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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Impact Tsunami Calculations: Hydrodynamical Simulations vs. Linear Theory

Tsunamis generated by the impacts of asteroids and comets into the Earth oceans are widely recognized as a potential catastrophic hazard to the Earth s population. Our general conclusion is that linear theory is a reasonably accurate guide to behavior of tsunamis generated by impactors of moderate size, where the initial transient impact cavity is of moderate depth compared to the ocean depth. This is particularly the case for long wavelength waves that propagate fastest and would reach coastlines first. Such tsunamis would be generated in the open ocean by impactors of 300 meters in diameter, which might be expected to strike the Earth once every few thousand years, on the average. Larger impactors produce cavities deep enough to reach the ocean floor; even here, linear theory is applicable if the starting point is chosen at a later phase in the calculation when the impact crater has slumped back to produce a cavity of moderate depth and slope.

Korycansky, E.↗
NASA NTRS2007

The Three Tsunamis

We often talk about how different our world is from our parent's world. We then extrapolate this thinking to our children and try to imagine the world they will face. This is hard enough. However, change is changing! The rate at which change is occurring is accelerating. These new ideas, technologies and ecologies appear to be coming at us like tsunamis. Our approach to responding to these oncoming tsunamis will frame the future our children will live in. There are many of these tsunamis; I am just going to focus on three really big ones heading our way.

Antcliff, Richard R.↗
NASA NTRS2012

Assessing Tsunami Vulnerabilities of Geographies with Shallow Water Equations

Tsunami preparedness is crucial for saving human lives in case of disasters that involve massive water movement. In this work, we develop a framework for visual assessment of tsunami preparedness of geographies. Shallow water equations (also called Saint Venant equations) are a set of hyperbolic partial differential equations that are derived by depth-integrating the Navier-Stokes equations and provide a great abstraction of water masses that have lower depths compared to their free surface area. Our specific contribution in this study is to use Microsoft's XNA Game Studio to import underwater and shore line geographies, create different tsunami scenarios, and visualize the propagation of the waves and their impact on the shore line geography. Most importantly, we utilized the computational power of graphical processing units (GPUs) as HLSL based shader files and delegated all of the heavy computations to the GPU. Finally, we also conducted a validation study, in which we have tested our model against a controlled shallow water experiment. We believe that such a framework with an easy to use interface that is based on readily available software libraries, which are widely available and easily distributable, would encourage not only researchers, but also educators to showcase ideas.

Aras, Rifat↗
NASA NTRS2017

Contribution of Asteroid Generated Tsunami to the Impact Hazard

The long-standing uncertainty about the importance of asteroid-generated tsunami was addressed at a workshop in August 2016, co-sponsored by NASA and NOAA. Experts from NASA, NOAA, the DoE tri-labs (LLNL, SNL, and LANL), DHS, FEMA, and academia addressed the hazard of tsunami created by asteroid impacts, focusing primarily on NEAs with diameter less than 250m. Participants jointly identified key issues and shared information for nearly a year to coordinate their results for discussion at the workshop. They used modern computational tools to examine 1) Near-field wave generation by the impact; 2) Long-distance wave propagation; 3) Damage from coastal run-up and inundation, and associated hazard. The workshop resulted in broad consensus that the asteroid impact tsunami threat is not as great as previously thought.

Asteroid↗
DOE OSTI2019

Initial Application of TSUNAMI for Validation of Advanced Fuel Systems

A number of advanced reactor concepts and accident-tolerant fuels (ATFs) are under development or in the initial stages of deployment and testing in the nuclear power industry. Many of these concepts incorporate chemical or material forms that have not traditionally been used in the nuclear industry and may present challenges for nuclear criticality safety validation. Sensitivity/uncertainty methods are ideally suited for assessing the applicability of existing critical experiments to these potentially challenging applications. This paper presents two case studies recently completed at Oak Ridge National Laboratory (ORNL) which investigated the use of the TSUNAMI tools within the SCALE code system to perform such assessments.Many advanced reactor concepts include uranium enrichments above 5 wt% 235U but below the 20 wt% limit of low-enriched uranium (LEU). This material, referred to as high assay LEU (HA-LEU), poses difficulties across the entire infrastructure of nuclear power, including enrichment, transportation, fabrication, and storage. A potentially representative transportation package was selected to perform a criticality safety validation assessment for UF6 containing HA-LEU. Sensitivity data were generated using the TSUNAMI-3D sequence, and an assessment of the applicability of a range of critical experiments was performed using the TSUNAMI-IP tool. The critical experiments were drawn from the set of available sensitivity data files distributed with the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook. The results indicate that a sufficient number of available experiments may be available to perform validations for these systems.Many different cladding materials and fuel dopants are included in ATFs to mitigate the consequences of a loss of coolant accident. Some of these systems have already been fabricated and introduced as lead test assemblies in commercial reactors, while others are still being developed. Several concepts were considered for pressurized-water reactors (PWRs) and boiling-water reactors (BWRs) in comparison to the current Zircaloy and UO2 fuel system. In most of these cases, the ATF materials did not significantly impact the number of applicable experiments for validation. Some fuel and cladding materials were identified, however, which may reduce the number of available experiments and which will increase the nuclear data–induced uncertainty in neutron multiplication.

