Large-scale Experimental Facility Research Articles

Plant species phenology differs between climate and land-use scenarios and relates to plant functional traits.

Phenological shifts due to changing climate are often highly species and context specific. Land-use practices such as mowing or grazing directly affect the phenology of grassland species, but it is unclear if plants are similarly affected by climate change in differently managed grassland systems such as meadows and pastures. Functional traits have a high potential to explain phenological shifts and might help to understand species-specific and land-use-specific phenological responses to changes in climate. In the large-scale field experiment Global Change Experimental Facility (GCEF), we monitored the first flowering day, last flowering day, flowering duration, and day of peak flowering, of 17 herbaceous grassland species under ambient and future climate conditions, comparing meadows and pastures. Both climate and land use impacted the flowering phenology of plant species in species-specific ways. We did not find evidence for interacting effects of climate and land-use type on plant phenology. However, the data indicate that microclimatic and microsite conditions on meadows and pastures were differently affected by future climate, making differential effects on meadows and pastures likely. Functional traits, including the phenological niche and grassland utilization indicator values, explained species-specific phenological climate responses. Late flowering species and species with a low mowing tolerance advanced their flowering more strongly under future climate. Long flowering species and species following an acquisitive strategy (high specific leaf area, high mowing tolerance, and high forage value) advanced their flowering end more strongly and thus more strongly shortened their flowering under future climate. We associated these trait-response relationships primarily with a phenological drought escape during summer. Our results provide novel insights on how climate and land use impact the flowering phenology of grassland species and we highlight the role of functional traits in mediating phenological responses to climate.

Modeling of the influence of local heat sources on a light gas stratification formation and erosion in a large-scale experimental facility using eddy resolving numerical approach

The main objective of this work is to evaluate the results of application of Implicit Large Eddy Simulation (ILES) turbulence modeling approach to simulate the complex hydrogen safety problem. The paper presents the results of numerical simulation of the OECD/NEA HYMERES (HYdrogen Mitigation Experiments for Reactor Safety) HP2 series tests in the PANDA facility, aimed at studying the thermal effect of passive autocatalytic recombiner (PAR) operation on mixing the containment atmosphere, using CABARET-SC1 code. The code is based on the eddy resolving CABARET technique, which allows implicit modeling of the subgrid turbulence scales without using tuning parameters (ILES approximation). The natural convection flow inside the PAR model was calculated explicitly using a simplified model of the heating section and the housing. Good agreement of calculated transient with experimental data was obtained, which indicates the effectiveness of such approach.

Heat transfer and interfacial flow physics of microgravity flow boiling in single-side-heated rectangular channel with subcooled inlet conditions – Experiments onboard the International Space Station

This study is the culmination of a long-term collaborative effort between researchers from the Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) and the NASA Glenn Research Center to investigate gravitational effects on flow boiling and flow condensation. The science and design concepts for this large-scale effort were initiated in 2011 and included several studies detailing various aspects of two-phase fluid physics in both Earth gravity and microgravity, culminating in construction of the large-scale experimental facility named “Flow Boiling and Condensation Experiment (FBCE)”. The experiment was launched to the International Space Station (ISS) in August 2021. Following the successful installation of FBCE, equipped with the Flow Boiling Module (FBM), onboard the ISS and completion of several safety checks, flow boiling experiments were performed for five months from February 2022 until July 2022. This resulted in a large flow boiling database covering broad ranges of operating parameters and heating configurations spanning several research objectives. This study investigates microgravity flow boiling of n-perfluorohexane with subcooled inlet in a single-side-heated rectangular channel of dimensions 114.6-mm heated length, 2.5-mm heated width, and 5.0-mm height. Key operating parameters investigated are mass velocity (199.90 – 3200.13 kg/m2s), inlet subcooling (0.10 – 45.76°C), and inlet pressure (113.30 – 164.29 kPa). Images and image sequences acquired via high-speed-video are presented to elucidate the interfacial flow physics. To analyze and explain the effects of various parameters in microgravity, heat transfer results are presented as flow boiling curves, streamwise profiles of wall temperature and heat transfer coefficient, and parametric trends of local and averaged heat transfer coefficient. Mass velocity and inlet subcooling significantly influenced most of the aforementioned aspects of flow boiling, whereas effects of inlet pressure were comparatively insignificant. Although the data and observed flow physics might be different, the parametric effects and trends in microgravity are similar to vertical upflow in Earth gravity. Some cases, especially low mass velocities, high heat fluxes, and large degrees of inlet subcooling, experienced temporally anomalous flow behaviors caused by two-phase flow instabilities manifesting as flow reversals and resulted in deviations in overall trends. Severe thermodynamic non-equilibrium is observed throughout the channel. Overall, FBCE's ISS experiments were successful for subcooled inlet with single-sided heating of rectangular channel, and the collected data well established the various effects on flow boiling physics in highly controlled long-term microgravity conditions.

