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The interplay between seismic activity and fluid flow is essential during the evolution of hydrothermal systems. Although earthquakes can trigger transient fluid flow and phase changes in dilational jogs, the temporal scale and the geologic conditions that enhance such process are poorly quantified. Here, we use numerical simulations of deformation and fluid flow to constrain the conditions that maximize adiabatic boiling—referred to as flashing—and estimate the extent and duration of such process. We show that there is an optimal geometry for a dilational jog that maximizes co‐seismic flashing within the jog. Fluid flow simulations indicate that the duration, intensity, and propagation of the flashing front are limited and highly dependent on the magnitude of the co‐seismic slip and the initial pressure‐enthalpy conditions. Our results are valuable to better understand the implications of pressure fluctuations during the seismogenic cycle, as well the mineralization processes in the Earth's crust. Plain Language Summary: Earthquakes can strongly affect circulating fluids within the Earth's crust, mainly where faults bend or split into different fault segments and produce dilatant areas. In these areas, earthquakes play an important role in forming ore deposits, because the co‐seismic volume change can produce a pressure drop that drives boiling with gas exsolution and subsequent mineralization. This process, in which boiling is triggered by a pressure drop rather than a temperature rise, is called flash vapourization or flashing. Here, we used a computer code to unravel scenarios where optimal geometry and pressure‐temperature conditions maximize flash vapourization. Furthermore, we found that the duration and extension of the flashing event are limited and highly dependent on the magnitude of the triggering earthquake and the physico‐chemical conditions of the system. Such results are valuable for assessing the implications of pressure fluctuations during the seismogenic cycle and for better understanding mineralization processes in the Earth's crust. Key Points: We use numerical simulations to constrain the intensity and temporal scale of co‐seismic flash vapourization or flashing triggered by earthquakesWe found an optimal geometry of a dilational jog that maximizes co‐seismic flashing within the jogsUnder optimal conditions, the flashing front propagates up to 1 m away from the dilational jog and persists for almost 3 hr [ABSTRACT FROM AUTHOR]

Some parasites manipulate their hosts phenotype to enhance predation rates by the next host in the parasites life cycle. Our understanding of this parasite-increased trophic transmission is often stymied by study-design challenges. A recurring difficulty has been obtaining uninfected hosts with a coevolutionary history with the parasites, and conducting experimental infections that mimic natural processes. In 1996, Lafferty and Morris provided what has become a classic example of parasite-increased trophic transmission; they reported a positive association between the intensity of a brain-infecting trematode (Euhaplorchis californiensis) in naturally infected California killifish (Fundulus parvipinnis) and the frequency of conspicuous behaviors, which was thought to explain the documented 10-30× increase in predation by the final host birds. Here, we address the primary gap in that study by using experimental infections to assess the causality of E. californiensis infection for increased conspicuous behaviors in F. parvipinnis. We hatched and reared uninfected F. parvipinnis from a population co-occurring with E. californiensis, and infected them 1-2 times/week over half their life span with E. californiensis and a small cyathocotylid trematode (SMCY) that targets the hosts muscle tissue. At 3 time points throughout the hosts lives, we quantified several conspicuous behaviors: contorting, darting, scratching, surfacing, and vertical positioning relative to the waters surface. Euhaplorchis californiensis and SMCY infection caused 1.8- and 2.5-fold overall increases in conspicuous behaviors, respectively. Each parasite was also associated with increases in specific conspicuous behaviors, particularly 1.9- and 1.4-fold more darting. These experimental findings help solidify E. californiensis-F. parvipinnis as a classic example of behavioral manipulation. Yet our findings for E. californiensis infection-induced behavioral change were less consistent and strong than those previously documented. We discuss potential explanations for this discrepancy, particularly the idea that behavioral manipulation may be most apparent when fish are actively attacked by predators. Our findings concerning the other studied trematode species, SMCY, highlight that trophically transmitted parasites infecting various host tissues are known to be associated with conspicuous behaviors, reinforcing calls for research examining how communities of trophically transmitted parasites influence host behavior.

