FEFLOW

FEFLOW
Original author(s)	Hans-Jörg G. Diersch
Developer(s)	DHI Group
Operating system	Linux, Microsoft Windows
Type	FEM software
License	proprietary
Website	www.feflow.com

Last updated August 08, 2019

FEFLOW (Finite Element subsurface FLOW system) is a computer program for simulating groundwater flow, mass transfer and heat transfer in porous media and fractured media. The program uses finite element analysis to solve the groundwater flow equation of both saturated and unsaturated conditions as well as mass and heat transport, including fluid density effects and chemical kinetics for multi-component reaction systems.

Computer simulation is the reproduction of the behavior of a system using a computer to simulate the outcomes of a mathematical model associated with said system. Since they allow to check the reliability of chosen mathematical models, computer simulations have become a useful tool for the mathematical modeling of many natural systems in physics, astrophysics, climatology, chemistry, biology and manufacturing, human systems in economics, psychology, social science, health care and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology and to estimate the performance of systems too complex for analytical solutions.

Groundwater water located beneath the ground surface

Groundwater is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics and hydrodynamics. Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation,

History

The software was firstly introduced by Hans-Jörg G. Diersch in 1979, see and.[1] He developed the software in the Institute of Mechanics of the German Academy of Sciences Berlin up to 1990. In 1990 he was one of the founders of WASY GmbH of Berlin, Germany (the acronym WASY translates from German to Institute for Water Resources Planning and Systems Research), where FEFLOW has been developed further, continuously improved and extended as a commercial simulation package. In 2007 the shares of WASY GmbH were purchased by DHI. The WASY company has been fused and FEFLOW became part of the DHI Group software portfolio. FEFLOW is being further developed at DHI by an international team. Software distribution and services are worldwide.

Berlin is the capital and largest city of Germany by both area and population. Its 3,748,148 (2018) inhabitants make it the second most populous city proper of the European Union after London. The city is one of Germany's 16 federal states. It is surrounded by the state of Brandenburg, and contiguous with its capital, Potsdam. The two cities are at the center of the Berlin-Brandenburg capital region, which is, with about six million inhabitants and an area of more than 30,000 km², Germany's third-largest metropolitan region after the Rhine-Ruhr and Rhine-Main regions.

Germany, officially the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north and the Alps, Lake Constance and the High Rhine to the south. It borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, France to the southwest, and Luxembourg, Belgium and the Netherlands to the west.

DHI, previously known as DHI - Institut for Vand og Miljø, is an international software development and engineering consultant firm headquartered in Denmark which specializes in hydraulic and hydrological modeling software. Originating in an institute founded in 1964, DHI has about 30 offices throughout the world, with software development centres in Singapore and Hørsholm, Denmark, and approximately 1100 employees.

Technology

The program is offered in both 32-bit and 64-bit versions for Microsoft Windows and Linux operating systems.

In computer architecture, 32-bit integers, memory addresses, or other data units are those that are 32 bits wide. Also, 32-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size. 32-bit microcomputers are computers in which 32-bit microprocessors are the norm.

Microsoft Windows is a group of several graphical operating system families, all of which are developed, marketed and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Microsoft Windows families include Windows NT and Windows IoT; these may encompass subfamilies, e.g. Windows Server or Windows Embedded Compact. Defunct Microsoft Windows families include Windows 9x, Windows Mobile and Windows Phone.

Linux Family of free and open-source software operating systems based on the Linux kernel

Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution.

FEFLOW's theoretical basis is fully described in the comprehensive FEFLOW book.^[1] It covers a wide range of physical and computational issues in the field of porous/fractured-media modeling. The book starts with a more general theory for all relevant flow and transport phenomena on the basis of the continuum mechanics, systematically develops the basic framework for important classes of problems (e.g., multiphase/multispecies non-isothermal flow and transport phenomena, variably saturated porous media, free-surface groundwater flow, aquifer-averaged equations, discrete feature elements), introduces finite element methods for solving the basic multidimensional balance equations, in detail discusses advanced numerical algorithms for the resulting nonlinear and linear problems, and completes with a number of benchmarks, applications and exercises to illustrate the different types of flow, mass and heat transport problems (e.g., subsurface flow and seepage problems, unsaturated-saturated flow, advective-diffusion transport, saltwater intrusion, geothermal and thermohaline flow).

Continuum mechanics is a branch of mechanics that deals with the mechanical behavior of materials modeled as a continuous mass rather than as discrete particles. The French mathematician Augustin-Louis Cauchy was the first to formulate such models in the 19th century.