Marshall, William (B.J.)↗
DOE OSTI2015

Use of tsunami in the validation of scale 6.1 for the Swedish spent fuel repository - 14381

In March 2011 SKB applied to the Swedish Radiation Safety Authority (SSM) for a permit to build a final repository for spent Fuel and an encapsulation plant (Clink). The application contained a criticality safety analysis for the canisters to be used in Clink and the copper canister to be used in the final repository. In 2012 SSM requested several updates to the application. One of SSM's concerns was the validation of the codes. SSM emphasized that SKB must improve the method to select critical experiments to the validation suite. To satisfy this demand, SKB used the tool Tsunami in the Scale 6.1 code package to select experiments from the handbook of criticality experiment (IHECSBE). With help of sensitivity files SKB evaluated almost 700 experiments from the LEU-COMP-THERM library. SKB then picked the experiments that most resembled our safety cases. The sensitivity coefficient, ck, from Tsunami has been used to evaluate the similarity between the experiments and the applications. It has been considered that a ck over 0.8 provides a 'good enough' similarity between the experiment and our evaluated safety cases. For the different safety cases between 50-600 experiments satisfied the 0.8 criteria giving a good base of data for statistical analysis. It is worth noticing that PWR-fuel generally receives a higher ck than BWR fuel. Initial analysis shows that the differences in results between BWR and PWR can be explained by a larger sensitivity for the U{sup 238} n,n' part of the cross section in the PWR cases. To make sure the validation covers all materials and required physical parameters a gap analysis was made using engineering judgement by criticality safety experts. From this exercise additional experiments were added to the suite. This paper will discuss the Tsunami results for different safety cases and the reasons for differences between them. It will also present the final results of the validation and discuss experiments that were excluded from the validation suite. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Investigation of the continuous-energy sensitivity methods in scale 6.2 using Tsunami-3D - 14579

The SCALE 6.1 code system includes a multigroup (MG) method for three-dimensional (3D) sensitivity analyses via the Tools for Sensitivity and Uncertainty Analysis Methodology Implementation (TSUNAMI), and the upcoming release of SCALE 6.2 will feature the system's first implementation of continuous-energy (CE) sensitivity methods. Detailed information regarding the CE TSUNAMI-3D eigenvalue sensitivity methods is provided in a companion paper. This work compares the results of TSUNAMI-3D calculations using the traditional MG approach to the new CE CLUTCH method in SCALE 6.2. The systems examined in this study include combinations of fast, thermal, and mixed spectra with metal, compound, and solution material forms. The primary fissile species include low-enriched uranium, intermediate-enriched uranium, high-enriched uranium, plutonium, and mixed uranium and plutonium. This broad range of systems expands the experience base with the CE CLUTCH method, identifies best practices for using the code, and provides generic user guidance for utilizing this new capability. Additionally, the study demonstrates the accuracy and usefulness of the CE CLUTCH method, especially for systems for which MG methods perform poorly. (authors)

42 ENGINEERING↗
DOE OSTI2013

Tsunami and acoustic-gravity waves in water of constant depth

A study of wave radiation by a rather general bottom displacement, in a compressible ocean of otherwise constant depth, is carried out within the framework of a three-dimensional linear theory. Simple analytic expressions for the flow field, at large distance from the disturbance, are derived. Realistic numerical examples indicate that the Acoustic-Gravity waves, which significantly precede the Tsunami, are expected to leave a measurable signature on bottom-pressure records that should be considered for early detection of Tsunami.