Robust validation of a generalised actuator disk CFD model for tidal turbine analysis using the FloWave ocean energy research facility

Coupled blade element momentum-computational fluid dynamic (BEM-CFD) approaches have been extensively used to study tidal stream turbine performance and wake development. These approaches have shown to be accurate when compared to tests conducted in tow-tanks or in regulated flumes with uniform flows across the turbine. Whilst such studies can be very useful, it is questionable as to what extent the results would differ in a larger scale environment where the flow is more representative of real-world conditions, being either unsteady or non-uniform. In this work, the effectiveness of a generalised actuator disk-computational fluid dynamics (GAD-CFD) approach in accurately capturing fluid-machine interaction for single and multiple tidal energy converters models is further assessed. A unique large-scale experimental facility, FloWave, has been used to conduct physical testing of three instrumented model tidal energy converters of rotor diameter 1.2 m under differing turbine layouts and realistic scaled environmental conditions. These large-scale tests provide a unique dataset against which this work's numerical simulations have been extensively validated. Comparisons between the tank and GAD-CFD approach show good agreement, particularly when comparing modelled to measured thrust, and enabled an evaluation of the effects of turbine spacing and arrangement on turbine performance and flow-field response.

Ecosystem effects of environmental extremes.

A large-scale experimental facility reveals tropical rainforest responses to drought.

Electron gun and collector for RAON EBIS charge breeder

A heavy-ion accelerator facility, called RAON, is being constructed in Korea. RAON is a large scale experimental facility for basic science research through nuclear physics experiments using various rare-isotope (RI) beams. An Electron Beam Ion Source (EBIS) will be utilized as a charge breeder in the isotope separation on-line (ISOL) system of RAON. The electron gun (e-gun) and electron collector are essential components of the EBIS to charge-breed the RI beams. The e-gun, a magnetically immersed type, has been designed to generate electron beams with currents up to 3 A. The material of the cathode is IrCe, which provide a higher current density and longer lifetime than the LaB6 cathodes. In addition, the collector which can dissipate electron beam power up to 20 kW has been designed and built. A test bench has been designed and constructed to commission the e-gun and collector sub-systems. The test bench is equipped with a negative high-voltage platform, called a cathode platform, to provide an independent electron beam current loop. The control system was also designed and implemented to be able to control two different platforms, such as the cathode and ground platforms, using the NI LabVIEW hardware and software. The experimental goals of the tests described in this paper are to generate and transport to collector 2 A electron beam, and to demonstrate a stable operation mode with electron beam width of 50 ms and a repetition rate of 10 Hz. These goals have been determined for the first charge breeding experiment, which is to obtain the charge-bred beam of Cs33+, in the future. This paper presents the electron gun and collector sub-system of RAON EBIS, including the cathode tests, the simulation results, and the electron beam experiment.

