We study numerically the tortuosity–porosity relation in a microscopic model of a porous medium arranged as a collectin of freely overlapping squares. It is demonstrated that the finite-size effects and the discretization errors, which were ignored in previous studies, may cause significant underestimation of tortuosity. The simple tortuosity calculation method proposed here eliminates the need...

2 Geomorphologist and Hydraulic Engineer, respectively, Water Engineering & Technology, Inc., Fort Collins, Colorado. Abstract: A 160km-long reach of Sacramento River was studied with the objective of predicting future changes in channel planform and their effects on water-surface elevations. Planform data were used to develop regression relationships between bend radius of curvature (Rc) and b...

Low-density lipoprotein (LDL) transport while incorporating the thickening of the arterial wall and cholesterol lipid accumulation is analyzed. A multi-layered model is adopted to represent the heterogeneity using the Darcy-Brinkman and Staverman filtration equations to describe transport within the porous layers of the wall. The fiber matrix model is utilized to represent the cholesterol lipid...

This computational study analyzes how to design a drainage system for porous scaffolds so that the scaffolds can be vascularized and perfused without collapse of the vessel lumens. We postulate that vascular transmural pressure--the difference between lumenal and interstitial pressures--must exceed a threshold value to avoid collapse. Model geometries consisted of hexagonal arrays of open chann...

The determination of permeability in heterogeneous and anisotropic reservoirs is a complex problem, because core samples and well test data are usually only available for limited number of wells. This paper presents hydraulic flow units and flow zone indicator for predicting permeability of rock mass from core and well log-data. The concept is applied to some uncored wells/intervals to predict ...

A procedure is presented for calculating the hydraulic conductivity of an aquifer near a well from the rate of rise of the water level in the well after a certain volume of water is suddenly removed. The calculation is based on the Thiem equation of steady state flow to a welL. The effective radius Re over which the head difference between the equilibrium water table in the aquifer and the wate...

Oscillatory well pumping was proposed recently as a tool for hydraulic tomography. Periodic pumping at a few frequencies is carried out through vertical intervals along the pumping well and the periodic head is measured along a few piezometers. The paper presents an analytical solution for the head field in an unconfined aquifer of finite depth under the common assumptions of a linearized water...

This study presents a semi-analytical solution for the problem of leakage in an unconfined aquifer bounded below by an aquitard of finite or semi-infinite extent. The homogeneous anisotropic unconfined aquifer of infinite radial extent is pumped continuously at a constant rate from a well of infinitesimal radius. The aquitard is also homogeneous , anisotropic and of infinite radial extent. Flow...

We study numerically the tortuosity-porosity relation in a microscopic model of a porous medium arranged as a collection of freely overlapping squares. It is demonstrated that the finite-size, slow relaxation and discretization errors, which were ignored in previous studies, may cause significant underestimation of tortuosity. The simple tortuosity calculation method proposed here eliminates th...

introduction: distal radius fractures are a common traumatic injury, particularly in the elderly population. in the present study we examined the effectiveness of ultrasound guidance in the reduction of distal radius fractures in adult patients presenting to emergency department (ed). methods: in this prospective case control study, eligible patients were adults older than 18 years who presente...