A convective-dispersive-adsorptive flow model for solute transport in soils. II. Evaluation of single and two-component adsorption models for phosphate movement in soils

Soil Research ◽  
1981 ◽  
Vol 19 (3) ◽  
pp. 287 ◽  
Author(s):  
LAG Aylmore ◽  
V Murali
Keyword(s):  
Experimental Data ◽  
Solute Transport ◽  
Computer Simulations ◽  
Full Range ◽  
Breakthrough Curves ◽  
Time Dependent ◽  
Adsorption Models ◽  
Adsorption And Desorption ◽  
Phosphate Ions ◽  
Component Models

Comparisons have been made between experimental breakthrough curves for phosphate ions in soil columns and computer simulations of solute transport based on a number of different adsorption models. These include single component linear and non-linear, instantaneous and dynamic adsorption models; as well as the model incorporating a combination of instantaneous and time-dependent components suggested in Part I. While certain portions of the complete breakthrough curves for phosphate could be reasonably approximated using simple one-component models, these generally failed badly to describe the shape and position of the experimental data over the complete range of the breakthrough curve. This was even more evident when both adsorption and desorption phases were considered. On the other hand, the model described in Part I combining instantaneous linear and a simultaneous time-dependent (dynamic) Freundlich-type adsorption components provided a good simulation of the experimental data over the full range of the breakthrough curves for both adsorption and desorption phases. Of particular significance is the ability of the model to handle successive experimental breakthrough curves with different amounts of residual adsorption. A method for 'normalizing' the solute transport equations to facilitate computer simulations is presented.

A convective-dispersive-adsorptive flow model for solute transport in soils. I. Model description and some simulations

Soil Research ◽  
1981 ◽  
Vol 19 (1) ◽  
pp. 23 ◽  
Author(s):  
V Murali ◽  
LAG Aylmore
Keyword(s):  
Solute Transport ◽  
Computer Simulations ◽  
Numerical Solutions ◽  
Breakthrough Curves ◽  
Retardation Factor ◽  
Intermittent Flow ◽  
Simultaneous Occurrence ◽  
Model Description ◽  
Phase Concentration ◽  
Adsorption Desorption

Solute transport predictions are usually based on mathematical (analytical and numerical) solutions of partial differential equations describing convective-dispersive-adsorptive flow and ion-soil interactions. In this paper computer simulations based on a numerical model of solute transport in soil columns have been used to illustrate the significance of flow dynamics and adsorption-desorption parameters in determining the shape and position of solute breakthrough curves. Approximating non-linear isotherms of the form S = KCM, where S is adsorption phase concentration, Cis solution phase concentration, and K and M are constants, by linear isotherms of the form S = KC + � where E is the intercept, to facilitate the use of analytical solutions. has been shown to result in significant errors when the retardation factor fails to account for the intercept � (when � is zero, the retardation factor equals 1 + �K/�, where � is the bulk density and � is water content). Using the dynamic form of Freundlich adsorption, the importance of non-linearity in the equilibrium isotherms is demonstrated. Computer simulations have also been used to demonstrate the extreme importance of intermittent flow, the simultaneous occurrence of adsorption dynamics, ionic fixation and hysteresis during instantaneous adsorption and desorption in determining the transport of solutes in soils.

scholarly journals Numerical and experimental study on solute transport through physical aquifer model

2021 ◽  
Author(s):  
Muskan Mayank ◽  
Pramod Kumar Sharma
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Solute Transport ◽  
Breakthrough Curves ◽  
Time Dependent ◽  
Environmental Concerns ◽  
Transport Parameters ◽  
Spatial Moments ◽  
Advection Dispersion ◽  
Simplifying Assumptions

Abstract Environmental concerns have drawn much research interest in solute transport through porous media. Thus, contaminants of groundwater permeate through pores in the ground, and adsorption attenuates the pollution concentration as the pollutants adhere to the solid surface. Mathematical models based on certain simplifying assumptions have been used to predict solute transport. The transport of solutes in porous media is governed by a partial differential equation known as the advection-dispersion equation. In this study, a two-dimensional numerical model has been developed for solute transport through porous media. Results of spatial moments have been predicted and analysed in the presence of both constant and time-dependent dispersion coefficients. Afterward, a numerical model is used to simulate experimentally observed breakthrough curves for both conservative and non-conservative solutes. Thus, transport parameters are estimated through numerical simulation of observed breakthrough curves. Finally, this model gives the best simulation of observed breakthrough curves, and it can also be used in the field scale.

