How do we post-process forward and backward rates of a reversible reaction in CFX.
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A reversible Reaction can be set in CFX via two methods: (a) Explicitly giving the forward and backward Rate (b) Equilibrium Option The `{Reaction}.Molar Reaction Rate` reported by CFX is the effective net rate (forward ` backward) for a reversible reaction. When the backward rate dominates it will be negative. In the solver we currently only calculate the net rate. If one needs to post-process forward and backward reaction rates separately, then the best solution is to setup the reversible reaction as two separate reactions; one forward and one backward. Of course, this is not possible when using the `Equilibrium` option for the backward rate. However, this can be worked around as follows (need to do this for each reaction with equilibrium backward rate): (1) Setup the desired reversible reaction with forward and backward reaction rates either via "Equilibrium option" or by explicitly giving the "forward and backward rates". (2) Add a second `dummy` reaction, which is a copy of the first reaction but with the following differences: - Set stoichiometric coefficients to zero for all reactants and products - Make sure reaction orders are specified for all reactants (important!), if unknown set equal to stoichiometric coefficient. - Disable the backward reaction rate by un-checking the box for `Backward Reaction Rate` Because all stoichiometric coefficients in the `dummy` reaction are zero, it will not generate any source terms. However, a reaction rate will be calculated and written to the result file ` this reaction rate will be equal to the forward reaction of the `real` reaction. The backward reaction rate can then be calculated as ({real reaction}.Molar Reaction Rate ` {dummy reaction}.Molar Reaction Rate). |
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