Binary Diffusion Coefficient

July 19, 2005, 09:56

Hi everyone!

Does anybody has experience in setting binary diffusion coefficient for Kinematic Diffusivity in CFX 5.7.1?

I read about USEDIF fortran subroutine but is not supported on this release of CFX (it's for CFX4 only).

Thanks in advance for any suggestion.

July 22, 2005, 10:01

Constant diffusivity is set under the fluid properties. If you want a variable diffusivity, set it to a CEL variable, and calculate the variable value in CEL as a function of temperature, etc.

Jeff

July 26, 2005, 04:04

Thank you Jeff!

Can you also suggest a source (or more than one) for appropriate diffusion coefficient values for methane-air combustion?

I found some data on the web but not sure about that.

I'm simulating combustion of methane-air mixture including CHT effects with solid. In some cases simulations shows flashback phenomena, not in according with sperimental data.

So i'm trying to find a way to raise the flame front (which usually is really low in simulations) in order to avoid flashback (maybe due to inappropriate transport properties description of the species).

Is this reasoning correct?

What else could raise flame front?

Thanks.

aerospace1365 · July 1, 2012, 13:11

hello dear jeff
I want to simulate combustion of h2/air in fluent and I really need to its transport properties. have u any data about like chemKINE file.
best regards.

July 19, 2005, 09:56	Binary Diffusion Coefficient	#1
Frank Guest Posts: n/a	Hi everyone! Does anybody has experience in setting binary diffusion coefficient for Kinematic Diffusivity in CFX 5.7.1? I read about USEDIF fortran subroutine but is not supported on this release of CFX (it's for CFX4 only). Thanks in advance for any suggestion.

July 22, 2005, 10:01	Re: Binary Diffusion Coefficient	#2
Jeff Guest Posts: n/a	Constant diffusivity is set under the fluid properties. If you want a variable diffusivity, set it to a CEL variable, and calculate the variable value in CEL as a function of temperature, etc. Jeff

July 26, 2005, 04:04	Re: Binary Diffusion Coefficient	#3
Frank Guest Posts: n/a	Thank you Jeff! Can you also suggest a source (or more than one) for appropriate diffusion coefficient values for methane-air combustion? I found some data on the web but not sure about that. I'm simulating combustion of methane-air mixture including CHT effects with solid. In some cases simulations shows flashback phenomena, not in according with sperimental data. So i'm trying to find a way to raise the flame front (which usually is really low in simulations) in order to avoid flashback (maybe due to inappropriate transport properties description of the species). Is this reasoning correct? What else could raise flame front? Thanks.

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July 1, 2012, 13:11		#4
aerospace1365 New Member faramarz Join Date: Feb 2012 Location: tehran Posts: 10 Rep Power: 14	hello dear jeff I want to simulate combustion of h2/air in fluent and I really need to its transport properties. have u any data about like chemKINE file. best regards.