Analytical Transport Network Theory for Onsager, Coupled Flows: Part 2—Network-Scale Modeling of Linear, Electrokinetic Flow

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Transport Network ◽  
Scale Model ◽  
Computationally Efficient ◽  
Coupled Flow ◽  
Electrokinetic Flow ◽  
Network Scale ◽  
Energy Conversion And Storage ◽  
Storage Technologies

Abstract The analytical transport network (ATN) model was developed to study transport through heterogeneous and hierarchical microstructural networks. Here, ATN is extended to electrokinetic flow, a linear, coupled flow that satisfies Onsager’s reciprocity relations. In Part 1, a channel-scale model was developed to describe electrokinetic flow through a channel of arbitrary morphology. In Part 2, we exploit the computational economy of the channel-scale model to develop an efficient network-scale model of electrokinetic flow in large, geometrically complex material structures. The corresponding algorithm for applying the theory to voxel-based, three-dimensional (3D) images is automated and computationally efficient. In addition, it provides a means for rapidly obtaining a structure’s tortuosity factor from a 3D image. We outline the manner in which morphology and topology exerts an additional influence on electrokinetic flow relative to pure conduction and viscous fluid flow. The effort represents an important initial step in extending the ATN approach to a broader range of linear and eventually nonlinear coupled flow phenomena. The extension is relevant to a number of technological fields, including emerging energy conversion and storage technologies.

Analytical Transport Network Theory for Onsager, Coupled Flows: Part 1—Channel-Scale Modeling of Linear, Electrokinetic Flow

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Alex P. Cocco ◽  
Kyle N. Grew
Keyword(s):  
Three Dimensional ◽  
Initial Step ◽  
Transport Network ◽  
Scale Model ◽  
Coupled Flow ◽  
Electrokinetic Flow ◽  
Element Analysis ◽  
Onsager Reciprocity ◽  
Flow Phenomena ◽  
Flow Through

Abstract The analytical transport network (ATN) model for flow through microstructural networks is extended to linearly coupled flows subject to Onsager reciprocity. Electrokinetic flow is used as an example system. Through the extension, we gain an improved understanding of if, and how, morphology and topology influence coupled flow systems differently than un-coupled flows. In Part 1, a channel-scale model is developed to describe electrokinetic flow through a channel of arbitrary morphology. The analytical model agrees well with finite element analysis (FEA), but is significantly less expensive in terms of computational resources, and, furthermore, offers general insight into morphology's additional influence on coupled flows relative to uncoupled flows. In Part 2, we exploit these savings to develop a computationally economical, network-scale model and associated algorithm for its implementation to voxel-based three-dimensional images. Included in the algorithm is a means for rapidly calculating a structure's tortuosity factor. This modeling effort represents an important initial step in extending the ATN approach to coupled flow phenomena relevant to emerging technologies that rely on heterogeneous, hierarchical materials.

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

2020 ◽  
Vol 64 (2) ◽  
pp. 20506-1-20506-7
Author(s):  
Min Zhu ◽  
Rongfu Zhang ◽  
Pei Ma ◽  
Xuedian Zhang ◽  
Qi Guo
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Scale Model ◽  
Microscopic Image ◽  
Multi Scale ◽  
Gaussian Pyramid ◽  
Cost Aggregation ◽  
Dimensional Reconstruction ◽  
Image Pairs ◽  
Accurate Matching

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

Modeling and Assessment of the Produced Water Discharges from Offshore Petroleum Platforms

2007 ◽  
Vol 42 (4) ◽  
pp. 303-310 ◽  
Author(s):  
Zhi Chen ◽  
Lin Zhao ◽  
Kenneth Lee ◽  
Charles Hannath
Keyword(s):  
Random Walk ◽  
Produced Water ◽  
Model Development ◽  
Three Dimensional ◽  
Monitoring Program ◽  
Ecological Monitoring ◽  
Numerical Approach ◽  
Ocean Model ◽  
Scale Model ◽  
Water Stream

