Modeling Dewatered Domains in Multilayer Analytic Element Models

Fitts, Charles R.

doi:10.1111/gwat.12645

Cited by 5 publications

(2 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Current methods for preventing or addressing problems with the drying and rewetting of grid cells in groundwater models can be summarized into two categories. The first has no physical mechanism and is more of a modeling technique, such as increasing the tolerance of the model convergence and lowering the bottom of key areas (Painter et al., 2008), adjusting the vertical discretization of the model (Keating & Zyvoloski, 2009; Markstrom et al., 2008), assigning minimal saturation thicknesses to dry cells (Doherty, 2001; Lin et al., 2010), converting the nearly dry unconfined domain into a confined domain to simulate (Fitts, 2018; Fitts et al., 2015), etc., which avoid the drying of the simulation domain. In some cases, this method can produce an acceptable simulation effect, but such nonphysical adjustments also raise concerns about the accuracy and reliability of the simulation results (Hunt & Feinstein, 2012; Painter et al., 2008).…”

Section: Introductionmentioning

confidence: 99%

Simulation of Drying‐Rewetting Processes in Numerical Groundwater Models Using a New Picard Iteration‐Based Method

Lu,

Sun

et al. 2024

Water Resources Research

View full text Add to dashboard Cite

When simulating groundwater flow in unconfined and convertible aquifers using a groundwater model with the block‐centered finite‐difference approach, such as MODFLOW, it frequently encounters drying and rewetting of cells. Although many drying and rewetting simulation methods have been proposed in the past, balancing simulation accuracy and convergence capability all at once is difficult. MODFLOW‐2005, which has second‐order accuracy, employs a trial‐and‐error method, but it suffers from computational instability when large quantities of grid cells are dried. MODFLOW‐NWT adopts the upstream‐weighting approach and Newton iteration method to ensure the stability of the drying and rewetting simulations. However, the upstream‐weighting approach has only first‐order accuracy, and the Newton iteration method is complex to implement because it necessitates the establishment of an additional Jacobian matrix. The methods employed by MODFLOW‐NWT are also available in MODFLOW 6, therefore it inherits both the strengths and weaknesses of MODFLOW‐NWT. In this study, a new method, Picard iteration‐based always active cell (PAAC), is proposed. Similar to MODFLOW‐NWT, the PAAC method also uses dry cells as active cells. The PAAC method, however, does not use the upstream‐weighting approach and has second‐order accuracy. Moreover, it ensures good convergence stability even under the Picard iteration method. In addition to discussing the algorithm, five cases were used to comprehensively compare the simulation effects of the PAAC method with MODFLOW‐2005 and MODFLOW‐NWT, including an analytical solution, repeated drying‐rewetting of multi‐layer grids, pumping well problem, perched aquifer problem and a nearly dry single‐layer grid, which verified the practicability of the PACC method.

show abstract

Section: Introductionmentioning

confidence: 99%

Simulation of Drying‐Rewetting Processes in Numerical Groundwater Models Using a New Picard Iteration‐Based Method

Lu,

Sun

et al. 2024

Water Resources Research

View full text Add to dashboard Cite

show abstract

“…Schenk et al () take a new look at the relationships between observations and model outputs. Fitts () illustrates how simulating problems like mine drainage using the analytic element method requires clever numerical techniques to approximate a moving water table as the domain dewaters. From a different application perspective, de Lange and Vink () illustrate the injection of a continuous resistance layer to decrease seepage over a defined area, such as required during construction.…”

mentioning

confidence: 99%