scholarly journals Water renewal timescales in an ecological reconstructed lagoon in China

2013 ◽  
Vol 15 (3) ◽  
pp. 991-1001 ◽  
Author(s):  
Xueping Gao ◽  
Yuanyuan Chen ◽  
Chen Zhang
Keyword(s):  
Exposure Time ◽  
Diffusion Processes ◽  
Three Dimensional ◽  
Pollution Source ◽  
Tidal Inlet ◽  
Wind Condition ◽  
Water Renewal ◽  
Transport And Diffusion ◽  
Ecological Reconstruction ◽  
And Diffusion

To improve water quality and construct a landscape lagoon in China, an ecological reconstruction plan for the Qilihai Lagoon (Changli County, Hebei) is proposed. A three-dimensional numerical model (EFDC) was used to study the water renewal capacity in the reconstructed lagoon by using residence time, exposure time and connectivity as timescales. The influences of wind and the depth of the tidal inlet of the lagoon on water renewal capacity were also investigated. The results show that the transport and diffusion processes in the lagoon were strongly influenced by wind and the modification of the tidal inlet. The lagoon under a no wind condition exhibited a low water renewal capacity, especially at the end areas (exposure time, 700–1,000 days). The wind action notably enhanced the water renewal capacity in the lagoon, and the exposure times were all lower than 400 days in the whole region. The optimal inlet depth for the water renewal in the lagoon was predicted to be 4.0 m. The connectivity matrices identified which areas of the domain would be most affected by a pollution source under different conditions. This study examines transport and diffusion processes in a reconstructed lagoon, which could be informative for ecological reconstruction planning.

On the Physics of Anomalies of Boron Nanosegregation at Dislocations in FeAl

2019 ◽  
Vol 391 ◽  
pp. 246-250
Author(s):  
Yuriy S. Nechaev ◽  
Andreas Öchsner
Keyword(s):  
Mechanical Properties ◽  
Critical Analysis ◽  
Diffusion Processes ◽  
Three Dimensional ◽  
Atom Probe ◽  
Atomic Scale ◽  
Metallic Materials ◽  
Probe Field ◽  
Ion Microscopy ◽  
And Diffusion

We present results of the constructive critical analysis and interpretation of some recent studies (Blavette, Sauvage, Wilde and others) at the atomic scale (using three-dimensional atom-probe field-ion microscopy) of impurity nanosegregation at dislocations, including “Cottrell atmospheres”, and grain boundaries in deformed intermetallics and metallic materials, and their relevance to mechanical properties and diffusion processes.

scholarly journals VERIFICATION OF THE DIFFUSION AND TRANSPORT SOLVERS WITHIN DIF3D FOR 3D HEXAGONAL GEOMETRIES

2021 ◽  
Vol 247 ◽  
pp. 10030
Author(s):  
A. G. Nelson ◽  
M. A. Smith ◽  
F. Heidet
Keyword(s):  
National Laboratory ◽  
Argonne National Laboratory ◽  
Three Dimensional ◽  
Analytic Solutions ◽  
Specific Level ◽  
Structured Grid ◽  
Design Activities ◽  
Transport And Diffusion ◽  
High Level ◽  
And Diffusion

The DIF3D code (DIFfusion 3D) has been a workhorse of fast reactor analysis work at Argonne National Laboratory for over 40 years. DIF3D was primarily built in the late 1970s as a three-dimensional multigroup diffusion equation solver operating on semi-structured grid geometries. In the mid-1990s, transport capabilities needed for high-leakage reactor configurations were added to DIF3D with the variational anisotropic nodal transport approach. Recent reactor design activities at Argonne are requiring that a thorough verification of the Argonne Reactor Computation (ARC) codes be performed. With DIF3D being central to the entire ARC system, the verification efforts are focused on the 3D Cartesian, 3D triangular, and 3D hexagonal core geometry options of DIF3D. Validation activities, while needed for the ongoing design activities at Argonne, are handled at a project-specific level. This paper summarizes the verification work so far on the forward and adjoint forms of the fixed source, inhomogeneous fixed source, and k-eigenvalue steady state transport and diffusion equations as implemented specifically for 3D triangular and hexagonal geometries in DIF3D. Since analytic solutions of the neutron diffusion and transport equations are either limited in scope or not possible, this verification required multiple tiers of problems unique to each solver and geometry type, each testing features independent and complementary arguments for why this separate testing of functionalities is acceptable. This separate testing was also supplemented with a high-level integral check of each the diffusion and transport capabilities and applicable geometries.