In hydrogeology, groundwater flow is defined as the "...part of streamflow that has infiltrated the ground, has entered the phreatic zone, and has been discharged into a stream channel, or springs and seepage water." It is governed by the groundwater flow equation. Groundwater is water that is found underground in cracks and spaces in the soil, sand and rocks. An area where water fills these spaces is called a phreatic zone or saturated zone. Groundwater is stored in and moves slowly through the layers of soil, sand and rocks called aquifers. The rate of groundwater flow depends on the permeability and the hydraulic head.

In computing, a benchmark is the act of running a computer program, a set of programs, or other operations, in order to assess the relative performance of an object, normally by running a number of standard tests and trials against it. The term benchmark is also commonly utilized for the purposes of elaborately designed benchmarking programs themselves.

Other groundwater simulators

MODFLOW
Groundwater Modeling System
MARTHE
HydroGeoSphere
HYDRUS
PORFLOW
MicroFEM LT
OpenGeoSys
Leapfrog Hydro
ECLIPSE simulator with the H2O extension

MODFLOW is the U.S. Geological Survey modular finite-difference flow model, which is a computer code that solves the groundwater flow equation. The program is used by hydrogeologists to simulate the flow of groundwater through aquifers. The source code is free public domain software, written primarily in Fortran, and can compile and run on Microsoft Windows or Unix-like operating systems.

HydroGeoSphere (HGS) is a 3D control-volume finite element groundwater model, and is based on a rigorous conceptualization of the hydrologic system consisting of surface and subsurface flow regimes. The model is designed to take into account all key components of the hydrologic cycle. For each time step, the model solves surface and subsurface flow, solute and energy transport equations simultaneously, and provides a complete water and solute balance.

Peer review

Trefry, M.G.; Muffels, C. (2007). "FEFLOW: a finite-element ground water flow and transport modeling tool". Ground Water. 45 (5): 525–528. doi:10.1111/j.1745-6584.2007.00358.x.

In computing, a digital object identifier (DOI) is a persistent identifier or handle used to identify objects uniquely, standardized by the International Organization for Standardization (ISO). An implementation of the Handle System, DOIs are in wide use mainly to identify academic, professional, and government information, such as journal articles, research reports and data sets, and official publications though they also have been used to identify other types of information resources, such as commercial videos.

Related Research Articles

An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials. Groundwater can be extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer. If the impermeable area overlies the aquifer, pressure could cause it to become a confined aquifer.

The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water.

Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust. The terms groundwater hydrology, geohydrology, and hydrogeology are often used interchangeably.

Darcy's law is an equation that describes the flow of a fluid through a porous medium. The law was formulated by Henry Darcy based on results of experiments on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of earth sciences.

Used in hydrogeology, the groundwater flow equation is the mathematical relationship which is used to describe the flow of groundwater through an aquifer. The transient flow of groundwater is described by a form of the diffusion equation, similar to that used in heat transfer to describe the flow of heat in a solid. The steady-state flow of groundwater is described by a form of the Laplace equation, which is a form of potential flow and has analogs in numerous fields.

Groundwater models are computer models of groundwater flow systems, and are used by hydrogeologists. Groundwater models are used to simulate and predict aquifer conditions.

Hydrus (software) hydrologic simulation software suite

Hydrus is a suite of Windows-based modeling software that can be used for analysis of water flow, heat and solute transport in variably saturated porous media. HYDRUS suite of software is supported by an interactive graphics-based interface for data-preprocessing, discretization of the soil profile, and graphic presentation of the results. While HYDRUS-1D simulates water flow, solute and heat transport in one-dimension, and is a public domain software, HYDRUS 2D/3D extends the simulation capabilities to the second and third dimensions, and is distributed commercially.

MIKE SHE is an integrated hydrological modelling system for building and simulating surface water flow and groundwater flow. MIKE SHE can simulate the entire land phase of the hydrologic cycle and allows components to be used independently and customized to local needs. MIKE SHE emerged from Système Hydrologique Européen (SHE) as developed and extensively applied since 1977 onwards by a consortium of three European organizations: the Institute of Hydrology, SOGREAH (France) and DHI (Denmark). Since then, DHI has continuously invested resources into research and development of MIKE SHE. MIKE SHE can be used for the analysis, planning and management of a wide range of water resources and environmental problems related to surface water and groundwater, especially surface-water impact from groundwater withdrawal, conjunctive use of groundwater and surface water, wetland management and restoration, river basin management and planning, impact studies for changes in land use and climate.

A hydrologic model is a simplification of a real-world system that aids in understanding, predicting, and managing water resources. Both the flow and quality of water are commonly studied using hydrologic models.

