scholarly journals Three-phase numerical model for subsurface hydrology in permafrost-affected regions (PFLOTRAN-ICE v1.0)

2014 ◽  
Vol 8 (5) ◽  
pp. 1935-1950 ◽  
Author(s):  
S. Karra ◽  
S. L. Painter ◽  
P. C. Lichtner
Keyword(s):  
Reactive Transport ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Single Component ◽  
The Arctic ◽  
Freezing And Thawing ◽  
Subsurface Hydrology ◽  
Near Surface ◽  
Three Phase ◽  
Dimensional Simulation

Abstract. Degradation of near-surface permafrost due to changes in the climate is expected to impact the hydrological, ecological and biogeochemical responses of the Arctic tundra. From a hydrological perspective, it is important to understand the movement of the various phases of water (gas, liquid and ice) during the freezing and thawing of near-surface soils. We present a new non-isothermal, single-component (water), three-phase formulation that treats air as an inactive component. This single component model works well and produces similar results to a more complete and computationally demanding two-component (air, water) formulation, and is able to reproduce results of previously published laboratory experiments. A proof-of-concept implementation in the massively parallel subsurface flow and reactive transport code PFLOTRAN is summarized, and parallel performance of that implementation is demonstrated. When water vapor diffusion is considered, a large effect on soil moisture dynamics is seen, which is due to dependence of thermal conductivity on ice content. A large three-dimensional simulation (with around 6 million degrees of freedom) of seasonal freezing and thawing is also presented.

scholarly journals Three-phase numerical model for subsurface hydrology in permafrost-affected regions

2014 ◽  
Vol 8 (1) ◽  
pp. 149-185 ◽  
Author(s):  
S. Karra ◽  
S. L. Painter ◽  
P. C. Lichtner
Keyword(s):  
Reactive Transport ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
The Arctic ◽  
Freezing And Thawing ◽  
Subsurface Hydrology ◽  
Near Surface ◽  
Three Phase ◽  
Dimensional Simulation ◽  
New Formulation

Abstract. Degradation of near-surface permafrost due to changes in the climate is expected to impact the hydrological, ecological and biogeochemical responses of the Arctic tundra. From a hydrological perspective, it is important to understand the movement of the various phases of water (gas, liquid and ice) during the freezing and thawing of near surface soils. We present a new non-isothermal, single-component (water), three-phase formulation that treats air as an inactive component. The new formulation is implemented in the massively parallel subsurface flow and reactive transport code PFLOTRAN. Parallel performance for this implementation is demonstrated, and validation studies using previously published experimental data are performed. A comparison between the new model and a more complete two-component (air–water) multiphase approach shows only minor differences. When water vapor diffusion is considered, a large effect on soil moisture dynamics is seen, which is due to dependence of thermal conductivity on ice content. A large three-dimensional simulation (with around 6 million degrees of freedom) of seasonal freezing and thawing is also presented.

scholarly journals Effective 1D Time-Dependent Schrödinger Equations for 3D Geometrically Correlated Systems

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3033
Author(s):  
Devashish Pandey ◽  
Xavier Oriols ◽  
Guillermo Albareda
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Longitudinal Direction ◽  
Time Dependent ◽  
Ab Initio Molecular Dynamics ◽  
Quantitative Accuracy ◽  
Dimensional Simulation ◽  
Transport Problems ◽  
Computational Resources

The so-called Born–Huang ansatz is a fundamental tool in the context of ab-initio molecular dynamics, viz., it allows effectively separating fast and slow degrees of freedom and thus treating electrons and nuclei with different mathematical footings. Here, we consider the use of a Born–Huang-like expansion of the three-dimensional time-dependent Schrödinger equation to separate transport and confinement degrees of freedom in electron transport problems that involve geometrical constrictions. The resulting scheme consists of an eigenstate problem for the confinement degrees of freedom (in the transverse direction) whose solution constitutes the input for the propagation of a set of coupled one-dimensional equations of motion for the transport degree of freedom (in the longitudinal direction). This technique achieves quantitative accuracy using an order less computational resources than the full dimensional simulation for a typical two-dimensional geometrical constriction and upto three orders for three-dimensional constriction.

