A multiple species transport model with sequential decay chain interactions in heterogeneous subsurface environments

1993 ◽  
Vol 29 (8) ◽  
pp. 2737-2746 ◽  
Author(s):  
W. W. McNab ◽  
T. N. Narasimhan
Keyword(s):  
Transport Model ◽  
Decay Chain ◽  
Species Transport ◽  
Sequential Decay ◽  
Subsurface Environments ◽  
Multiple Species

scholarly journals A tropospheric chemistry reanalysis for the years 2005–2012 based on an assimilation of OMI, MLS, TES and MOPITT satellite data

2015 ◽  
Vol 15 (6) ◽  
pp. 8687-8770
Author(s):  
K. Miyazaki ◽  
H. J. Eskes ◽  
K. Sudo
Keyword(s):  
Transport Model ◽  
Lower Troposphere ◽  
Tropospheric Chemistry ◽  
Atmospheric Environment ◽  
Data Sets ◽  
Chemical Transport Model ◽  
Observational Estimate ◽  
Multiple Species ◽  
Chemical Fields

Abstract. We present the results from an eight-year tropospheric chemistry reanalysis for the period 2005–2012 obtained by assimilating multiple retrieval data sets from the OMI, MLS, TES, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model and an ensemble Kalman filter technique that simultaneously optimises the chemical concentrations of various species and emissions of several precursors. The optimisation of both the concentration and the emission fields is an efficient method to correct the entire tropospheric profile and its year-to-year variations, and to adjust various tracers chemically linked to the species assimilated. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the analysed O3, NO2, and CO concentrations on regional and global scales and for both seasonal and year-to-year variations from the lower troposphere to the lower stratosphere. The data assimilation statistics imply persistent reduction of model error and improved representation of emission variability, but also show that discontinuities in the availability of the measurements lead to a degradation of the reanalysis. The decrease in the number of assimilated measurements increased the ozonesonde minus analysis difference after 2010 and caused spurious variations in the estimated emissions. The Northern/Southern Hemisphere OH ratio was modified considerably due to the multiple species assimilation and became closer to an observational estimate, which played an important role in propagating observational information among various chemical fields and affected the emission estimates. The consistent concentration and emission products provide unique information on year-to-year variations of the atmospheric environment.

Numerical Simulation of Two-Phase Liquid–liquid Flow in a New Static Mixer Structure

2011 ◽  
Vol 368-373 ◽  
pp. 1604-1607
Author(s):  
Hong Yan Zhang ◽  
Hai Hong Dong
Keyword(s):  
Numerical Simulation ◽  
Liquid Flow ◽  
Transport Model ◽  
Simulation Method ◽  
Static Mixer ◽  
Mixing Process ◽  
Two Phase ◽  
Species Transport ◽  
Mixing Effect ◽  
Phase Liquid

In this article, Spiral belt static mixer with changing diameter was taken as the object. The numerical simulation method was used to investigate the mixing process of two-phase liquid–liquid flow in water treatment by a commercial CFD code,namely Fluent.The k-ε model and species transport model were established to research this project. Then the mixing effect was compared with that of HEV static mixer. The result showed that spiral belt static mixer with changing diameter promote the mixing effect greatly. The mixing effect relative to that of HEV static mixer increased 10 times and the the pressure loss only increased 3 times.

Modelling species fate and porous media effects for landfill leachate flow

2005 ◽  
Vol 42 (4) ◽  
pp. 1116-1132 ◽  
Author(s):  
A J Cooke ◽  
R K Rowe ◽  
B E Rittmann
Keyword(s):  
Porous Media ◽  
Landfill Leachate ◽  
Reactive Transport ◽  
Volatile Fatty Acids ◽  
Transport Model ◽  
Calcium Carbonate Precipitation ◽  
Transport Modelling ◽  
Inorganic Particles ◽  
The Media ◽  
Multiple Species

