Non-darcian flow in a fractured aquifer

Download

index.pdf

Date

2005

Author

Altınörs, Adnan Altay

Metadata

Show full item record

Item Usage Stats

180
views

76
downloads

Non-Darcian flow in a finite fractured aquifer is studied in this thesis. A stream bounds the aquifer at one side and an impervious stratum at the other. The aquifer consists of fractures capable of transmitting water rapidly and porous blocks which mainly store water. Unsteady flow in the aquifer due to a sudden or a gradual rise in the stream level is analysed by the double-porosity conceptual model. Governing equations for the flow in fractures and blocks are developed using the continuity equation. The fluid velocity in fractures is often too high for the linear Darcian flow so that the governing equation for fracture flow is modified by Forcheimer̕s equation which incorporates a nonlinear term. Governing equations are coupled by an interaction term that controls the quasi-steady state fracture-block interflow. Governing equations are solved numerically by the Crank-Nicolson implicit scheme. The numerical results are compared to the analytical results for the same problem which assumes Darcian flow both in fractures and blocks. Numerical and analytical solutions give same results when Reynold̕s number is less than 0.1. The effect of non-linearity on the flow appears when Reynold̕s number is greater than 0.1. The larger the piezometric head gradient, the higher the flow rate and, thus, higher the non-linearity is. The effect of aquifer parameters on the flow is also investigated. The proposed model and its numerical solution is a unique application of non-linear flow models to the fractured aquifers. It can be used in predicting water levels in fractured aquifers and evaluating time dependent flow rates in the analysis of recession hydrographs.

Subject Keywords

Hydraulic engineering.

URI

http://etd.lib.metu.edu.tr/upload/12606386/index.pdf
https://hdl.handle.net/11511/15801

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Solution of one-dimensional transient flow in fractured aquifers by numerical Laplace transform inversion Dündar, Serdar; Önder, Halil; Department of Civil Engineering (2005) Laplace transform step-response functions are presented for one dimensional transient flow in fractured semi-infinite & finite aquifers. Unsteady flow in the aquifer resulting from a constant discharge pumped from the stream is considered. Flow is one-dimensional, perpendicular to the stream in the confined aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width. The Laplace domain solutions are numerically inverted to the real-tim...
Determination of hydraulic parameters of semi-infinite aquifers using Marquardt algorithm Taşkan, Cüneyt; Önder, Halil; Department of Civil Engineering (2004) In this study, transmissivity and storage coefficient of a semi-infinite, confined, homogeneous and isotropic aquifer, where the flow is one-dimensional and linear, are determined using Marquardt algorithm, considering two independent cases: constant drawdown in the adjacent stream; or constant discharge from the aquifer due to pumping at a constant rate. In the first case piezometric head and discharge measurements are utilized. Hydraulic diffusivity, which is the ratio of transmissivity to storage coeffic...
Forced hydraulic jump on artificially roughened beds Şimşek, Çağdaş; Tokyay, Nuray; Department of Civil Engineering (2006) In the scope of the study, prismatic roughness elements with different longitudinal spacing and arrangements have been tested in a rectangular flume in order to reveal their effects on fundamental characteristics of a hydraulic jump. Two basic roughness types with altering arrangements have been tested. Roughness elements of the first type extends through the channel width against the flow with varying length and pitch ratios for different arrangements. The second type is of staggered essence and produced b...
Solution of one dimensional transient flow in composite aquifers using stehfest algorithm Bakar, Ürün; Önder, Halil; Department of Civil Engineering (2010) In this study, piezometric heads in a composite aquifer composed of an alluvial deposit having a width adjacent to a semi-infinite fractured rock are determined. One dimensional transient flow induced by a constant discharge pumping rate from a stream intersecting alluvial part of the aquifer is considered. Parts of the aquifer are homogeneous andisotropic. Equations of flow, initial and boundary conditions are converted to dimensionless forms for graphical presentation and the interpretation of results ind...
Investigation of waterhammer problems in the penstocks of small hydropower plants Çalamak, Melih; Bozkuş, Zafer; Department of Civil Engineering (2010) Waterhammer is an unsteady hydraulic problem which is commonly found in closed conduits of hydropower plants, water distribution networks and liquid pipeline systems. Due to either a malfunction of the system or inadequate operation conditions, pipeline may collapse or burst erratically resulting in substantial damages, and human losses in some cases. In this thesis, time dependent flow situations in the penstocks of small hydropower plants are investigated. A software, HAMMER, that utilizes method of chara...

Citation Formats

A. A. Altınörs, “Non-darcian flow in a fractured aquifer,” Ph.D. - Doctoral Program, Middle East Technical University, 2005.