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Improving sub-grid scale accuracy of boundary features in regional finite-difference models

May 25, 2012

As an alternative to grid refinement, the concept of a ghost node, which was developed for nested grid applications, has been extended towards improving sub-grid scale accuracy of flow to conduits, wells, rivers or other boundary features that interact with a finite-difference groundwater flow model. The formulation is presented for correcting the regular finite-difference groundwater flow equations for confined and unconfined cases, with or without Newton Raphson linearization of the nonlinearities, to include the Ghost Node Correction (GNC) for location displacement. The correction may be applied on the right-hand side vector for a symmetric finite-difference Picard implementation, or on the left-hand side matrix for an implicit but asymmetric implementation. The finite-difference matrix connectivity structure may be maintained for an implicit implementation by only selecting contributing nodes that are a part of the finite-difference connectivity. Proof of concept example problems are provided to demonstrate the improved accuracy that may be achieved through sub-grid scale corrections using the GNC schemes.

Publication Year 2012
Title Improving sub-grid scale accuracy of boundary features in regional finite-difference models
DOI 10.1016/j.advwatres.2012.02.011
Authors Sorab Panday, Christian D. Langevin
Publication Type Article
Publication Subtype Journal Article
Series Title Advances in Water Resources
Index ID 70009651
Record Source USGS Publications Warehouse
USGS Organization Office of Groundwater