scholarly journals Barrier effect of underground structures on aquifers

2021 ◽  
Author(s):  
Estanislao Pujades
Keyword(s):  
Head Loss ◽  
Empirical Equations ◽  
Barrier Effect ◽  
Underground Structures ◽  
Construction Sites ◽  
Natural Conditions ◽  
Barrier Effects ◽  
Head Gradient ◽  
Semi Empirical ◽  
Numerical And Analytical Methods

Impervious structures below the water table modify the natural groundwater flow in aquifers. They act as barriers, causing heads to rise upgradient and to fall downgradient. We define the barrier effect as the increase in head loss across the barrier with respect to the natural conditions prior to construction. We distinguish between regional (the minimum head loss observed at long distances) and local (the maximum head loss observed close to the structure) barrier effects. We use numerical and analytical methods to derive semi-empirical equations to quantify the two barrier effects for semi-permeable, partially penetrating (or fully penetrating but finite in length), and barriers with a by-pass in confined aquifers. The resulting equations depend on the barrier geometry and on the natural head gradient in the aquifer and they are easy to apply. We test their validity at two construction sites, obtaining excellent agreement between the computed and observed barrier effects.

scholarly journals Reaeration and oxygen dissipation into a circular hydraulic channel: experimental and dimensionless approach

RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Felipe Keiji Feital Harano ◽  
Murilo de Souza Ferreira ◽  
Marcos Vinícius Mateus ◽  
Deusmaque Carneiro Ferreira ◽  
Julio Cesar de Souza Inácio Gonçalves
Keyword(s):  
Interfacial Phenomena ◽  
Linear Regression Method ◽  
Hydraulic Parameters ◽  
Empirical Equations ◽  
Hydraulic Conditions ◽  
Do Concentration ◽  
Hydraulic Channel ◽  
M Estimates ◽  
Semi Empirical ◽  
Key Parameter

ABSTRACT Dissolved oxygen (DO) is a key parameter in water quality. The DO concentration in a water body can be changed by interfacial phenomena such as reaeration and oxygen dissipation, which can be represented by the coefficients K2 and KD, respectively. Few studies have jointly correlated K2 and KD with physical and hydraulic parameters of the channel. The present work investigated the behavior of these coefficients over a range of hydraulic conditions, and developed semi-empirical equations capable of relating both coefficients. Reaeration and DO dissipation tests were conducted in a circular hydraulic channel with flow velocity ranging from 0.20 to 0.79 m.s-1 and depth ranging from 0.09 to 0.15 m. Estimates of K2 and KD were performed using the non-linear regression method. Semi-empirical equations were obtained based on classical dimensional analysis and multiple regression analysis. The comparison between measured and estimated coefficients yielded R2 for reaeration and dissipation of 0.940 and 0.844, respectively. KD was higher than K2 for all turbulence levels applied at the hydraulic channel. An estimate obtained by the relation between the semi-empirical equations indicates that the transfer of oxygen in the water-air direction (dissipation) is approximately twice as fast as the transfer in the air-water direction (reaeration).

Development of a Mathematical Model for Performance Prediction of Planing Catamaran in Calm Water

2019 ◽  
Vol 161 (A2) ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Performance Prediction ◽  
Data Evaluation ◽  
Empirical Equations ◽  
Calm Water ◽  
Semi Empirical ◽  
The Mathematical Model ◽  
Comparison With Experimental Data

In this paper, an attempt has been made to predict the performance of a planing catamaran using a mathematical model. Catamarans subjected to a common hydrodynamic lift, have an extra lift between the two asymmetric half bodies. In order to develop a mathematical model for performance prediction of planing catamarans, existing formulas for hydrodynamic lift calculation must be modified. Existing empirical and semi-empirical equations in the literature have been implemented and compared against available experimental data. Evaluation of lift in comparison with experimental data has been documented. Parameters influencing the interaction between demi-hulls and separation effects have been analyzed. The mathematical model for planing catamarans has been developed based on Savitsky’s method and results have been compared against experimental data. Finally, the effects of variation in hull geometry such as deadrise angle and distance between two half bodies on equilibrium trim angle, resistance and wetted surface have been examined.

