scholarly journals Adaptation of flux-based solvers to 2D two-layer shallow flows with variable density including numerical treatment of the loss of hyperbolicity and drying/wetting fronts

2020 ◽  
Vol 22 (5) ◽  
pp. 972-1014
Author(s):  
J. Murillo ◽  
S. Martinez-Aranda ◽  
A. Navas-Montilla ◽  
P. García-Navarro
Keyword(s):  
Variable Density ◽  
Test Cases ◽  
Exchange Flow ◽  
Time Step ◽  
Tuning Parameters ◽  
Shallow Flows ◽  
Rich Description ◽  
Systems Of Conservation Laws ◽  
The Rich ◽  
Shallow Flow Model

Abstract An important feature of the two-layer shallow flow model is that the resulting system of equations cannot be expressed in conservation-law form. Here, the HLLS and ARoe solvers, derived initially for systems of conservation laws, are reformulated and applied to the two-layer shallow flows in a great variety of problems. Their resulting extension and combination allows us to overcome the loss of the hyperbolic character, ensuring energy or exactly balanced property, guarantees positivity of the solution, and provides a correct drying/wetting advance front without requiring tuning parameters. As a result, in those cases where the rich description of internal and external waves cannot be provided by the ARoe solver, HLLS is applied. Variable density is considered in each layer as a result of a bulk density driven by the mixture of different constituents. A wide variety of test cases is presented confirming the properties of this combination, including exactly balanced scenarios in subcritical and subcritical-transcritical scenarios, dam-break problems over bed variations and wet/dry fronts, non-hyperbolic conditions, transcritical exchange flow with loss of hyperbolicity. Despite the complexity of the test cases presented here, accurate and stable simulations are guaranteed, ensuring positivity of the solution without decreasing the time step.

scholarly journals Is There a Place for Theoretical Frameworks in Qualitative Research?

2021 ◽  
Vol 20 ◽  
pp. 160940692098795
Author(s):  
Casey M. Garvey ◽  
Rachel Jones
Keyword(s):  
Qualitative Research ◽  
Conceptual Understanding ◽  
Inductive Reasoning ◽  
Theoretical Framework ◽  
Theoretical Frameworks ◽  
Common Sense Model ◽  
Rich Description ◽  
The Common ◽  
The Rich ◽  
Qualitative Analyses

Qualitative research proceeds from the position that there is no one observable reality. Researchers utilizing qualitative methods build findings inductively, from raw data to a conceptual understanding. Theoretical frameworks may be utilized to guide qualitative analyses by suggesting concepts and relationships to explore. The framework may provide a sense of the story emerging from the analyses. And concurrently, the rich description provided by the analyses may allow the framework to be more deeply appreciated. However, there is a risk that using a theoretical framework may stifle inductive reasoning or result in findings incongruent to the data. The following is a discussion of the application of a theoretical framework in a qualitative study. This study, guided by the Common-Sense Model, explores the choice to undergo treatment for Hepatitis C Virus among veterans. Examples from the analyses are provided to facilitate discussion on the utilization of a theoretical framework. Techniques to optimize the use of a theoretical framework, as well as mitigate risks of such use, are presented. When utilized alongside rigorous data analyses and introspection, a theoretical framework may serve as a valuable tool to navigate data in qualitative research.

scholarly journals «Strong as Death is Love»: Eros and Education at the End of Time

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Sam D Rocha ◽  
Adi Burton
Keyword(s):  
Social Science ◽  
Song Of Songs ◽  
Leo Tolstoy ◽  
Rich Description ◽  
The Rich ◽  
Extended Reflection ◽  
The Relationship ◽  
Sense Of Urgency

This essay is an extended reflection on the relationship between death and love expressed in a fragment from Song of Songs 8:6: «Strong as death is love». The passage will be analyzed through a Jewish, Orthodox, and Catholic exegesis and literary reflection. In particular, the essay describes the role of a particular form of love (eros) within a particular form of education (education at the end of time). While eros has frequently been ignored or resigned to a purely sexualized role, we will look closely at Augustine’s eulogy of his mother, Monica, in the Confessions, suggesting that perhaps the most visceral expression of eros is to be found in the phenomenology of death. We will also draw on the phenomenological manifestation of death by looking to the rich description of dying provided by Leo Tolstoy in his novella, The Death of Ivan Ilych.Together these investigations of eros and education yield a «curriculum of death», which draws on the re-conceptualist notion of curriculum. Our claim is that this curriculum of death offers a sense of urgency and seriousness found lacking in schools today, where death abounds, but is rarely if ever addressed in a humanistic way. This final methodological emphasis on the humanities elucidates more directly and critically the role of research for a curriculum of death within the dominance of social science in the field of education.

scholarly journals Learning data-driven reduced elastic and inelastic models of spot-welded patches

2021 ◽  
Vol 22 ◽  
pp. 32
Author(s):  
Agathe Reille ◽  
Victor Champaney ◽  
Fatima Daim ◽  
Yves Tourbier ◽  
Nicolas Hascoet ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Structural Response ◽  
Data Driven ◽  
Fine Scale ◽  
Time Step ◽  
Large Structures ◽  
Computational Performance ◽  
Local Patch ◽  
The Rich ◽  
Learning Data