Abstract The interplay between seismic activity and fluid flow is essential during the evolution of hydrothermal systems. Although earthquakes can trigger transient fluid flow and phase changes in dilational jogs, the temporal scale and the geologic conditions that enhance such process are poorly quantified. Here, we use numerical simulations of deformation and fluid flow to constrain the conditions that maximize adiabatic boiling—referred to as flashing—and estimate the extent and duration of such process. We show that there is an optimal geometry for a dilational jog that maximizes co‐seismic flashing within the jog. Fluid flow simulations indicate that the duration, intensity, and propagation of the flashing front are limited and highly dependent on the magnitude of the co‐seismic slip and the initial pressure‐enthalpy conditions. Our results are valuable to better understand the implications of pressure fluctuations during the seismogenic cycle, as well the mineralization processes in the Earth's crust.

To address the issue of erosion in the control valves of blackwater flash systems in the coal chemical industry, this study investigates the dynamic erosion characteristics of one such control valve. Computational fluid dynamics is employed to compare the results obtained with a static mesh and an erosion-coupled dynamic mesh, and the valve erosion is investigated by analyzing the erosion rate, the particle impact velocity, trajectories and angle. Moreover, the relationship between the deformation caused by erosion and the dispersion of the flash vapor phase in the valve is studied, focusing on the flow resistance coefficient. The results indicate that over a period of 9 × 106 s, the impact velocity and subsequent collisions of particles reduce, and the impact angle decreases with the accumulated deformation of the valve core. Notably, the valve core is influenced primarily by the cutting that results from low impact angles, leading to a substantial decrease in the overall erosion rate of the valve, amounting to a reduction of 56.4%. The region facing the flow is at significant risk of erosion, and as the opening decreases, the erosion zone extends gradually to the annular region of the valve core and valve head, leading to increased erosion deformation. Furthermore, as the flow resistance coefficient decreases, so does the vapor volume fraction inside the valve. This study provides a theoretical basis for predicting faults and developing online monitoring solutions for high-differential-pressure control valves in blackwater flashing systems.

To address the issue of erosion in the control valves of blackwater flash systems in the coal chemical industry, this study investigates the dynamic erosion characteristics of one such control valve. Computational fluid dynamics is employed to compare the results obtained with a static mesh and an erosioncoupled dynamic mesh, and the valve erosion is investigated by analyzing the erosion rate, the particle impact velocity, trajectories and angle. Moreover, the relationship between the deformation caused by erosion and the dispersion of the flash vapor phase in the valve is studied, focusing on the flow resistance coefficient. The results indicate that over a period of 9 Ã--106 s, the impact velocity and subsequent collisions of particles reduce, and the impact angle decreases with the accumulated deformation of the valve core. Notably, the valve core is influenced primarily by the cutting that results from low impact angles, leading to a substantial decrease in the overall erosion rate of the valve, amounting to a reduction of 56.4%. The region facing the flow is at significant risk of erosion, and as the opening decreases, the erosion zone extends gradually to the annular region of the valve core and valve head, leading to increased erosion deformation. Furthermore, as the flow resistance coefficient decreases, so does the vapor volume fraction inside the valve. This study provides a theoretical basis for predicting faults and developing online monitoring solutions for high-differential-pressure control valves in blackwater flashing systems. [ABSTRACT FROM AUTHOR]

