
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Hi there,

I am simulating a 2D smoke dispersion event in an atrium with fluent. The smoke is to be modelled as mass and energy source. I have finished the grid and looked into the fluent manual that says that sources need to be defined at zones (i.e. not at boundary edges). I want to set my source at 1 meter diameter circle at the ground level in my model. Could anybody give me a hand on what are the steps required for so ?.

Many Thanks, Amr
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Old   February 13, 2006, 11:14
Default Re: Setting Mass and Energy sources in fluent
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Milo
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Hi Amr! You first need to include the circular source in your mesh and then use the fixed values option in boundary condition for the fluid panel to impart velocity to smoke. You can also use fan boundary condition at your circular source to model it as mass source.
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Old   February 13, 2006, 14:35
Default Re: Setting Mass and Energy sources in fluent
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Amr
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Hi Milo, Thanks for your answer. Actually, I'd like to know how to create this source!. My model is a 2D rectangular room with one face (one fluid zone). I am thinking of creating a mass and energy source at the bottom edge (grade level). To do that, I grasped that I need to create a separate fluid zone on the bottom edge. I have no clue how to create this source especially that I discovered that the sources need fluid zones (separate zone in my case). Could you instruct me how to do this?.

Do you think a fixed value is better than defining a source? Why is that? Thanks again !

Amr
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Old   February 13, 2006, 15:59
Default Re: Setting Mass and Energy sources in fluent
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Amr
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Further to our discussion, I have read in some material that I need to create a rectangular face at the bottom of my room -to simulate a fire box for example 1m by 0.25m- then, I define this face as a fluid zone in which I set my sources of mass and heat. Now, if this is the best practice, what is the approperiate boundary conditions set for the edges of my fire box rectangular face? Do I use interface, wall, ..etc? Note that I am putting a window at one wall and an outlet vent at the ceiling.

Amr
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Old   February 13, 2006, 23:18
Default Re: Setting Mass and Energy sources in fluent
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Milo
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To answer your first question, draw the geometry of the source above the bottom edge and use split command (in Gambit) to split the rectangular room face with the source face. Now you can mesh both these faces separately and define different fluid zones in each.

In the fixed values option, fluent will not solve transport equations for that fluid zone and the fixed values will be used to solve for tranport in rectangular room. If you are primarily concerned only with transport in room, then you may use this feature.
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Old   February 13, 2006, 23:21
Default Re: Setting Mass and Energy sources in fluent
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Milo
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Yeah, you need to define the boundary condition for the inner edges of the firebox as interior.
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Old   February 23, 2006, 07:36
Default Re: Setting Mass and Energy sources in fluent
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Amr
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Many thanks Milo. I have posted a new message today titled "Smoke simulation inside atriums". Take a look in case you can help.

Thanks again, Amr
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