Simulation of electromagnetic signal of profile observations from a drifting surface

2020 ◽  
Author(s):  
Polina S. Osipova ◽  
◽  
Arkadiy V. Zlobinskiy ◽  
Vladimir V. Potapov ◽  
◽  
...  
Keyword(s):  
Electric Dipole ◽  
Born Approximation ◽  
Three Dimensional ◽  
Arctic Region ◽  
The Arctic ◽  
Electromagnetic Signal ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
The Arctic Region

As part of the RSF project, the use of a drifting surface on which geophysical installations will be placed is proposed to study the environment in the Arctic region. The proposed method of electrical exploration is sounding with a circular electric dipole as a source. Studying the applicability of the technique requires three–dimensional simulation of the received signal. The paper shows some simulation results using the previously proposed algorithm based on the Born approximation.

scholarly journals Four-dimensional variational inversion of black carbon emissions during ARCTAS-CARB with WRFDA-Chem

2017 ◽  
Vol 17 (12) ◽  
pp. 7605-7633 ◽  
Author(s):  
Jonathan J. Guerrette ◽  
Daven K. Henze
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Degrees Of Freedom ◽  
Variance Reduction ◽  
Regional Climate ◽  
The Arctic ◽  
Near Surface ◽  
Fire Emissions ◽  
Aircraft Observations

Abstract. Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental four-dimensional variational (4D-Var) capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB) and anthropogenic black carbon (BC) aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB) field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network on 22, 23, and 24 June 2008. We consider three BB inventories, including Fire INventory from NCAR (FINN) v1.0 and v1.5 and Quick Fire Emissions Database (QFED) v2.4r8. On 22 June, aircraft observations are able to reduce the spread between a customized QFED inventory and FINNv1.0 from a factor of 3. 5 ( × 3. 5) to only × 2. 1. On 23 and 24 June, the spread is reduced from × 3. 4 to × 1. 4. The posterior corrections to emissions are heterogeneous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The US EPA's 2005 National Emissions Inventory (NEI05) is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is reduced by × 2, where highway sources dominate, while inland sources are increased near Barstow by × 5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and by up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly limited to sources close to observations. We find that the 22 June aircraft observations are able to constrain approximately 14 degrees of freedom of signal (DOF), while surface and aircraft observations together on 23/24 June constrain 23 DOF. Improving hourly- to daily-scale concentration predictions of BC and other aerosols during BB events will require more comprehensive and/or targeted measurements and a more complete accounting of sources of error besides the emissions.

Three-Dimensional Simulation of Nano-Composite Ceramic Tool Materials

2014 ◽  
Vol 1052 ◽  
pp. 86-90
Author(s):  
Song Hao ◽  
Chuan Zhen Huang
Keyword(s):  
Microstructure Evolution ◽  
Boundary Migration ◽  
Three Dimensional ◽  
Phase Field Model ◽  
Tool Material ◽  
Composite Ceramic ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Three Phase ◽  
Dimensional Simulation

A phase field model of three-phase composite ceramic tool materials with two kinds of nanoparticles is set up in this research. The three-dimensional simulation algorithm is modified and a new efficient algorithm is established. The microstructure evolution of three-phase nanoceramic tool materials is more efficiently and successfully simulated in 200x200x200 unit size. Microstructure evolution of single-phase and three-phase ceramic tool materials is simulated respectively. It can be found that the peak value of grain size distribution for three-phase nanoceramic tool material is smaller than average diameter. It indicates that the nanoparticles not only restrain grain boundary migration, but also prevent the elimination of small grains and refine matrix grains.

scholarly journals A Framework for Multi-Objective Optimization of Plate-Fin Heat Exchangers Using a Detailed Three-Dimensional Simulation Model

2021 ◽  
Vol 5 (4) ◽  
pp. 82
Author(s):  
Patrick Haider ◽  
Paul Heinz ◽  
Thomas Acher ◽  
Sebastian Rehfeldt ◽  
Harald Klein
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Three Dimensional ◽  
Unit Weight ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Optimization Routine ◽  
Dimensional Simulation

The design of a multi-stream plate-fin heat exchanger is a highly integrated task with multiple opposing objectives and many degrees of freedom. This work shows how it can be fully or partially automated by the combination of a detailed three-dimensional simulation model and an optimization routine. The desired task is formulated as the target of a multi-objective optimization and solved using a genetic algorithm. The workflow is presented using a cryogenic plate-fin heat exchanger with four process streams. The design is optimized towards high efficiency, low pressure drop, and low unit weight by adjusting the outer geometry, the inlet and outlet distributor configuration, and the detailed stream geometry. A detailed analysis of the Pareto-set gives a good overview of possible solutions, and the optimization routine can automatically find a feasible design with a reasonable tradeoff between the objectives. All elements of the framework are implemented in open source software. A highlight of this research is that a very comprehensive and detailed simulation model is employed in the optimization framework. Thus, the presented method can be easily adjusted to fit the needs of other engineering tasks.