A numerical, multiple-species, reactive transport model, coupled to models of kinetic biodegradation, precipitation, and particle attachment and detachment for predicting landfill leachate-induced clogging in porous media for one-dimensional flow systems, is described. The finite-element method is used for transport modelling, with reactions incorporated into point-source or sink terms. The species modelled include three volatile fatty acids, active and inert suspended biomass, dissolved calcium, and inorganic particles. The clog matter consists of active biofilm, inert biofilm, and inorganic solids. A biofilm model is used to simulate the growth and decay of active biomass and removal of substrate. Precipitate accumulation and calcium removal are simulated by a model of calcium carbonate precipitation. Interphase movement between clog matter and fluid includes the processes of attachment and detachment. A geometric representation of the porous media allows porosity and specific surface to be estimated from the thickness of the accumulated clog matter. The porosity of the media can thus change spatially and temporally. The behaviour of the model is demonstrated with a hypothetical example.Key words: clogging, landfills, leachate collection systems, modelling, biofilms, mineral precipitation.

Thermal Analysis of Gas Insulated Bus Based on Multiple Species Transport Technique

2014 ◽  
Vol 986-987 ◽  
pp. 980-984
Author(s):  
Yang Zhang ◽  
Cui Ling Shao ◽  
Shuang Shuang Tian
Keyword(s):  
Heat Transfer ◽  
Field Distribution ◽  
Convection Heat Transfer ◽  
Ambient Air ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient ◽  
Species Transport ◽  
Solution Region ◽  
Multiple Species ◽  
Transport Technique

The temperature field distribution is a most important part we pay close attention to when gas insulated bus is designed. In this paper, finite element method is employed to calculate the temperature rise of gas insulated bus based on fluid governing equation and heat conduction equation. The problem of convection heat transfer between fluid and solid is solved by multiple species transport technique which provides convenience for the calculation of convection heat transfer coefficient. The solution region includes SF6 gas, ambient air, conduct and tank whose electrical and thermal properties are dependent of temperature. Analysis result illustrates that the thermal field distribution is symmetrical, the lowest temperature is at the bottom of the tank, while the highest temperature is on the top of the conductor.

scholarly journals High mixing performances of shear-thinning fluids in two-layer crossing channels micromixer at very low Reynolds numbers

2019 ◽  
Vol 13 (4) ◽  
pp. 5938-5960
Author(s):  
A. Kouadri ◽  
Y. Lasbet ◽  
M. Makhlouf
Keyword(s):  
Reynolds Number ◽  
Power Law ◽  
Transport Model ◽  
Tangential Velocity ◽  
Reynolds Numbers ◽  
Mixing Efficiency ◽  
Species Transport ◽  
Industrial Sectors ◽  
Power Law Fluids ◽  
Power Law Index

In a recent study, the Two-Layer Crossing Channels Micromixer (TLCCM) exhibited good mixing capacities in the case of the Newtonian fluids (close to 100%) for all considered Reynolds number values. However, since the majority of the used fluids in the industrial sectors are non-Newtonians, this work details the mixing evolution of power-law fluids in the considered geometry. In this paper, the power-law index ranges from 0.73 to 1 and the generalized Reynolds number is bounded between 0.1 and 50. The conservation equations of momentum, mass and species transport are numerically solved using a CFD code, considering the species transport model. The flow structure at the cross-sectional planes of our micromixer was studied using the dynamic systems theory. The evolutions of the intensity, also the axial, radial and tangential velocity profiles were examined for different values of the Reynolds number and the power-law index. Besides, the pressure drop of the power-law fluids under different Reynolds number was calculated and represented. Furthermore, the mixing efficiency is evaluated by the computation of the mixing index (MI), based on the standard deviation of the mass fraction in different cross-sections. In such geometry, a perfect mixing is achieved with MI closed to 99.47 %, at very small Reynolds number (from the value 0.1) whatever the power-law index and generalized Reynolds numbers taken in this investigation. Consequently, the targeted channel presents a useful tool for pertinent mass transfer improvements, it is highly recommended to include it in various microfluidic systems.