Abstract There has been a growing interest in assessing the risks to the marine environment from produced water discharges. This study describes the development of a numerical approach, POM-RW, based on an integration of the Princeton Ocean Model (POM) and a Random Walk (RW) simulation of pollutant transport. Specifically, the POM is employed to simulate local ocean currents. It provides three-dimensional hydrodynamic input to a Random Walk model focused on the dispersion of toxic components within the produced water stream on a regional spatial scale. Model development and field validation of the predicted current field and pollutant concentrations were conducted in conjunction with a water quality and ecological monitoring program for an offshore facility located on the Grand Banks of Canada. Results indicate that the POM-RW approach is useful to address environmental risks associated with the produced water discharges.

Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES

2012 ◽  
Author(s):  
Adra Benhacine ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar ◽  
Nabil Kharoua
Keyword(s):  
Convex Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Scale Model ◽  
Wall Jet ◽  
Potential Core ◽  
Flat Surfaces ◽  
Free Jet ◽  
Eddy Simulation

A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

Direct simulation of evolution and control of three-dimensional instabilities in attachment-line boundary layers

1995 ◽  
Vol 291 ◽  
pp. 369-392 ◽  
Author(s):  
Ronald D. Joslin
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
Attachment Line

The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier–Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic-source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in flat-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.

A Fast View Synthesis Implementation Method for Light Field Applications

2021 ◽  
Vol 17 (4) ◽  
pp. 1-20
Author(s):  
Wei Gao ◽  
Linjie Zhou ◽  
Lvfang Tao
Keyword(s):  
Neural Networks ◽  
Light Field ◽  
Three Dimensional ◽  
Super Resolution ◽  
View Synthesis ◽  
Compact Representation ◽  
Light Weight ◽  
Computationally Efficient ◽  
Full Resolution ◽  
Time Systems

View synthesis (VS) for light field images is a very time-consuming task due to the great quantity of involved pixels and intensive computations, which may prevent it from the practical three-dimensional real-time systems. In this article, we propose an acceleration approach for deep learning-based light field view synthesis, which can significantly reduce calculations by using compact-resolution (CR) representation and super-resolution (SR) techniques, as well as light-weight neural networks. The proposed architecture has three cascaded neural networks, including a CR network to generate the compact representation for original input views, a VS network to synthesize new views from down-scaled compact views, and a SR network to reconstruct high-quality views with full resolution. All these networks are jointly trained with the integrated losses of CR, VS, and SR networks. Moreover, due to the redundancy of deep neural networks, we use the efficient light-weight strategy to prune filters for simplification and inference acceleration. Experimental results demonstrate that the proposed method can greatly reduce the processing time and become much more computationally efficient with competitive image quality.

Prediction of Slamming Loads on Catamaran Wetdeck Using CFD

2015 ◽  
Author(s):  
Ahmed Swidan ◽  
Giles Thomas ◽  
Dev Ranmuthugala ◽  
Irene Penesis ◽  
Walid Amin ◽  
...  
Keyword(s):  
Model Simulation ◽  
Three Dimensional ◽  
Grid Method ◽  
Computationally Efficient ◽  
Overset Grid ◽  
Force Magnitude ◽  
Overset Grid Method ◽  
Drop Tests ◽  
Transient Velocity ◽  
Transient Velocity Profile

Wetdeck slamming is one of the principal hydrodynamic loads acting on catamarans. CFD techniques are shown to successfully characterise wetdeck slamming loads, as validated through a series of controlled-speed drop tests on a three-dimensional catamaran hullform model. Simulation of water entry at constant speed by applying a fixed grid method was found to be more computationally efficient than applying an overset grid. However, the overset grid method for implementing the exact transient velocity profile resulted in better prediction of slam force magnitude. In addition the splitting force concurrent with wetdeck slam event was quantified to be 21% of the vertical slamming force.

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