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

scholarly journals Interpreting Locked Photographic Data: The Case of Apollo 17 Photo GPN-2000-00113

Designs ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Pyrrhon Amathes ◽  
Paul Christodoulides
Keyword(s):  
Experimental Data ◽  
Computer Simulations ◽  
The Moon ◽  
Geometrical Analysis ◽  
Apparent Position ◽  
Apollo Program ◽  
The Earth ◽  
Novel Approach ◽  
The World ◽  
The Moment

Photography can be used for pleasure and art but can also be used in many disciplines of science, because it captures the details of the moment and can serve as a proving tool due to the information it preserves. During the period of the Apollo program (1969 to 1972), the National Aeronautics and Space Administration (NASA) successfully landed humans on the Moon and showed hundreds of photos to the world presenting the travel and landings. This paper uses computer simulations and geometry to examine the authenticity of one such photo, namely Apollo 17 photo GPN-2000-00113. In addition, a novel approach is employed by creating an experimental scene to illustrate details and provide measurements. The crucial factors on which the geometrical analysis relies are locked in the photograph and are: (a) the apparent position of the Earth relative to the illustrated flag and (b) the point to which the shadow of the astronaut taking the photo reaches, in relation to the flagpole. The analysis and experimental data show geometrical and time mismatches, proving that the photo is a composite.

Biochar caged zirconium ferrite nanocomposites for the adsorptive removal of Reactive Blue 19 dye in a batch and column reactors and conditions optimizaton

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shazia Perveen ◽  
Raziya Nadeem ◽  
Shaukat Ali ◽  
Yasir Jamil
Keyword(s):  
Experimental Data ◽  
Low Dose ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Adsorption Efficiency ◽  
Fixed Bed Column ◽  
Flow Rates ◽  
Adsorptive Removal ◽  
Reactive Blue 19 ◽  
Pseudo Second Order

Abstract Biochar caged zirconium ferrite (BC-ZrFe2O5) nanocomposites were fabricated and their adsorption capacity for Reactive Blue 19 (RB19) dye was evaluated in a fixed-bed column and batch sorption mode. The adsorption of dye onto BC-ZrFe2O5 NCs followed pseudo-second-order kinetics (R 2 = 0.998) and among isotherms, the experimental data was best fitted to Sips model as compared to Freundlich and Langmuir isotherms models. The influence of flow-rate (3–5 mL min−1), inlet RB19 dye concentration (20–100 mg L−1) and quantity of BC-ZrFe2O5 NCs (0.5–1.5 g) on fixed-bed sorption was elucidated by Box-Behnken experimental design. The saturation times (C t /C o  = 0.95) and breakthrough (C t /C o  = 0.05) were higher at lower flow-rates and higher dose of BC-ZrFe2O5 NCs. The saturation times decreased, but breakthrough was increased with the initial RB19 dye concentration. The treated volume was higher at low sorbent dose and influent concentration. Fractional bed utilization (FBU) increased with RB19 dye concentration and flow rates at low dose of BC-ZrFe2O5 NCs. Yan model was fitted best to breakthrough curves data as compared to Bohart-Adams and Thomas models. Results revealed that BC-ZrFe2O5 nanocomposite has promising adsorption efficiency and could be used for the adsorption of dyes from textile effluents.

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

A Single Technically Consistent Design Formula for the Thickness of Cylindrical Sections Under Internal Pressure

2006 ◽  
Vol 129 (1) ◽  
pp. 211-215 ◽  
Author(s):  
John D. Fishburn
Keyword(s):  
Experimental Data ◽  
Internal Pressure ◽  
State Of The Art ◽  
Original Data ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Design Codes ◽  
Recent Developments ◽  
Current Design ◽  
Single Formula

Within the current design codes for boilers, piping, and pressure vessels, there are many different equations for the thickness of a cylindrical section under internal pressure. A reassessment of these various formulations, using the original data, is described together with more recent developments in the state of the art. A single formula, which can be demonstrated to retain the same design margin in both the time-dependent and time-independent regimes, is shown to give the best correlation with the experimental data and is proposed for consideration for inclusion in the design codes.

Sign in / Sign up

Export Citation Format

Share Document