Large scale experimental facility for performance assessment of the vacuum vessel pressure suppression system of ITER

The nuclear fusion reactor ITER (International Thermonuclear Experimental Reactor) foresees a Pressure Suppression System (PSS) in order to manage a Loss of Coolant Accident (LOCA) in the Vacuum Vessel (VV). A LOCA scenario is postulated to occur in the cooling systems of plasma facing components. The Vacuum Vessel Pressure Suppression System (VVPSS) has a key safety function because a large internal pressure in the VV could lead to a breach of the primary confinement barrier.Steam condensation would occur in ITER at sub-atmospheric pressure, differently than the applications in nuclear fission reactors. Steam direct contact condensation (DCC) in sub-atmospheric conditions have never been implemented before, therefore an experimental assessment of the VVPSS is necessary to simulate this phenomenon in ITER's thermal-hydraulic conditions.Under the financial support of ITER Organization, an experimental program was performed at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa in the past 3 years, using a small-scale experimental rig (1/22 scale factor).In order to assess the scale laws elaborated by means of the experimental results obtained in this small scale facility, a Large Scale facility was built at University of Pisa. This facility is almost a full scale mock-up of ITER's VVPSS from the geometric point of view (1/1.09 scale factor) and it is 1/10 scale factor from the steam mass flow rate point of view.This paper illustrates the results of the first test campaign. A 1/10 scale sparger system SPS-A (having a diameter equal to DN125 and 100 holes) was used with a maximum steam mass flow rate of 0.5 kg/s. This experimental configuration represents real operating conditions on the basis of the results of elaborated similitude analysis. The preliminary analysis of the experimental results confirms the agreement in terms of condensation regimes between the two reduced scale (1/22 and 1/10 scale) as foreseen by the elaborated scale laws.

A full-scale experimental study of sub-slab pressure fields induced by underground perforated pipes as a soil depressurisation technique in radon mitigation

Sub-slab depressurisation systems have proven to effectively mitigate radon entry. A poor understanding of the fluid physics underlying the technique has been shown to lower the success rate substantially. This article describes a study of pressure fields in a sub-slab gravel bed induced by a soil depressurisation system consisting of perforated pipes run under the slab at a depth of 75 cm. The advantage of the approach is that pipes can be laid from outside the building to be protected. The study was conducted on a large-scale experimental facility where the variations in morphology and scope of pressure fields with different pipe combinations could be monitored and characterised. The findings showed that pressure was uniform across the entire area in the gravel bed, whereas the sensors buried in natural soil showed pressure to depend on distance from the source. Pressure transfer to the sub-slab plane was also observed to vary depending on the active pipe. Air-flow resistance studies in the layers of soil lying between the pipes and the gravel delivered different results for each pipe. That finding would appear to be related to the presence of preferential pathways in some parts of the soil. Total pressure when several pipes were activated was observed to be practically the same as the sum of the pressures transferred by each when working separately. The correlation between extraction fan power and pressure generated was also analysed. These and other factors are discussed and analysed from a perspective of the understanding of such highly effective techniques.

Ventilation schemes for high-temperature buoyancy-driven plumes from spherical surfaces of a large-scale experimental facility

Abstract A large-scale sphere-shaped experimental facility for neutrino detection is designed as a 23-latitudinal layer composite by using organic glass as the major raw material and is assembled via mass polymerization through a top-to-bottom approach. Heating belts at 4200 W/m2 are used to anneal the bonding joints of external and internal spherical surfaces and produce high-temperature thermal plumes. Buoyancy-driven plumes should be effectively mitigated using ventilation to ensure the near-surface air temperatures above the finished layers can be delicately controlled within 21±1 °C to minimize the deformation of the facility. Schemes to control plumes on both surfaces were investigated using Computational Fluid Dynamics (CFD) method by following a performance-based approach. First, an independent field study was conducted to measure surface temperature and heat flux of mass polymerization and provide references for simulations. Second, dynamic buoyancy-driven plumes produced along the external and internal spherical surfaces were simulated under a no-ventilation scenario. After contacting with the plumes, three periods, in which buoyancy, convection, and advection, were dominating, can be observed according to the changes of near-surface air temperature. Moreover, the temperature and Ra number of the surface-attached plumes were used as indicators to assess the intensity of the plumes quantitatively. Third, three major ventilation schemes, i.e., general, push-pull, and sphere-attached ventilations (with three subdesigns), were compared under the same air change rate level on the basis of the following perspectives: (1) air temperature distributions above the polymerizing layer, (2) overall heat exhaust efficiency, and (3) total spaces where temperature was higher than 22 °C. Results indicated that the combination of push-pull and side-supply ventilations, by which the heat exhaust efficiencies were up to 1.87–3.24, was found to be most effective to control thermal plumes, with approximately 0.1% of the total surrounding air exceeding 22 °C.