Hydrogenic species transport model for ceramic alumina used in ITER ICRH H&CD & Diagnostics Systems

2007 ◽  
Vol 82 (15-24) ◽  
pp. 2647-2654 ◽  
Author(s):  
C. Moreno ◽  
L.A. Sedano ◽  
K.J. McCarthy ◽  
E.R. Hodgson
Keyword(s):  
Transport Model ◽  
Species Transport

Numerical Modeling and Simulation of Condensation Heat Transfer in a Bundle of Transport Membrane Tubes for Waste Heat and Water Recovery

2011 ◽  
Author(s):  
Cheng-Xian Charlie Lin ◽  
Dexin Wang ◽  
Ainan Bao
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Flue Gas ◽  
Transport Model ◽  
Waste Heat ◽  
Numerical Study ◽  
Tube Bundle ◽  
Inlet Temperature ◽  
Water Recovery ◽  
Species Transport

In this paper, a numerical study has been carried out to investigate the heat and mass transfer with condensation in a transport membrane tube bundle, which is used for recovering both heat and water from combustion flue gas. The tube wall is made of a specially designed porous material that is able to extract condensate liquid from the flue gas. The flue gas investigated consists of one condensable water vapor (H2O) and three noncondensable gases (CO2, O2, and N2). A simplified multi-species transport model was developed for the heat and mass transfer of flue gas. The condensation-evaporation process was simulated as a two-step chemical reaction. The RNG two-equation turbulence model was used for the turbulent flow. The numerical study was conducted within ranges of Reynolds number of 1.0×103–7×104 based on hydraulic diameter of flue gas channel, and 6.4×100–3.3×102 based on inner diameter of the water tube. Flue gas inlet temperature is within the range of 333.2–360.9 K, while the water inlet temperature is within the range of 293.9–316.7 K. Numerical results were compared with experimental data obtained in a parallel effort. It has been found that the developed multi-species transport model was able to predict the flue gas heat and mass transfer in the tube bundle with fairly good accuracy. The heat and mass depletion levels decrease with the increase of the flue gas Reynolds numbers. A new Nusselt number correlation was developed for flue gas convection in the tube bundle. Detailed results about temperature, mass fraction, enthalpy, and skin fraction factors are also presented and discussed.

2D modelling of clogging in landfill leachate collection systems

2008 ◽  
Vol 45 (10) ◽  
pp. 1393-1409 ◽  
Author(s):  
A. J. Cooke ◽  
R. Kerry Rowe
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Landfill Leachate ◽  
Transport Model ◽  
Point Sources ◽  
Time Step ◽  
Leachate Collection ◽  
Aspect Ratios ◽  
The Media ◽  
Multiple Species

A 2D model for predicting clogging of a landfill leachate collection system and subsequent leachate surface position (mounding) is described. A transient finite element fluid flow model is combined with a reactive, multiple-species finite element transport model. The transport model considers biological growth and biodegradation, precipitation, and particle attachment and detachment. It uses a geometrical relationship to establish porosity from the computed thickness of the accumulated clog matter and a relationship between the porosity and hydraulic conductivity of elements in the system. The model represents the flow path within the drainage layer in profile. An iterative method is used to solve for the new hydraulic heads, surface and internal nodal positions, and redistributed clog properties (clog quantity, porosity, hydraulic conductivity) for each element and for each time step. The porosity (and consequently hydraulic conductivity) of the media can therefore change spatially and temporally. The mesh is regenerated automatically each time step (including the addition or subtraction of nodes) taking into account allowable element aspect ratios, the interfaces between differing hydrostratigraphic layers, and static point sources and openings. An integrated alternate solution for very thin mounds is included. The application of the model is demonstrated using a hypothetical field case.

Sign in / Sign up

Export Citation Format

Share Document