FEHM is a groundwater model that has been developed in the Earth and Environmental Sciences Division at Los Alamos National Laboratory over the past 30 years. The executable is available free at the FEHM Website. The capabilities of the code have expanded over the years to include multiphase flow of heat and mass with air, water, and CO₂, methane hydrate, plus multi-component reactive chemistry and both thermal and mechanical stress. Applications of this code include simulations of: flow and transport in basin scale groundwater systems , migration of environmental isotopes in the vadose zone, geologic carbon sequestration, oil shale extraction, geothermal energy, migration of both nuclear and chemical contaminants, methane hydrate formation, seafloor hydrothermal circulation, and formation of karst. The simulator has been used to generate results for more than 100 peer reviewed publications which can be found at FEHM Publications.

SVFLUX is a finite element seepage analysis program developed by SoilVision Systems Ltd.. The software is designed to analyze both saturated and unsaturated flow through the ground through the solving of Richard's equation. The program is used in the fields of civil engineering and hydrology in order to analyze seepage and groundwater regional flow. The software is used for the calculation of flow rates, pore-water pressures, and pumping rates associated with regional groundwater flow. The software can be coupled with CHEMFLUX in order to calculate diffusion, advection, and decay rates or with SVHEAT in order to calculate thermal gradients and freeze/thaw fronts.

SHETRAN is a hydrological modelling system for water flow, solute and sediment transport in river catchments. SHETRAN is a physically based, distributed model (PBDM) that can simulate the entire land phase of the hydrologic cycle including surface water flow and groundwater flow. The plan area of the catchment in SHETRAN is usually in the range of one to a few thousand square kilometres and the horizontal depth of the subsurface is usually less than 100m.

Reactive transport modeling in porous media refers to the creation of computer models integrating chemical reaction with transport of fluids through the Earth's crust. Such models predict the distribution in space and time of the chemical reactions that occur along a flowpath. Reactive transport modeling in general can refer to many other processes, including reactive flow of chemicals through tanks, reactors, or membranes; particles and species in the atmosphere; gases exiting a smokestack; and migrating magma.

MOOSE is an object-oriented C++ finite element framework for the development of tightly coupled multiphysics solvers from Idaho National Laboratory. MOOSE makes use of the PETSc non-linear solver package and libmesh to provide the finite element discretization.

The finite water-content vadose zone flux method represents a one-dimensional alternative to the numerical solution of Richards' equation for simulating the movement of water in unsaturated soils. The finite water-content method is an ordinary differential equation alternative to the Richards partial differential equation. The Richards equation is difficult to approximate in general because it does not have a closed-form analytical solution except in a few cases. The finite water-content method, is perhaps the first generic replacement for the numerical solution of the Richards' equation. The finite water-content solution has several advantages over the Richards equation solution. First, as an ordinary differential equation it is explicit, guaranteed to converge and computationally inexpensive to solve. Second, using a finite volume solution methodology it is guaranteed to conserve mass. The finite water content method readily simulates sharp wetting fronts, something that the Richards solution struggles with. The main limiting assumption required to use the finite water-content method is that the soil be homogeneous in layers.

The Marine Unsaturated Model is a two-dimensional finite element model capable of simulating the migration of water and solutes in saturated-unsaturated porous media while accounting for the impact of solute concentration on water density and viscosity, as saltwater is heaving and more viscous than freshwater. The detailed formulation of the MARUN model is found in and. The model was used to investigate seepage flow in trenches and dams, the migration of brine following evaporation and, submarine groundwater discharge, and beach hydrodynamics to explain the persistence of some of the Exxon Valdez oil in Alaska beaches.

In geology, numerical modeling is a widely applied technique to tackle complex geological problems by computational simulation of geological scenarios.

Noam Weisbrod is a Professor of Hydrology in the Department of Environmental Hydrology and Microbiology at the Zuckerberg Institute for Water Research (ZIWR), which is part of the Jacob Blaustein Institutes for Desert Research (BIDR) at Ben-Gurion University of the Negev (BGU). Weisbrod served as director of ZIWR from 2015 to 2018. In 2018 he became director of BIDR.

References

1 2 Diersch, Hans-Jörg G., FEFLOW – Finite element modeling of flow, mass and heat transport in porous and fractured media, Springer, 2014, Berlin Heidelberg, XXXV, 996p., ISBN 978-3-642-38738-8, ISBN 978-3-642-38739-5 (eBook), doi:10.1007/978-3-642-38739-5.

External links

Official website

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[Diersch-1] 1 2 Diersch, Hans-Jörg G., FEFLOW – Finite element modeling of flow, mass and heat transport in porous and fractured media, Springer, 2014, Berlin Heidelberg, XXXV, 996p., ISBN 978-3-642-38738-8, ISBN 978-3-642-38739-5 (eBook), doi:10.1007/978-3-642-38739-5.