10.4122/1.1000000566
Darvini, Giovanna
Giovanna
Darvini
g.darvini@univpm.it
Salandin, Paolo
Paolo
Salandin
sala@univpm.it
Darvini, Giovanna
Giovanna
Darvini
g.darvini@univpm.it
Examples of subsurface solute spreading driven by inhomogeneous velocity fields
XVI International Conference on Computational Methods in Water Resources
2006
2006
Most of solutions of flow and transport problems available in literature are
obtained under assumptions of stationarity of flow field and/or ergodicity of
transport, even though in real-world analyses these hypotheses cannot be always
verified. For instance, into problems that are met in practical applications, the
statistics of flow are often location dependent and the stationarity of flow is
violated. The nonstationarity of velocity field may originate from finite domain
boundaries, complex flow configurations (pumping and injecting), nonstationarity of
medium properties or conditioning of the log conductivity field to measurements of
head or conductivity. Moreover the lack of ergodicity related to the finite size of
solute sources makes difficult transport analyses that are often carried out by
rough schematizations. Some examples of solute dispersion of nonergodic passive
solute plume in heterogeneous formations with nonstationary flow conditions are here
considered and solved by a new approach. By this method the spatial moments of
finite initial volume of solute are obtained from the statistics of velocity field
evaluated by first-order perturbation expansion of steady state flow equation in
Taylor series combined with a finite element discretization. The approach allows to
handle nonstationarity due to several causes and is here applied to some test cases
in bounded domains. A comparison of numerical results in terms of particle
displacements moments with known solutions available in literature and with Monte
Carlo simulations gives a measure of the effect related to the lack of plume
ergodicity and of flow spatial stationarity in real-world transport analyses.