scholarly journals Three-Dimensional Stefan Equation for Thermokarst Lake and Talik Geometry Characterization

2021 ◽  
Author(s):  
Noriaki Ohara ◽  
Benjamin M. Jones ◽  
Andrew D. Parsekian ◽  
Kenneth M. Hinkel ◽  
Katsu Yamatani ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Ground Subsidence ◽  
The Arctic ◽  
Permafrost Region ◽  
Boundary Area ◽  
Near Surface ◽  
Thermokarst Lakes ◽  
Thermokarst Lake ◽  
Permafrost Thaw ◽  
Transient Electromagnetic

Abstract. Thermokarst lake dynamics, which plays an essential role in carbon release due to permafrost thaw, is affected by various geomorphological processes. In this study, we derive a three-dimensional (3D) Stefan equation to characterize talik geometry under a hypothetical thermokarst lake in the continuous permafrost region. Using the Euler equation in the calculus of variations, the lower bounds of the talik were determined as an extremum of the functional describing the phase boundary area with a fixed total talik volume. We demonstrate that the semi-ellipsoid geometry of the talik is optimal for minimizing the total permafrost thaw under the lake for a given annual heat supply. The model predicting ellipsoidal talik geometry was verified by talik thickness observations using transient electromagnetic (TEM) soundings in Peatball Lake on the Arctic Coastal Plain (ACP) of Alaska. The lake width-depth ratio of the elliptic talik can characterize the energy flux anisotropy in the permafrost although the lake bathymetry cross section may not be elliptic due to the presence of near-surface ice-rich permafrost. This theory suggests that talik development stabilizes thermokarst lakes by ground subsidence due to permafrost thaw while wind-induced waves and currents are likely responsible for the elongation and orientation of thermokarst lakes in certain regions such as the ACP of northern Alaska.

scholarly journals Four dimensional variational inversion of black carbon emissions during ARACTAS-CARB with WRFDA-Chem

2016 ◽  
Author(s):  
Jonathan J. Guerrette ◽  
Daven K. Henze
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Degrees Of Freedom ◽  
Variance Reduction ◽  
Regional Climate ◽  
The Arctic ◽  
Near Surface ◽  
Fire Emissions ◽  
Aircraft Observations

Abstract. Biomass burning emissions of atmospheric aerosols, including black carbon, are growing due to increased global drought, and comprise a large source of uncertainty in regional climate and air quality studies. We develop and apply new incremental 4D-Var capabilities in WRFDA-Chem to find optimal spatially and temporally distributed biomass burning (BB) and anthropogenic black carbon (BC) aerosol emissions. The constraints are provided by aircraft BC concentrations from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites in collaboration with the California Air Resources Board (ARCTAS-CARB) field campaign and surface BC concentrations from the Interagency Monitoring of PROtected Visual Environment (IMPROVE) network on 22, 23, and 24 June, 2008. We consider multiple BB inventories, including Fire INventory from NCAR (FINN) v1.0 and v1.5 and Quick Fire Emissions Database (QFED) v2.4r8. On 22 June, aircraft observations are able to reduce the spread between QFED × ⅓ and FINNv1.0 from ×3.5 to ×2.1. On 23 and 24 June, the spread is reduced from ×3.4 to ×1.4. The posterior corrections to emissions are heterogenous in time and space, and exhibit similar spatial patterns of sign for both inventories. The posterior diurnal BB patterns indicate that multiple daily emission peaks might be warranted in specific regions of California. The U.S. EPA's 2005 National Emissions Inventory (NEI05) is used as the anthropogenic prior. On 23 and 24 June, the coastal California posterior is scaled by × ½, where highway sources dominate, while inland sources are increased near Barstow by ×5. Relative BB emission variances are reduced from the prior by up to 35 % in grid cells close to aircraft flight paths and up to 60 % for fires near surface measurements. Anthropogenic variance reduction is as high as 40 % and is similarly limited to sources close to observations. We find that the 22 June aircraft observations are able to constrain approximately 14 degrees of freedom of signal (DOF), while surface and aircraft observations together on 23/24 June constrain 23 DOF. Improving hourly to daily scale concentration predictions of BC and other aerosols during BB events will require more comprehensive and/or targeted measurements and a more complete accounting of sources of error besides the emissions.

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