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4.5 Discussion
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attachment and detachment rate constants. It is of interest to evaluate the
degree of non-equilibrium using these relations. An important criterion for
the classification of reactive transport problems is the Damkhler number, Da,
which is the ratio of the advection time scale (L/v) to the typical time scale
of the adsorption (defined as (1/k det )), with L being loosely defined as some
characteristic length of the domain
Da = kc det L
v
(4.20)
As a rule of thumb, adsorption is considered to be (quasi) equilibrium, if
Da >> 1, and kinetic for Da