Solving mechanical problems in large structures with rich localized behaviors remains a challenging issue despite the enormous advances in numerical procedures and computational performance. In particular, these localized behaviors need for extremely fine descriptions, and this has an associated impact in the number of degrees of freedom from one side, and the decrease of the time step employed in usual explicit time integrations, whose stability scales with the size of the smallest element involved in the mesh. In the present work we propose a data-driven technique for learning the rich behavior of a local patch and integrate it into a standard coarser description at the structure level. Thus, localized behaviors impact the global structural response without needing an explicit description of that fine scale behaviors.

The Future of Christianity in South and Central Asia

2019 ◽  
pp. 433-444
Author(s):  
Savithri Sumanthiran
Keyword(s):  
Central Asia ◽  
Contextual Theology ◽  
Skilled Workers ◽  
Gender Parity ◽  
Rich Description ◽  
One Belt One Road ◽  
The Future ◽  
Road Project ◽  
The Rich ◽  
The Church

Christianity in Central Asia has had to negotiate between militant atheism and Islam. The challenge in the region remains the proclamation of the gospel amidst diverse ideologies. However, the witness of the Church is challenged by internal disunity. Communities that have been Islamic for centuries are now going back to their roots. Conversion from Islam is perceived as a matter of being an instrument of social fragmentation. Still, the Chinese ‘One Belt, One Road’ project has spawned the need for skilled workers, providing opportunities for Christians to be present in these countries. An important issue for the future of Christianity in the region will be the need to invest in a contextual theology that is able to evangelise without causing offence to the Islamic community. To live out the Christian faith in a convincing way in such a context will involve Christians drawing from their own Scriptures the rich description of the kingdom of God that can shape the entire life of a community. South Asian countries have all seen an improvement in gender parity over the last decades. As Christians live among social strata, they can show the relevance of their message to the contemporary context.

scholarly journals A Universal Law of Estuarine Mixing

2020 ◽  
Vol 50 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Hans Burchard
Keyword(s):  
River Runoff ◽  
Numerical Test ◽  
Test Cases ◽  
Exchange Flow ◽  
One Dimensional ◽  
Estuarine Mixing ◽  
Flow Mixing ◽  
Universal Law ◽  
Total Exchange

AbstractA universal law of estuarine mixing is derived here, combining the approaches of salinity coordinates, Knudsen relations, total exchange flow, mixing definition as salinity variance loss, and the mixing–exchange flow relation. As a result, the long-term average mixing within an estuarine volume bounded by the isohaline of salinity S amounts to M(S) = S2Qr, where Qr is the average river runoff into the estuary. Consequently, the mixing per salinity class is m(S) = ∂SM(S) = 2SQr, which can also be expressed as the product of the isohaline volume and the mixing averaged over the isohaline. The major differences between the new mixing law and the recently developed mixing relation based on the Knudsen relations are threefold: (i) it does not depend on internal dynamics of the estuary determining inflow and outflow salinities (universality), (ii) it is exactly derived from conservation laws (accuracy), and (iii) it calculates mixing per salinity class (locality). The universal mixing law is demonstrated by means of analytical stationary and one-dimensional and two-dimensional numerical test cases. Some possible consequences for the salinity distribution in real estuaries are briefly discussed. Since the mixing per salinity class only depends on the river runoff and the chosen salinity, and not on local processes at the isohaline, low-mixing estuaries must have large isohaline volumes and vice versa.

scholarly journals Accuracy Analysis of a Spectral Element Atmospheric Model Using a Fully Implicit Solution Framework

2010 ◽  
Vol 138 (8) ◽  
pp. 3333-3341 ◽  
Author(s):  
Katherine J. Evans ◽  
Mark A. Taylor ◽  
John B. Drake
Keyword(s):  
Shallow Water Equation ◽  
Time Integration ◽  
Atmospheric Model ◽  
Test Cases ◽  
Implicit Methods ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Fully Implicit ◽  
Stability Limits

Abstract A fully implicit (FI) time integration method has been implemented into a spectral finite-element shallow-water equation model on a sphere, and it is compared to existing fully explicit leapfrog and semi-implicit methods for a suite of test cases. This experiment is designed to determine the time step sizes that minimize simulation time while maintaining sufficient accuracy for these problems. For test cases without an analytical solution from which to compare, it is demonstrated that time step sizes 30–60 times larger than the gravity wave stability limits and 6–20 times larger than the advective-scale stability limits are possible using the FI method without a loss in accuracy, depending on the problem being solved. For a steady-state test case, the FI method produces error within machine accuracy limits as with existing methods, but using an arbitrarily large time step size.

scholarly journals Investigation of Numerical Conditions of Moving Particle Semi-implicit for Two-Dimensional Wedge Slamming

