Simulation of hydrodynamics and nitrogen transformation processes in HSF constructed wetlands and porous media using the advection–dispersion-reaction equation with linear sink-source terms

2011 ◽  
Vol 37 (9) ◽  
pp. 1407-1415 ◽  
Author(s):  
Konstantinos N. Moutsopoulos ◽  
Valantis G. Poultsidis ◽  
John N.E. Papaspyros ◽  
Vassilios A. Tsihrintzis
Keyword(s):  
Porous Media ◽  
Constructed Wetlands ◽  
Nitrogen Transformation ◽  
Source Terms ◽  
Reaction Equation ◽  
Advection Dispersion ◽  
Transformation Processes

Assessment of groundwater contamination by chlorpyrifos using the PWC model in Valencia Region (Spain)

2021 ◽  
Author(s):  
Ricardo Pérez Indoval ◽  
Javier Rodrigo-Ilarri ◽  
Eduardo Cassiraga
Keyword(s):  
Reactive Transport ◽  
Management Practices ◽  
Fate And Transport ◽  
Environmental Modeling ◽  
Transport Processes ◽  
Negative Effects ◽  
Advection Dispersion ◽  
Agricultural Applications ◽  
Transformation Processes ◽  
Mass Transport Equation

<p>Chlorpyrifos is commoly used as an pesticide to control weeds and prevent nondesirable grow of algae, fungi and bacteria in many agricultural applications. Despite its highly negative effects on human health, environmental modeling of this kind of pesticide in the groundwater is not commonly done in real situations. Predicting the fate of pesticides released into the natural environment is necessary to anticipate and minimize adverse effects both at close and long distances from the contamination source. A number of models have been developed to predict the behavior, mobility, and persistence of pesticides. These models should account for key hydrological and agricultural processes, such as crop growth, pesticide application patterns, transformation processes and field management practices.</p><p>This work shows results obtained by the Pesticide Water Calculator (PWC) model to simulate the behavior of chlorpyrifos. PWC model is used as a standard pesticide simulation model in USA and in this work it has been used to  simulate the fate and transport of chlorpyrifos in the unsaturated zone of the aquifer. The model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. PWC is used to estimate the daily concentrations of chlorpyrifos in the Buñol-Cheste aquifer in Valencia Region(Spain).</p><p>A whole set of simulation scenarios have been designed to perform a parameter sensitivity analysis. Results of the PWC model obtained in this study represents a crucial first step towards the development of a pesticide risk assessment in Valencia Region. Results show that numerical simulation is a valid tool for the analysis and prediction of the fate  and transport of pesticides in the groundwater.</p>

Effects of wheat/faba bean intercropping on soil nitrogen transformation processes

2018 ◽  
Vol 19 (4) ◽  
pp. 1724-1734
Author(s):  
Yongbo Xu ◽  
Weiwen Qiu ◽  
Jianping Sun ◽  
Christoph Müller ◽  
Baokun Lei
Keyword(s):  
Soil Nitrogen ◽  
Faba Bean ◽  
Nitrogen Transformation ◽  
Transformation Processes

Simulation of thermal behavior of nanoparticles due to appearance of MHD

2021 ◽  
pp. 2150141
Author(s):  
Yahya Ali Rothan
Keyword(s):  
Porous Media ◽  
Thermal Behavior ◽  
Lorentz Force ◽  
Source Terms ◽  
Hybrid Nanomaterial ◽  
Accuracy Increase

To illustrate the role of Lorentz force on migration of nanopowders, CVFEM simulation has been reported in current research. The chamber contains hybrid nanomaterial and made up form porous media. Momentum equations have been modified for present paper with adding new source terms. The mentioned method works based on FEM in generation of mesh and calculation of gradient of scalars while it uses FVM approach for employing source terms. Testing with benchmark article shows the nice accuracy. Increase of permeability can enhance the speed of nanopowders and iso-temperature lines shapes become complicated. Impose of MHD creates new force against buoyancy and declines the velocity of the nanomaterial. Also, complication of isotherms declines with rise of Ha. With growth of Da, value of [Formula: see text] increases about 111% and 64.2% when [Formula: see text] and 20, respectively. Also, augment of Ha results in reduction of velocity about 30% and 47.6% when [Formula: see text] and 100. Given [Formula: see text], Nu for [Formula: see text] is 6.83 times bigger than case with [Formula: see text]. Nu decreases to about 67.28% with increase of Ha when [Formula: see text], [Formula: see text]. As Da increases, Nu rises about 62% when [Formula: see text], [Formula: see text].

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