58 GEOSCIENCES↗
DOE OSTI2014

Identification of earthquakes that generate tsunamis in Java and Nusa Tenggara using rupture duration analysis

Java and Nusa Tenggara are the tectonically active of Sunda arc. This study discuss the rupture duration as a manifestation of the power of earthquake-generated tsunami. We use the teleseismic (30° - 90°) body waves with high-frequency energy Seismometer is from IRIS network as amount 206 broadband units. We applied the Butterworth high bandpass (1 - 2 Hz) filtered. The arrival and travel times started from wave phase of P - PP which based on Jeffrey Bullens table with TauP program. The results are that the June 2, 1994 Banyuwangi and the July 17, 2006 Pangandaran earthquakes identified as tsunami earthquakes with long rupture duration (To > 100 second), medium magnitude (7.6 < Mw < 7.9) and located near the trench. The others are 4 tsunamigenic earthquakes and 3 inland earthquakes with short rupture duration start from To > 50 second which depend on its magnitude. Those events are located far from the trench.

58 GEOSCIENCES↗
DOE OSTI2026

Goal-oriented real-time Bayesian inference for linear autonomous dynamical systems with application to digital twins for tsunami early warning

We present a goal-oriented framework for constructing digital twins with the following properties: (1) they employ discretizations of high-fidelity partial differential equation (PDE) models governed by autonomous dynamical systems, leading to large-scale forward problems; (2) they solve a linear inverse problem to assimilate observational data to infer uncertain model components followed by a forward prediction of the evolving dynamics; and (3) the entire end-to-end, data-to-inference-to-prediction computation is carried out without approximation and in real time through a Bayesian framework that rigorously accounts for uncertainties. Several challenges must be overcome to realize this framework, including the large scale of the forward problem, the high dimensionality of the parameter space, and for a class of problems including those we target, the slow decay of the singular values of the parameter-to-observable map. Here we introduce a methodology to overcome these challenges by exploiting the autonomous structure of the forward model to decompose the solution of the inverse problem into a one-time-only offline phase in which the PDE model is solved a limited number of times (equal to the number of sensors), and an online phase that maps well onto GPUs and computes the parameter inference and prediction of quantities of interest in real time, given observational data. Our ultimate goal is to apply this framework to construct digital twins for subduction zones, including Cascadia, to provide early warning for tsunamis generated by megathrust earthquakes. To this end, we demonstrate how our methodology can be used to employ seafloor pressure observations, along with the coupled acoustic–gravity wave equations, to infer the earthquake-induced spatiotemporal seafloor motion (discretized with $\mathscr{O}$ (10 9 ) parameters) and forward predict the tsunami propagation. We present results of an end-to-end inference, prediction, and uncertainty quantification for a representative test problem with $\mathscr{O}$ (10 8 ) inversion parameters for which goal-oriented Bayesian inference is accomplished exactly and in real time, that is, in a matter of seconds.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Development of SCALE Tools for Sensitivity and Uncertainty Analysis Methodology Implementation (TSUNAMI) from SCALE 5 through SCALE 6.2

This review paper provides an abbreviated historical review of the development of the TSUNAMI capabilities in SCALE, beginning with the first initiatives, to provide new insights into validation, uncertainty quantification, and safety assessment. The tools of TSUNAMI have evolved substantially over two decades to meet the growing application analysis and experiment design needs. Even more advancements are emerging as the next generation of innovators continue to use and develop these tools.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1972

Tides and tsunamis

Although tides and tsunamis are both shallow water waves, it does not follow that they are equally amenable to an observational program using an orbiting altimeter on a satellite. A numerical feasibility investigation using a hypothetical satellite orbit, real tide observations, and sequentially increased levels of white noise has been conducted to study the degradation of the tidal harmonic constants caused by adding noise to the tide data. Tsunami waves, possibly a foot high and one hundred miles long, must be measured in individual orbits, thus requiring high relative resolution.

Zetler, B. D.↗
NASA NTRS1978

Ionospheric and satellite observations for studying the dynamic behavior of typhoons and the detection of severe storms and tsunamis

Atmospheric acoustic-gravity waves associated with severe thunderstorms, tornadoes, typhoons (hurricanes) and tsunamis can be studied through the coupling between the ionosphere and the troposphere. Reverse ray tracing computations of acoustic-gravity waves observed by an ionospheric Doppler sounder array show that wave sources are in the nearby storm systems and that the waves are excited prior to the storms. Results show that ionospheric observations, together with satellite observations, can contribute to the understanding of the dynamical behavior of typhoons, severe storms and tsunamis.

