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Groundwater
Published in Sandeep Samantaray, Abinash Sahoo, Dillip K. Ghose, Watershed Management and Applications of AI, 2021
Sandeep Samantaray, Abinash Sahoo, Dillip K. Ghose
A French hydraulic engineer Henry Darcy in 1856 studied the flow of water through horizontal beds of sand to be utilized for filtration of water. He attempted to determine the law of flow of water through filters by precise experiments. These experiments positively demonstrate that the volume of water passing through a sand bed of a given nature is directly proportional to pressure whereas inversely proportional to thickness of traversed bed; thus, in calling the surface area of a filter, k – coefficient based on nature of sand, e – thickness of sand bed, P-Ho pressure below the filtering bed, P+H – pressure of atmosphere summed with water depth on filter. Universally, Darcy's law can be defined as the flow rate through porous media which is proportional to head loss and is inversely proportional to length of flow path. More than any other contribution, it assists as the base for present-day information regarding flow of groundwater. Study and explanation of difficulties related to movement of groundwater and well hydraulics started only after Darcy's experimental study.
Introduction
Published in Yu. K. Tovbin, The Molecular Theory of Adsorption in Porous Solids, 2017
where [K] denotes the permeability, not to be confused with the formulas (3.8). Here permeability is the dimension of the area; it does not depend on the fluid properties and is a purely geometric characteristic of the porous medium. The unit of measurement of permeability is darcy (1 darcy = 1.02 ⋅ 10−8cm2) . From dimensional analysis it follows that [K] = f(Fp, …) , ξ2, where f(Fp, …) —the dimensional function of dimensionless parameters of the porous structure, in particular the porosity, ξ —pore size.
Sedimentary Texture
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
Permeability is the property allowing passage of fluid through a rock. The unit of permeability is a darcy. According to the American Petroleum Institute, a porous medium is said to have a permeability of one darcy ‘when a single phase fluid of one centipoise viscosity that completely fills the voids of the medium will flow through it under conditions of viscous flow at a rate of one centimeter per second per square centimeter of cross-sectional area under a pressure of equivalent hydraulic gradient of one atmosphere (76.0 cm of Hg) per centimeter’.
Assessment Techniques for Studying the Effects of Fire on Stone Materials: A Literature Review
Published in International Journal of Architectural Heritage, 2020
Edite Martinho, Amélia Dionísio
A ‘Darcy unit’, or darcy, is thus defined as ‘the permeability of a material which permits a volume flow density of 1 cm.s−1 of a fluid of 1 cP (centipoises of viscosity) under a pressure gradient of 1 atm.cm−1ʹ. Stone permeability values can vary from 1 darcy to 1 nanodarcy or even less (Guéguen, Gavrilenko, and Le Ravalec 1996). Permeability is usually determined for different fluids such as inert gases (e.g. air, nitrogen), water and also water vapour. When inert gas is used as the permeating fluid, it reflects stone permeability under ideal conditions. However, if the percolating fluid is reactive to stone, other factors such as the wettability of the fluid, the swelling of clays and other minerals and the chemical interaction between rock and fluid will affect permeability (Chaki, Takarli, and Agbodjan 2008).
Optimal duct layout for HVAC using topology optimization
Published in Science and Technology for the Built Environment, 2018
Mark Christian E. Manuel, Po Ting Lin, Ming Chang
Fluid topology optimization strategies have already been introduced and applied to fluid flow assuming Stokes flow (Borrvall and Petersson 2003; i.e., steady friction dominated flow where inertia is neglected). The same authors extended the methodology to Darcy–Stokes flows (Wiker et al. 2007) where the free flow regions are described by Stokes' equations, and the porous flow by Darcy's equation. These studies had probably introduced the most commonly varied parameter being used in fluid topology today. The porosity of each discretized element in the design domain is varied through a penalty function for the Darcy's Law. Darcy's Law is a derived constitutive equation that describes the flow of a fluid through a porous medium. More recently, extensions to Navier–Stokes flows (Dede et al. 2014; Gersborg-Hansen et al. 2005) and non-Newtonian flows (Pingen and Maute 2010) were investigated. The governing equation for steady state Navier–Stokes laminar fluid flow in the absence of body forces with the introduction of the variable parameter is given as:
State of the art on the hydraulic properties of pervious concrete
Published in Road Materials and Pavement Design, 2023
Khaled Seifeddine, Sofiane Amziane, Evelyne Toussaint
Darcy's law is a physical law that expresses the flow rate of an incompressible fluid filtering through a porous medium. The flow of this fluid between two points is determined by the hydraulic conductivity or the permeability coefficient of the substrate and by the pressure gradient of the fluid. Darcy's law expresses the flow rate of an incompressible fluid flowing in the steady state through a porous medium of sectional area and length due to a difference in charge (Equation (6)). The constant-head permeability test is recommended by ACI (Yang et al., 2020); this test measures the quantity of water passing through a sample in a specified time (s). A schematic view of this test is presented in Figure 1. Note the sample of pervious concrete, with an area and height of (cm2) and (cm), respectively; the volume of water through the sample (cm3); and (cm), which corresponds to the sum of the heights of the sample and the water column. The permeability measured with a constant-head permeameter (cm/s) is calculated by Equation (7) (Cai et al., 2021).