PT X Indonesia is one of the Korean Foreign Manufacturing Companies (PMA) that produce injection molding. December 2022 PT X Indonesia received customer complaints from PT. Y because of defects in products such as: gas burn, white spot, weld line, bending, short shoot, bubbles, flashing, silver, wrong color, and contamination. Flashing is a type of defect that the largest number of ratios reaches 10% while the defect restriction of the customer is 2% so the company and the authors choose the theme of improvement in 2018 is the improvement of molding design to reduce flashing defects in plastic products. The method used in the proposed improvement of molding design is the taguchi method by making 4 point suggestion that is the level 1 slot dimension: Hight 70mm taper 15 °, level 2: Hight 70mm taper 10 °, level 3: High 70mm taper 5 °; insert level 1 dimension: 70mm taper insert 1 °, level 2: 70mm taper deepness insert 2 °, level 3: 70mm taper deepth insert 3 °; clamping tolerance force level 1: + 5%, level 2: + 8%, level 3: + 10% and parting line line length 1: 10mm, level 2: 20mm, level 3: 30mm. The proposed best molding design improvements are in Slast dimensions: Hight 70 mm taper 15 °, Insert: 70mm taper deepness 2 °, clamping force tolerance + 10%, Parting Line Length: 30mm. The smallest flashing flaw was found to be 0.1% in confirmatory experimental conditions, much smaller than the specified target defects of 2%. Cost reduction cost obtained by PT ART Mold Indonesia with the proposed repair on Molding design that is Rp 115.600.000,00 per 1 molding. The cost savings incurred by customers of PT ART Mold Indonesia is worth Rp 784.080.000,00 per year

The Two-Fluid Model (TFM) has long been the backbone of engineering-scale two-phase flow simulation in system-analysis codes and computational fluid dynamics codes. The classical TFM is limited in how it can capture the differences in the transport of small and large bubbles. The two-group TFM provides the ability to specify the unique transport characteristics of small and large bubbles separately. Expanding to two sets of conservation equations for the two bubble groups presents the additional challenge of bubble group accounting as bubbles can cross the group boundary. The three mass transfer terms in the two-group TFM are evaluated for flashing, condensing, and boiling flows using a partitioning method. The axial trends in the source terms are examined for these flow conditions with the available intergroup models. Two-group interphase models are implemented and evaluated against experimental data for flashing, condensing, and boiling flows with accurate two-group results. The capabilities of the two-group TFM are evaluated for these flow types, demonstrating the ability to predict two-group vapor properties without the need for flow regime transitions. [ABSTRACT FROM AUTHOR]

Quartz veins in bonanza-type ore zones of low-sulfidation epithermal deposits frequently contain ore mineral dendrites. Gold and naumannite dendrites hosted by colloform silica bands from four deposits located in California and Nevada were studied to better understand the processes by which these delicate ore mineral aggregates are formed. High-magnification optical petrography revealed that the colloform bands hosting the ore mineral dendrites originally consisted of non-crystalline silica microspheres. Textural relationships suggest that the microspherical silica provided the structural framework for the delicate ore mineral aggregates to grow. The ore mineral dendrites either grew contemporaneously with the deposition of the microspherical silica along the vein walls or after their deposition within permeable gel-like layers of microspheres. Etching in hydrofluoric acid showed that the ore mineral dendrites exhibit complex surface morphologies. The surface morphology of the ore mineral dendrites and their textural relationships with the silica host were modified as a result of post-depositional maturation and recrystallization causing the conversion of the non-crystalline silica to quartz. It is proposed here that ore mineral dendrites formed in low-sulfidation epithermal veins during periods of two-phase flow associated with short-lived events of vigorous boiling or flashing, which caused supersaturation of silica in the liquid and the deposition of the ore minerals. [ABSTRACT FROM AUTHOR]

For the development of upper stage rocket engines with laser ignition, the transition of oxidizer and fuel from the pure cryogenic liquid streams to an ignitable mixture needs to be better understood. Due to the near vacuum conditions that are present at high altitudes and in space, the injected fuel rapidly atomizes in a so-called flash boiling process. To investigate the behavior of flashing cryogenic jets under the relevant conditions, experiments of liquid nitrogen have been performed at the DLR Lampoldshausen. The experiments are accompanied by a series of computer simulations and here we use a highly resolved LES to identify 3D effects and to better interpret results from the experiments and existing 2D RANS. It is observed that the vapor generation inside the injector and the evolution of the spray in the combustion chamber differ significantly between the two simulation types due to missing 3D effects and the difference in resolution of turbulent structures. Still, the observed 3D spray dynamics suggest a suitable location for laser ignition that could be found in regions of relative low velocity and therefore expected low strain rates. Further, measured droplet velocities are compared to the velocities of notional Lagrangian particles with similar inertia as the measured droplets. Good agreement between experiments and simulations exists and strong correlation between droplet size and velocity can be demonstrated. [ABSTRACT FROM AUTHOR]