Towards water quality models

1993 ◽  
Vol 343 (1669) ◽  
pp. 569-584 ◽  
Keyword(s):  
Water Quality ◽  
Three Dimensional ◽  
Metal Interactions ◽  
The North ◽  
The North Sea ◽  
Transport And Diffusion ◽  
Three Dimensional Models ◽  
Component Models ◽  
Water Quality Models ◽  
And Diffusion

Predictions of water quality involve the modelling both of physical processes, which underlie the transport and diffusion of all constituents, and of the sources, sinks, partitioning and interactive processes individual to those constituents. These processes are outlined, together with complementary modelling approaches: (i) development of sophisticated three-dimensional models to represent the physics, and sub-models of suspended sediment, microbiology and metal interactions for processes controlling nutrients, dissolved oxygen, phytoplankton, detritus and metals; (ii) a framework to link these component models; (iii) an accessible model with simpler physics for wide use in simulating constituent distributions, for comparison with measurements to infer sources, sinks and interactions. The North Sea Project measurements provide an input in process evaluation, and data to test the models.

scholarly journals ASSESSMENT OF GEOECOLOGICAL CONSEQUENCES OF SUBDUCTION PROCESSES

2021 ◽  
Vol 1 (6) ◽  
pp. 79-83
Author(s):  
M.V. Zaretskaya ◽  
◽  
V.V. Lozovoy ◽  
Keyword(s):  
Diffusion Equation ◽  
Volcanic Activity ◽  
Model Problem ◽  
Block Structure ◽  
Three Dimensional ◽  
Factorization Method ◽  
Integral Representations ◽  
Transport And Diffusion ◽  
Numerical Analytical Method ◽  
And Diffusion

t. The aim of the work is to develop a numerical-analytical method for assessing the geoecological consequences of volcanic activity accompanying the subduction process. The boundary problem was formulated, including the three-dimensional transport and diffusion equation and boundary conditions at the bottom and surface of the water. For research, a block structure with quasi-homogeneous layers is introduced. In each block, a differential factorization method is implemented and integral representations of solutions are obtained. Calculations for a model problem are carried out, conclusions are formulated about the features of the behavior of the heavy and light fractions of volcanic ejections depending on the speed of currents, intensity and duration of the eruption.

scholarly journals Taste of time: A porous-medium model for human tongue surface with implications for early taste perception

2019 ◽  
Author(s):  
Zhenxing Wu ◽  
Kai Zhao
Keyword(s):  
Porous Medium ◽  
Diffusion Processes ◽  
Molecular Size ◽  
Transport Processes ◽  
Taste Perception ◽  
Taste Intensity ◽  
Human Tongue ◽  
Tongue Surface ◽  
Transport And Diffusion ◽  
And Diffusion

AbstractMost sensory systems are remarkable in their temporal precision, reflected in such phrases as “a flash of light” or “a twig snap”. Yet, the temporal response of human taste perception is complicated by the transport and diffusion processes of the stimuli through the papillae, saliva, taste pore, etc., to reach the taste receptors, processes that are poorly understood. In this study, we addressed this knowledge gap by modeling the transport and diffusion processes within the tongue surface through a novel micro-fiber porous medium approach and found that time-concentration profiles within the papilla zone rises with significant delay that well match experimental ratings of perceived taste intensity for both rapid stimuli pulses and longer sip-and-hold exposures. Diffusivity of taste stimuli, determined mostly by molecular size, correlates greatly with time and slope to reach peak intensity: smaller molecular size may lead to quicker taste perception. Our study demonstrates the novelty of modeling the human tongue as a porous material to drastically simplify computational approaches and that peripheral transport processes may significantly affect the temporal profile of taste perception.

The Numerical Simulation of Airflow and Dispersion in Three-Dimensional Atmospheric Recirculation Zones

1991 ◽  
Vol 30 (7) ◽  
pp. 1005-1024 ◽  
Author(s):  
Paul Dawson ◽  
David E. Stock ◽  
Brian Lamb
Keyword(s):  
Surface Layer ◽  
Atmospheric Transport ◽  
Three Dimensional ◽  
Field Measurements ◽  
Ground Level ◽  
Turbulence Closure ◽  
Numerical Code ◽  
Recirculation Zones ◽  
Transport And Diffusion ◽  
And Diffusion

Abstract A three-dimensional, nonhydrostatic numerical code using the two-equation turbulence closure was developed to model the atmospheric transport and diffusion of pollutants over buildings and a three-dimensional hill. The standard engineering two-equation, first-order turbulence closure was modified to account for surface layer effects and the reduced production of dissipation in the region above the surface layer found in an atmospheric boundary layer. The computations for the dispersion of a building rooftop release showed good agreement with wind tunnel measurements, except when very close to the ground. The transport and dispersion of a plume over a 300-m conical hill, Steptoe Butte, was also simulated. The computations are compared with near ground-level field measurements.

Transport and diffusion processes in trehalose–water solutions: Theory and experiments

2006 ◽  
Vol 330 (1-2) ◽  
pp. 90-100 ◽  
Author(s):  
S. Magazù ◽  
G. Maisano ◽  
F. Migliardo ◽  
N.P. Malomuzh ◽  
E.V. Orlov
Keyword(s):  
Diffusion Processes ◽  
Water Solutions ◽  
Transport And Diffusion ◽  
And Diffusion ◽  
Theory And Experiments
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