CABARET scheme for modelling the stratification erosion in gas mixtures in hydrogen mitigation experiments for reactor safety

Experiments on atmosphere mixing and stratification in the large scale experimental facility (PANDA), where the initial helium stratification in a vessel is eroded by a vertical jet of steam, were simulated with the CABARET scheme. Good agreement between calculated and measured gas temperature and concentrations has been achieved by refining the mesh and adding the model of radiative heat transfer. The simulation results are presented and discussed.

Mathematical modelling of hydrogen safety problems with CABARET scheme

Experiments on overall fluid transfer and mixing in the large scale experimental facility (PANDA), where the initial helium-rich layer is eroded by a flow resulting from the interaction of a jet/plume with horizontal flow obstruction, were simulated with the CABARET scheme. Computational simulation results are provided for two mesh resolutions and are compared with the experimental data. Good agreement between calculated and measured gas temperature and the breakup of the helium layer dynamics was achieved by refining the mesh in the jet area and by adding the model of radiation heat transfer.

Predicting Severe Slugging in Toe-Down Horizontal Wells

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191611, “Existence and Prediction of Severe Slugging in Toe-Down Horizontal Wells,” by Jayanth Nair, SPE, Eduardo Pereyra, SPE, and Cem Sarica, SPE, The University of Tulsa, prepared for the 2018 SPE Annual Technical Conference and Exhibition, Dallas, 24–26 September. The paper has not been peer reviewed. Severe slugging is an important flow-assurance issue, typically observed in offshore pipeline-riser systems. The consequences of severe slugging include flooding of downstream production facilities and an overall decrease in productivity. Severe slugging had been thought to be limited to systems with a downward-inclined pipeline and vertical, catenary, or lazy-S-shaped riser. This paper presents the results of an experimental and modeling study that demonstrates the existence of severe slugging in systems with upward-inclined lateral flow paths, such as a toe-down well. Introduction Severe slugging in offshore pipeline-riser systems with downward-inclined pipelines has been intensely studied because of its serious consequences. Most such studies are related to pipeline-riser systems, but the possibility of severe slugging in toe-up horizontal wells also was demonstrated experimentally in the literature. Toe-up wells are geometrically analogous to pipeline-riser systems because the lateral section in a toe-up well is a mostly downward-inclined flow path. However, there has been no documented evidence of severe slugging in systems with upward-inclined flow paths.• Facility Description A large-scale experimental facility was used in this study. This facility was designed primarily to study flow behavior in horizontal wells. The lateral section in the facility was 236 ft long and comprised 6-in. inner-diameter (ID) pipe, which acted as the casing. The curvature section was made of bent acrylic pipe and had a radius of curvature of approximately 18 ft. The vertical section was 34 ft high with 2-in. ID polycarbonate pipe simulating the tubing. The schematic shows a packerless configuration. In such a configuration, an additional volume was necessary to simulate the effect of an annular volume. This was achieved by adding a 37-ft-high, 6-in.-ID expansion volume. For cases where a packer was required, a solid plug was placed in the system to simulate the packer and the annular volume was disconnected. The end of the tubing location was varied by pulling the tubing or running the tubing deeper. The test fluids were air and water. Air and water entered the facility at the toe of the well. The mass flow rates were measured using flowmeters and were held constant during the tests. As the flow pattern developed along the lateral section, flowing pressures, temperatures, and pressure gradient were measured. Conductivity probes allowed the measurement of slug characteristics. The test facility also included several quick-closing valves. These valves were pneumatically operated and could capture the flow and measure holdup. When the flow reached the top of the vertical section, it returned to the water tank where the air was vented. A separate metering skid was used to inject gas in the tubing to study the effect of gas lift.