Hung, R. J.↗
NASA NTRS1985

The origin of the 1883 Krakatau tsunamis

Three hypotheses proposed to explain possible causes of the Aug. 27, 1883 Krakatau tsunamis were analyzed: (1) large-scale collapse of the northern part of Krakatau island (Verbeek, 1884), (2) submarine explosion (Yokoyama, 1981), and (3) emplacement of pyroclastic flows (Latter, 1981). A study of timings of the air and sea waves between Krakatau and Batavia, showing that no precise sea wave travel times can be obtained, and a study of the tide and pressure gage records made on August 27, indicating that the air and sea waves were propagated from the focus of eruption on Krakatau island, suggest that neither hypothesis 2 or 3 are sufficiently substantiated. In addition, the event that caused the major air and sea wave was preceded (by 40 min) by a similar, smaller event which generated the second largest tsunami and an air wave. It is concluded that the most likely mechanism for the eruption is a Mt. St. Helens scenario, close to the hypothesis of Verbeek, in which collapse of part of the original volcanic edifice propagated a major explosion.

Francis, P. W.↗
NASA NTRS2003

Impact-generated Tsunamis: An Over-rated Hazard

A number of authors have suggested that oceanic waves (tsunami) created by the impact of relatively small asteroids into the Earth's oceans might cause widespread devastation to coastal cities. If correct, this suggests that asteroids > 100 m in diameter may pose a serious hazard to humanity and could require a substantial expansion of the current efforts to identify earth-crossing asteroids > 1 km in diameter. The debate on this hazard was recently altered by the release of a document previously inaccessible to the scientific community. In 1968 the US Office of Naval Research commissioned a summary of several decades of research into the hazard proposed by waves generated by nuclear explosions in the ocean. Authored by tsunami expert William Van Dorn, this 173-page report entitled Handbook of Explosion-Generated Water Waves affords new insight into the process of impact wave formation, propagation, and run up onto the shoreline.

Melosh, H. J.↗
NASA NTRS2005

Offshore Breaking of Impact Tsunami: Van Dorn was Right

Tsunami generated by the impacts of asteroids and comets into the Earth s oceans are widely recognized as a potentially catastrophic hazard to the Earth s population (e.g. Chapman and Morrison 1994, Nature, 367, 33; Hills et al. 1994, in Hazards Due to Comets and Asteroids, (ed. T. Gehrels), 779; Atkinson et al. 2000, Report of the UK Task Force on Potentially Hazardous NEOs; Ward and Asphaug 2000, Icarus, 145, 64). A peculiarity of ocean impacts is the potential global effects of an impact that would otherwise be of only regional or local importance should it occur on land. This is, of course, due to the ability of waves to propagate globally, as seen by the terrible effects of the recent earthquake off the coast of Sumatra. The overall process of an impact tsunami is complex and falls into several distinct phases: 1) initial impact of the bolide into the ocean and formation of a transient cavity in the water, 2) collapse of the cavity and propagation of large waves from the impact center outward over deep water (typically several km in depth), 3) initial effects on wave amplitude as shallower water of the continental slope is reached ("wave shoaling"), possible breaking of waves in relatively shallow water (less than 100 m depth), on continental shelves, and 5) final contact of waves with the shore and their progression onto dry land ("run-up" and "run-in"). Here we report on numerical calculations (and semi-analytic theory) covering phases 3 and 4.

Korycansky, D. G.↗
NASA NTRS2018

Modeling Issues in Asteroid-Generated Tsunamis

This report studies tsunamis caused by asteroids, both those that arise from atmospheric blast waves moving across the water surface from airburst asteroids, and those that arise when the asteroid reaches the water and forms a crater. We perform numerical experiments that compare simulations using depth-averaged models (shallow water and several forms of Boussinesq) with linearized Euler (acoustics plus gravity) and ALE hydrocode simulations. We find that neither of the depth-averaged models do a good job of initiating the tsunami, but in some cases can be used to propagate a solution generated by a higher-fidelity method. A list of our conclusions and recommendations for further study is given in Section 5.

Berger, Marsha J.↗
NASA NTRS2022

The 28 November 2020 Landslide, Tsunami, and Outburst Flood – A Hazard Cascade Associated With Rapid Deglaciation at Elliot Creek, British Columbia, Canada

We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose. Plain Language Summary Glacier retreat exposes unstable slopes that can suddenly fail. We describe and model one such event with far-reaching consequences. The landslide mass (50 million tonnes, equivalent to the combined mass of all Canadian automobiles) entered and suddenly drained a 0.6-km2 alpine lake in the southern Coast Mountains of British Columbia. Displaced water destroyed salmon-spawning habitat over a distance of 8.5 km and created a plume of sediment and organic matter more than 60 km from the head of the fjord into which the floodwaters discharged. Physically based models are able to simulate the hazard cascade, and such models could be used to improve hazard and risk assessments of these events under future climate change.

M. Geertsema↗