Mathematical Modeling of Drying Kinetics of Salted Otolithes Ruber at the Different Temperature

2013 ◽  
Vol 781-784 ◽  
pp. 1347-1352 ◽  
Author(s):  
Yan Yan Wu ◽  
Zhong Yang Ren ◽  
Lai Hao Li ◽  
Xian Qing Yang ◽  
Wan Ling Lin ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Experimental Data ◽  
Suitable Model ◽  
Empirical Equations ◽  
Thin Layer Drying ◽  
Electric Oven ◽  
Otolithes Ruber ◽  
Predicted Values ◽  
Semi Empirical ◽  
Kinetics Of

Salted Otolithes ruber with 80 (±5) g weight on dry basis were dried in the blast electric oven using different temperature (20, 30, 40 and 50°C) until the humidity fell down to 0.6 from 1.23 on dry basis. Drying processes were completed between 20-48h. In this study, experiment values were compared with predicted values obtained from twenty thin layer drying theoretical/ semi-empirical/ empirical equations. Models whose coefficient of correlation (R2) values are highest were chosen to be the best models. According to this, Midillis Model was defined as the most suitable model in which predicted value is closest to experimental data for 20°C level, Weibulls model was for 30°C level, Weibull distributions model was for 40°C level and Alibas model was for 50°C level.

Prediction of Water Wave Breaking Height and Depth Using ANFIS

2011 ◽  
Author(s):  
Ehsan Delavari ◽  
Ahmad Reza Mostafa Gharabaghi ◽  
Mohammad Reza Chenaghlou
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Fuzzy Inference System ◽  
Wave Breaking ◽  
Fuzzy Inference ◽  
Breaking Point ◽  
Empirical Equations ◽  
Anfis Model ◽  
Inference System ◽  
Semi Empirical

Wave height as well as water depth at the breaking point are two basic parameters which are necessary for studying coastal processes. In this paper, the application of Fuzzy Inference System (FIS) and Adaptive Neuro-Fuzzy Inference System (ANFIS) and semi-empirical models are investigated. The data sets used in this study are published laboratory data obtained from regular wave breaking on plane, impermeable slopes collected from 22 sources. Results indicate that the developed ANFIS model provides more accurate and reliable estimation of breaking wave height, compared to semi-empirical equations. However, some of semi-empirical equations provide better predictions of water depth at the breaking point compared to the ANFIS model.

Generalized Analytical Equation for the Top Heat Loss Factor of a Flat-Plate Solar Collector With N Glass Covers

1994 ◽  
Vol 116 (1) ◽  
pp. 43-46 ◽  
Author(s):  
S. K. Samdarshi ◽  
S. C. Mullick
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Loss Factor ◽  
Analytical Equation ◽  
Empirical Equations ◽  
Additional Advantage ◽  
Computational Errors ◽  
Flat Plate Solar Collector ◽  
Flat Plate Collector ◽  
Semi Empirical

A generalized analytical equation for the top heat loss factor of a flat-plate collector with one or more glass covers has been developed. The maximum computational errors resulting from the use of the analytical equation with several simplifications are ± 5 percent compared to numerical solution of the set of heat balance equations. The analytical equation is considerably more accurate than the available semi-empirical equations over the entire range of variables covered. An additional advantage of the proposed technique over the semi-empirical equations is that results can be obtained for different values of sky temperature, using any given correlation for convective heat transfer in the air gap spacings, and for any given values of fluid (air in the present case) properties.

Determination of Suction Forces and Moment on Parallel Manoeuvring Vessels for a Future Control System

2011 ◽  
Vol 180 ◽  
pp. 281-287 ◽  
Author(s):  
Witold Gierusz ◽  
Anna Waszkiel
Keyword(s):  
Control System ◽  
Pressure Distribution ◽  
Working Conditions ◽  
Empirical Equations ◽  
Cfd Simulations ◽  
Passenger Car ◽  
Computer Based ◽  
Semi Empirical

Vessels moving on parallel courses on the border of two mediums interact together. Ship to ship interactions are caused by irregular pressure distribution around the hull. Higher velocity of the fluid between hulls causes formation of the decreased pressure amidships. This is the base of suction forces and moments generation. Analytical computations and computer based CFD simulations were carried out on the basis of 3DOF models of two training ships - VLCC and Passenger Car Ferry. The results of both methods are comparable. Therefore the analytical semi-empirical equations can be implemented in a future control system, which requires ship to ship interactions estimations to ensure proper working conditions.

scholarly journals Barrier effect of underground structures on aquifers

2012 ◽  
Vol 145-146 ◽  
pp. 41-49 ◽  
Author(s):  
Estanislao Pujades ◽  
Ander López ◽  
Jesus Carrera ◽  
Enric Vázquez-Suñé ◽  
Anna Jurado
Keyword(s):  
Barrier Effect ◽  
Underground Structures
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