Technology Focus: Flow Assurance

Technology Focus Flow assurance and multiphase-flow design, engineering, operations, and maintenance technical concerns have presented interesting and challenging issues requiring safe, economical solutions over my 20+ years of project experience around the world in both onshore unconventional and offshore conventional production facilities as an engineering, procurement, and construction contractor; major operator; manufacturer; and consultant. While gas-hydrate prediction and handling typically dominates the thermohydraulic design, the subsequent long-term mitigation of slugging and various flow-assurance phenomena, along with prevention of wax, erosion, asphaltenes, corrosion, and salt deposition, are all challenging issues.• First, severe slugging, frequently observed in pipeline and riser systems, is an important flow-assurance issue. The consequences of slugging usually involve flooding of downstream pipeline and production facilities and an overall decrease in field and system productivity. On the basis of experimental observations, severe slugging prediction models were developed and verified. Second, regular intervention activities to improve flow assurance, such as frequent pigging and injection of chemical inhibitors or drag-reducing agents, all require operational expense and require safety oversight and downtime. Internal pipeline coatings and liners are available solutions that could provide long-term benefits. Third, access to real-time production data on a desktop computer could improve an operations/pipeline engineer’s efficiency and system performance greatly. A smart management system is described that is capable of retrieving and evaluating flow-assurance-related data from multiple wells. This system can allow the operator to make better-informed decisions on the basis of a consistent data set with less time spent gathering and analyzing the data. The papers presented here discuss slightly different issues and approaches to multiphase flow continuity and production flow assurance. Severe slugging consequences typically include flooding of pipeline and production facilities and a subsequent decrease in production rate. Such severe slugging was previously thought to be limited to systems with upward, inclined pipeline or vertical, catenary or lazy-S-shaped risers. However, paper SPE 191611 presents the results of an experimental and modeling study that demonstrates the existence of severe slugging in systems with upward, inclined lateral flow paths such as a toe-down well, similar to that observed in a large-scale experimental facility specially constructed for studying flow behavior in horizontal wells.••• Pipeline internal deposits, such as corrosion and scale, can reduce the flow efficiency and design capacity of a transport system greatly. The use of interior pipeline coatings and liners is a potential long-term design solution that could provide long-term refurbishment benefits. The work described in paper SPE 193109 involves a novel material designed to interact specifically with highly corroded and weathered pipe, thus enabling in-place application and refurbishment.•••••• Paper SPE 191951 describes a smart management system used for retrieving and evaluating all flow-assurance-related data for more than 700 wells in both onshore and offshore fields. The paper discusses system architecture, interface details, system design, functionality, visualization, application, and the benefits of the system.• The papers presented here, including the additional reading papers on the potential novel applications of subsea tieback technology, focus on developing new analytical tools and new materials while providing safe, cost-effective, and reliable operations for flow assurance. I hope you find them as interesting as I did, and I greatly appreciate this opportunity to disseminate these new technology options to you in this and future Technology Focus sections. In addition, I invite you to join the Flow Assurance Technical Section. Recommended additional reading at OnePetro: www.onepetro.org. SPE 191748 Single-Flowline Tiebacks: Flow-Assurance Considerations From Appraisal to Operations by Juan I. Monge, Gate Energy, et al. OTC 29232 Real-Time Subsea Hydrate Management in the World’s Longest Subsea Tieback by Christophe Vielliard, OneSubsea, et al. OTC 29319 Subsea Long-Distance Tieback by Douglas Peter Wiles, TechnipFMC, et al.