Natural circulation is employed in new designs of light water reactors to enhance passive safety by maintaining flow and heat removal without pumps. Under low-pressure and low-flow-rate conditions, natural circulation is susceptible to two-phase instabilities leading to undesirable flow oscillations and operational difficulties. Flashing instability is one of the most widely reported low-pressure natural circulation instabilities, related to saturated vaporization triggered by a hydrostatic pressure drop in an adiabatic riser above a heated section. While existing studies have reported flashing instability experiments, modeling, and simulations including successes in matching numerical results and experimental data, solid yet clear analytical explanations for many of its qualitative features are still rare. To enhance the physical understanding beyond stability boundary prediction, the current work develops, validates, and analyzes a linear stability model of flashing instability. This model adopts a one-dimensional Drift-Flux Model simplified by physical assumptions and approximations, and it includes optional component models to match an actual facility for validation. Stability tests are performed on a 5-m-tall natural circulation loop, providing comprehensive benchmark data covering stability boundaries, one-dimensional transient signals, and periodic mean waveforms from local measurements. Validation confirms acceptable predictions of steady states, stability boundaries, and oscillation periods. The tractable model formulation leads to a closed-form characteristic function facilitating analytical manipulations and physical interpretations, based on which dominant pressure drop responses to inlet flow rate are extracted. The major instability mechanism is identified as a strong response of the two-phase driving force to the inlet flow rate that is delayed by enthalpy transportation through a long single-phase distance and can become an overwhelmingly destabilizing positive feedback under low-frequency perturbations. Experimentally reported qualitative features, including stability changes, timescale relations, and oscillation patterns, are analytically predicted and physically explained with clarity. In general, this study enriches experimental resources of flashing instability with a comprehensive dataset and provides a simple yet realistic analytical basis for physically understanding flashing instability beyond predicting stability boundaries. [ABSTRACT FROM AUTHOR]

The development of phase change models applicable to a wide range of temperatures, pressures, and mass flow rates is primarily limited by the metastable or partially stable behaviour of the fluid. Due to this, the fluid does not change phase even after crossing saturation conditions. Most liquid–vapour phase change models have been developed primarily for the cavitation process where the phase change is not sustained, occurs in a very narrow region of space, or occurs under equilibrium conditions. In this paper, the mechanism of phase change is discussed along with the review of three different computational fluid dynamics (CFD)‐based phase change methods available in OpenFOAM, which are used to simulate flashing of steam, in applications related to steam assisted gravity drainage (SAGD) systems. The first method is based on barotropic compressibility (BC) used with the realizable k−ε turbulence model, the second combination is of mass transfer model (MTM) with the realizable k−ε turbulence model, and the third one is based on two fluid (TF) method along with a family of k−ω turbulence models. These methods are tested on a converging–diverging nozzle with pressure driven phase change. It is demonstrated that these methods are not able to adjust their physics to different depressurization rates, do not account for liquid to be in superheated conditions, and have significant discrepancies with experimental results. In the end, better approaches to model this category of phase change are discussed. [ABSTRACT FROM AUTHOR]

