Help! reaction udf for multiphase

m_amiri · January 12, 2015, 09:05

Dear all
I would like to write a reaction in in two phase gas solid eulerian-granular model with fluent. my reaction mechanism is not in the Arrhenius form. I have two general question?
1. in udf macros there are some which related to reaction such as heterogeneous reaction, VR_Reaction, Net_Rate_Reaction, Mass Transfer Source Therm. which one is appropriate for this case?
2. when there are one gas mixture and one solid mixture (which solids are defined as fluid in material because of Euler_Gran Model), considering VR_Reaction Macro, how I can access to species properties in each phase such as mass fraction or molecular weight,...?
Any help will be much appreciated. Many thanks!

Sun · January 14, 2015, 04:36

This is how I would be looking at the kinetics-related problem. Let's assume you are solving a PDE to represent the conversion of your reactant and the diffusion is not important. The form of your PDE is then:

$\frac{\partial {X}}{\partial {t}} + \nabla \cdot (XU) = source$

In this case you need to define a UDS (user defined scalar) to identify the conversion's behavior of X in time and space. The source term can then be coded using DEFINE_SOURCE macro (Arrhenious or non-arrhenious, as long as you have an expression for that).

Regarding to your second question, as far as I understand, I think you are looking for macros such as C_YI(c,t,i) and etc. Have a look at tables 3.2.8 to 3.2.16 for more details.
cheers!

m_amiri · January 15, 2015, 10:54

Thanks for your reply.
my problem is in multiphase udf macros such as VR_Rate how can i access to properties of each species in each phase.
Thanks.

January 12, 2015, 09:05	Help! reaction udf for multiphase	#1
m_amiri New Member Join Date: Jan 2015 Posts: 3 Rep Power: 11	Dear all I would like to write a reaction in in two phase gas solid eulerian-granular model with fluent. my reaction mechanism is not in the Arrhenius form. I have two general question? 1. in udf macros there are some which related to reaction such as heterogeneous reaction, VR_Reaction, Net_Rate_Reaction, Mass Transfer Source Therm. which one is appropriate for this case? 2. when there are one gas mixture and one solid mixture (which solids are defined as fluid in material because of Euler_Gran Model), considering VR_Reaction Macro, how I can access to species properties in each phase such as mass fraction or molecular weight,...? Any help will be much appreciated. Many thanks!

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January 14, 2015, 04:36		#2
Sun Senior Member Join Date: Nov 2010 Posts: 103 Rep Power: 16	This is how I would be looking at the kinetics-related problem. Let's assume you are solving a PDE to represent the conversion of your reactant and the diffusion is not important. The form of your PDE is then: $\frac{\partial {X}}{\partial {t}} + \nabla \cdot (XU) = source$ In this case you need to define a UDS (user defined scalar) to identify the conversion's behavior of X in time and space. The source term can then be coded using DEFINE_SOURCE macro (Arrhenious or non-arrhenious, as long as you have an expression for that). Regarding to your second question, as far as I understand, I think you are looking for macros such as C_YI(c,t,i) and etc. Have a look at tables 3.2.8 to 3.2.16 for more details. cheers!

January 15, 2015, 10:54		#3
m_amiri New Member Join Date: Jan 2015 Posts: 3 Rep Power: 11	Thanks for your reply. my problem is in multiphase udf macros such as VR_Rate how can i access to properties of each species in each phase. Thanks.