Optimal operation of oil and gas production using simple feedback control structures

The purpose of this paper is to describe the control challenges related to optimal operation of oil and gas production wells, and show that optimal operation can be achieved using simple feedback control structures. In particular, we find that conventional feedback control structures can efficiently handle changes in active constraint regions using simple logics such as split-range and selectors. This eliminates the need for complex models to be used in the optimization problem, and in addition eliminates the need to solve numerical optimization problems online. Thus, by using only simple feedback controllers that have been used widely in the oil and gas industry, it has a higher chance of implementation. We demonstrate the use of simple feedback controllers on two application examples; 1) a gas-lift optimization simulation study with a network of six gas-lifted wells, 2) an experimental study of optimal control of electrical submersible pump (ESP) lifted oil wells tested on a large-scale experimental test facility with a full scale ESP and live viscous crude oil.

The role of CFD combustion modeling in hydrogen safety management – VII: Validation for hydrogen deflagration in large-scale hydrogen-air-steam experiment

Abstract A postulated severe accident in a nuclear power plant (NPP) can lead to generation of large quantities of hydrogen in the NPP containment. Potential hydrogen combustion and ensuing dynamic pressure loads can be detrimental to the integrity of the containment and its structure, systems and components. This paper provides validation results of a computational fluid dynamics (CFD) modeling approach based on two combustion models, that is the Turbulent Flame-speed Closure (TFC) model and the Extended TFC (ETFC) model. The latter was further elaborated in order to investigate the influence of the laminar flame speed on the flame evolution and propagation modeling. As a result, a newly developed approach in form of the augmented ETFC model was introduced and validated as well. The hydrogen slow deflagration results from the Upward Flame Propagation Experiment (UFPE) conducted in the large-scale HYKA-A2 experimental facility have been used for validation. The main results of the performed validation are presented and discussed, with the focus on axial and radial flame front propagation, maximum pressure, pressure increase rate and flame front development.

Observation of turbulence and intermittency in wave-induced oscillatory flows

The dynamic and thermal regimes of the climate are regulated by an exchange of energy and momentum between the atmosphere and the ocean. The role exerted by surface waves on this interchange is particularly enigmatic. Waves induce turbulence in the upper ocean by breaking and through Langmuir circulations. However, there is evidence that the wave oscillatory flow can be turbulent and directly inject mixing into subsurface layers. The existence, extent and properties of this non-breaking, wave-induced turbulent flow still remain uncertain. Here we present measurements of the velocity field of oscillatory flows, which are induced by mechanically generated random wave fields in a large scale experimental facility. Velocities were recorded at a depth sufficiently far from the water surface to rule out the effects of wave breaking. We demonstrate that the spectral tail of the velocity field follows a power-law scaling close to ω−5∕3, with ω being the radial frequency. The turbulent behaviour is investigated via rigorous statistical analysis of the structure functions to highlight the emergence of intermittency in oscillatory flows.

Options for refractive index and viscosity matching to study variable density flows