The article presents the results obtained from a complex study of heavily superheated water atomization during its discharging through various types of atomizers. A system for optic measurements of the spray cone dispersion structure has been developed and adjusted. The developed measurement system is based on measuring the scattering indicatrix of a probing laser emission in a wide range of angles (±45°) and solving the inverse scattering problem using the Mie theory. The results from a wide-scale experimental study of the spray cone dispersion structures produced by various types of nozzles with a sprayed water temperature of 140‒260°С and pressure at the nozzle exit equal to 0.1 MPa are presented, and the possibility of liquid atomization (to water droplets with a diameter of 5 µm or smaller down to submicrometer size) at high temperatures is shown. It has been found that the spray cone structure has a pronounced bimodal pattern: droplets 5‒8 µm in diameter combine with a submicrometer mode. With a growth of atomized water temperature, the fraction of submicrometer mode increases, reaching 60‒65 wt % at a temperature of 240‒260°С for cylindrical nozzles and 80‒90 wt % for convergent-divergent nozzles. For the case of water injection into the compressor of a gas turbine unit equipped with the TV-117 industrial grade turbine, the possibility of additionally controlling the peak power output has been demonstrated. It makes 4–8% per water flowrate percent (with respect to the air flowrate). The power output control quality is in compliance with the requirements of the UES of Russia network standards. Superheated water is finding an increasingly growing use for firefighting at power industry facilities, in closed premises, in spills of petroleum products, in performing operations with liquefied gas, and in other situations. [ABSTRACT FROM AUTHOR]

The CFD numerical study of the flash boiling phenomenon of a water film was conducted using an Euler–Euler method, and compared to the experiments on the flashing of a water film. The water film is initially heated at temperatures ranging from 34 to 74 ∘ C (frim 1 to 41 ∘ C superheat), and the pressure is decreased from 1 bar to 50 mbar during the experiments. This paper shows that the experiments could not be correctly modelled by a simple liquid/bubble model because of the overestimation of the drag force above the water film (in the gas/droplet region). The generalised large interface model (GLIM), however, a multi-regime approach implemented in the version 7.0 of the neptune_cfd software, is able to differentiate the water film, where liquid/bubble interactions are predominant from the gas region where gas/droplet interactions are predominant, and gives nice qualitative results. Finally, this paper shows that the interfacial heat transfer model of Berne for superheated liquids could accurately predict the evolution of the water temperature over time. [ABSTRACT FROM AUTHOR]

Expansion valves are among key components of air conditioners. A one-dimensional model has been developed with the maximum mass flow. Temperature difference across the valve might cause heat transfer and affect inlet subcooling. Heat conduction coefficient was modified based on experimental data to obtain reliable discharge rate predictions. [ABSTRACT FROM AUTHOR]

Experimental research on flow characteristics of open natural circulation system was performed, to figure out the mechanism of the open natural circulation behaviors. The influence factors, such as the heating power, the inlet subcooled and the level of cooling tank on the flow characteristics of the system were examined. It was shown that within the scope of the experimental conditions, there are five flow types: single-phase stable flow, flash and geyser coexisting unstable flow, flash stable flow, flash unstable flow, and flash and boiling coexisting unstable flow. The geyser flow in flash and geyser coexisting unstable flow is different from classic geysers flow. The flow oscillation period and amplitude of the former are more regular, is a newly discovered flow pattern. By drawing the flow instability boundary diagram and sorting out the flow types, it is found that the two-phase unstable flow is mainly characterized by boiling and flash, which determine the behavior of open natural circulation respectively or jointly. Moreover, compared with full liquid level system, non-full liquid level system is more prone to boiling phenomenon, and the range of heat flux density and undercooling degree corresponding to unstable flow is larger.