2022 ◽  
Author(s):  
Takahito Iida ◽  
Yudai Yokoyama
Keyword(s):  
Particle Size ◽  
Poor Performance ◽  
Verification And Validation ◽  
Two Dimensional ◽  
Step Size ◽  
Time Step ◽  
Optimum Time ◽  
Time Step Size ◽  
Tuning Parameters ◽  
Moving Particle

AbstractThe sensitivity of moving particle semi-implicit (MPS) simulations to numerical parameters is investigated in this study. Although the verification and validation (V&V) are important to ensure accurate numerical results, the MPS has poor performance in convergences with a time step size. Therefore, users of the MPS need to tune numerical parameters to fit results into benchmarks. However, such tuning parameters are not always valid for other simulations. We propose a practical numerical condition for the MPS simulation of a two-dimensional wedge slamming problem (i.e., an MPS-slamming condition). The MPS-slamming condition is represented by an MPS-slamming number, which provides the optimum time step size once the MPS-slamming number, slamming velocity, deadrise angle of the wedge, and particle size are decided. The simulation study shows that the MPS results can be characterized by the proposed MPS-slamming condition, and the use of the same MPS-slamming number provides a similar flow.

Conclusion: One for the Road

Drunk Japan ◽  
2020 ◽  
pp. 175-184
Author(s):  
Mark D. West
Keyword(s):  
Japanese Society ◽  
The Road ◽  
Railway Company ◽  
Rich Description ◽  
The Rich ◽  
Wrongful Death ◽  
The Way

The conclusion begins with a final case, in which an intoxicated salaryman is run over by a train, as an example of the degree to which cases have both common themes and individual-specific characteristics. In this case the deceased’s heirs sue the railway company for wrongful death, and the railway company countersues for damages incurred in cleaning up the tracks. The court finds no liability for the railway and orders the deceased’s heirs to pay a portion—but not all—of the costs of cleanup. Along the way the court provides such detail that the deceased emerges as a recognizable individual who drank in familiarly patterned ways. The book concludes by analyzing its key findings, focusing on the rich description of alcohol in Japanese society created by courts and their ability to bring individuals to life in their narratives.

Two Dynamical Core Formulation Flaws Exposed by a Baroclinic Instability Test Case

2009 ◽  
Vol 137 (2) ◽  
pp. 790-796 ◽  
Author(s):  
David L. Williamson ◽  
Jerry G. Olson ◽  
Christiane Jablonowski
Keyword(s):  
Baroclinic Instability ◽  
Zonal Flow ◽  
Additive Constant ◽  
Test Case ◽  
Test Cases ◽  
Time Step ◽  
Multiplicative Constant ◽  
Dynamical Core ◽  
Community Atmosphere Model ◽  
Vector Wind

Abstract Two flaws in the semi-Lagrangian algorithm originally implemented as an optional dynamical core in the NCAR Community Atmosphere Model (CAM3.1) are exposed by steady-state and baroclinic instability test cases. Remedies are demonstrated and have been incorporated in the dynamical core. One consequence of the first flaw is an erroneous damping of the speed of a zonally uniform zonal wind undergoing advection by a zonally uniform zonal flow field. It results from projecting the transported vector wind expressed in unit vectors at the arrival point to the surface of the sphere and is eliminated by rotating the vector to be parallel to the surface. The second flaw is the formulation of an a posteriori energy fixer that, although small, systematically affects the temperature field and leads to an incorrect evolution of the growing baroclinic wave. That fixer restores the total energy at each time step by changing the provisional forecast temperature proportionally to the magnitude of the temperature change at that time step. Two other fixers are introduced that do not exhibit the flaw. One changes the provisional temperature everywhere by an additive constant, and the other changes it proportionally by a multiplicative constant.

scholarly journals The Role of Context in Educational RCT Findings: A Call to Redefine “Evidence-Based Practice”

2020 ◽  
Vol 49 (4) ◽  
pp. 285-288 ◽  
Author(s):  
Avi Kaplan ◽  
Jennifer Cromley ◽  
Tony Perez ◽  
Ting Dai ◽  
Kyle Mara ◽  
...  
Keyword(s):  
Evidence Based Practice ◽  
Causal Explanation ◽  
Evidence Based ◽  
Design Based Research ◽  
Effective Implementation ◽  
Causal Mechanisms ◽  
Rich Description ◽  
Integral Role ◽  
The Rich

In this commentary, we complement other constructive critiques of educational randomized control trials (RCTs) by calling attention to the commonly ignored role of context in causal mechanisms undergirding educational phenomena. We argue that evidence for the central role of context in causal mechanisms challenges the assumption that RCT findings can be uncritically generalized across settings. Anchoring our argument with an example from our own multistudy RCT project, we argue that the scientific pursuit of causal explanation should involve the rich description of contextualized causal effects. We further call for incorporating the evidence of the integral role of context in causal mechanisms into the meaning of “evidence-based practice,” with the implication that effective implementation of practice in a new setting must involve context-oriented, evidence-focused, design-based research that attends to the emergent, complex, and dynamic nature of educational contexts.

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