Variable density flows are often studied by mixing two miscible aqueous solutions of different densities. To perform optical diagnostics in such environments, the refractive index of the fluids must be matched, which can be achieved by carefully choosing the two solutes and the concentration of the solutions. To separate the effects of buoyancy forces and viscosity variations, it is desirable to match the viscosity of the two solutions in addition to their refractive index. In this manuscript, several pairs of index matched fluids are compared in terms of viscosity matching, monetary cost, and practical use. Two fluid pairs are studied in detail, with two aqueous solutions (binary solutions of water and a salt or alcohol) mixed into a ternary solution. In each case: an aqueous solution of isopropanol mixed with an aqueous solution of sodium chloride (NaCl) and an aqueous solution of glycerol mixed with an aqueous solution of sodium sulfate ( $$\hbox {Na}_2\hbox {SO}_4$$ ). The first fluid pair allows reaching high-density differences at low cost, but brings a large difference in dynamic viscosity. The second allows matching dynamic viscosity and refractive index simultaneously, at reasonable cost. For each of these four solutes, the density, kinematic viscosity, and refractive index are measured versus concentration and temperature, as well as wavelength for the refractive index. To investigate non-linear effects when two index-matched, binary solutions are mixed, the ternary solutions formed are also analyzed. Results show that density and refractive index follow a linear variation with concentration. However, the viscosity of the isopropanol and NaCl pair deviates from the linear law and has to be considered. Empirical correlations and their coefficients are given to create index-matched fluids at a chosen temperature and wavelength. Finally, the effectiveness of the refractive index matching is illustrated with particle image velocimetry measurements performed for a buoyant jet in a linearly stratified environment. The creation of the index-matched solutions and linear stratification in a large-scale experimental facility are detailed, as well as the practical challenges to obtain precise refractive index matching.

Safest Roadmap for Corium Experimental Research in Europe

Severe accident facilities for European safety targets (SAFEST) is a European project networking the European experimental laboratories focused on the investigation of a nuclear power plant (NPP) severe accident (SA) with reactor core melting and formation of hazardous material system known as corium. The main objective of the project is to establish coordinated activities, enabling the development of a common vision and severe accident research roadmaps for the next years, and of the management structure to achieve these goals. In this frame, a European roadmap on severe accident experimental research has been developed to define research challenges to contribute to further reinforcement of Gen II and III NPP safety. The roadmap takes into account different SA phenomena and issues identified and prioritized in the analyses of severe accidents at commercial NPPs and in the results of the recent European stress tests carried out after the Fukushima accident. Nineteen relevant issues related to reactor core meltdown accidents have been selected during these efforts. These issues have been compared to a survey of the European SA research experimental facilities and corium analysis laboratories. Finally, the coherence between European infrastructures and R&D needs has been assessed and a table linking issues and infrastructures has been derived. The comparison shows certain important lacks in SA research infrastructures in Europe, especially in the domains of core late reflooding impact on source term, reactor pressure vessel failure and molten core release modes, spent fuel pool (SFP) accidents, as well as the need for a large-scale experimental facility operating with up to 500 kg of chemically prototypic corium melt.

Tsunami evolution and run-up in a large scale experimental facility

In this paper, we study the propagation and run-up of long tsunami-like waves in the 300m long Large Wave Flume (GWK), Hannover, Germany and analyze the feasibility of experiments on tsunami run-up in large facilities. This paper is the continuation of our previous paper (Schimmels et al., 2015, companion paper). The propagation of long period waves over large distances for different shapes is studied experimentally and numerically. Fully nonlinear potential flow theory has been used to model these cases numerically along with Korteweg–de Vries simulations. The theoretical explanation of the observed effects has been discussed. The run-up characteristics of the studied waves with respect to their shape and beach slope were also investigated. Further, a downscaled real tsunami time series is also reproduced experimentally and studied with regard to its possible run-up.

Tsunami generation in a large scale experimental facility

Experimental studies on tsunami are carried out since many years, most of them by generating solitary waves with a piston type wave maker. However, today it is more and more appreciated that these kinds of waves actually do not represent a real tsunami very well, as particularly for the shallow waters at the coast the wave length becomes comparably far too short. Recently new generation methods for scaled down real tsunami experiments were suggested, as it was doubted that sufficiently long waves could be generated with a classical wave maker. The present paper shall disprove these arguments by providing results of a study carried out in the Large Wave Flume (Großer Wellenkanal, GWK), where waves of periods between 30s and more than 100s at 1m water depth were successfully generated with a piston type wave maker. Results for elongated solitary waves, trough led N-waves and real tsunami records as a combination of a different number of general solitons (sech2 waves) are presented. Finally, the requirements and limitations to bring a “real” tsunami into the laboratory are discussed.