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In the context of growing calls for a new law criminalising cyberflashing – the digital distribution of penis images to another without consent – this article makes the case for a comprehensive, 'consent-based' criminal offence specifically targeting cyberflashing. It justifies this approach by examining the core wrongs of cyberflashing and suggests draft legislative text for such an offence. In making this case, the article analyses and rejects the Law Commission's recent proposal for a 'motive-based' cyberflashing law. Ultimately, it is argued that while the Law Commission's proposal is a welcome recognition of the harms of cyberflashing and need for reform, it does not go far enough to offer the redress victim-survivors are seeking, nor does it provide an appropriate normative foundation for education and preventative initiatives. [ABSTRACT FROM AUTHOR]

• Visual observation of two-phase mixture during flash evaporation. • Void fraction measurements using capacitance probe. • Correlation of data. Flashing is a pressure driven phase change phenomenon. It is widely studied due to its richness in physics and applications such as in desalination, in nuclear industry to name a few. Dynamic flashing is a situation wherein the pressure drop for flashing is initiated through the flow of liquid. A recently developed novel desalination system [ 1 ] utilizes combined dynamic flashing and vapor separation through tangential injection for producing potable water. An understanding of dynamic flashing in a tube with reference to the novel desalination system could help with its optimization. In this work, dynamic flashing of tap water occurring in a clear quartz square tube was studied. The pressure and temperature measurements along the tube were made and analyzed for different inlet flowrates and initial liquid temperatures. The pressure and temperature values showed increasing gradients along the tube indicating increased vapor production or flashing for increasing flowrates and initial liquid temperatures. The vapor production from flashing and the resulting flow regimes along the tube were tracked and identified through high-speed imaging. Visual observations showed complex flow regimes with bubbles nucleating and growing throughout the tube due to flashing. Most of the bubble formation was observed in the bulk with little nucleation on the glass tube wall. Void fraction measurements along the tube based on capacitance impedance technique were performed to supplement the visual observations which showed increasing void fraction along the tube matching the observed flow regimes from vapor production. [ABSTRACT FROM AUTHOR]

A great deal of research has examined the efficacy of variable message signs (VMS) to induce driver behavior changes, improve safety conditions, and decongest the traffic network. However, there is little literature regarding the most effective ways to display this information on VMS. Furthermore, none of the previous contributions have concentrated on analyzing what impact flashing VMS have on drivers by using real traffic data. This article seeks to bridge this gap, analyzing the effect of incorporating intermittent light stimulation to messages on drivers' behavior on a Chilean highway, using vehicle-by-vehicle data obtained in a non-intrusive way. In order to do so, an experiment was carried out to measure the responses of drivers when faced with two types of messages: (1) those intended to induce a speed reduction and (2) those aimed at generating lane changes. From the statistical models we obtained several insights. Our results show that flashing messages may increase the effectiveness of VMS depending on environmental and traffic conditions. In particular, for speed moderation messages, we found 12 significant effects, showing, for example, that a flashing message is most effective in the hours of darkness, with low congestion, small spacing, and low average speeds. Additionally, it has a more significant impact on experienced drivers. On the other hand, for lane change messages, we found five significant effects, showing that flashing messaging reduces its effectiveness in situations where a high cognitive load is required, such as in high flow and high average speeds. No particular effects were identified in either case for specific vehicle types. [ABSTRACT FROM AUTHOR]

The CFD numerical study of the flash boiling phenomenon of a water film was conducted using an Euler–Euler method, and compared to the experiments on the flashing of a water film. The water film is initially heated at temperatures ranging from 34 to 74 ∘C (frim 1 to 41 ∘C superheat), and the pressure is decreased from 1 bar to 50 mbar during the experiments. This paper shows that the experiments could not be correctly modelled by a simple liquid/bubble model because of the overestimation of the drag force above the water film (in the gas/droplet region). The generalised large interface model (GLIM), however, a multi-regime approach implemented in the version 7.0 of the neptune_cfd software, is able to differentiate the water film, where liquid/bubble interactions are predominant from the gas region where gas/droplet interactions are predominant, and gives nice qualitative results. Finally, this paper shows that the interfacial heat transfer model of Berne for superheated liquids could accurately predict the evolution of the water temperature over time.

Modelling of flashing phase change has been challenging due to it occurring at high pressures and temperatures. Unlike the more established flash boiling models, flash evaporation modelling is a work in progress and a reliable model applicable at different flow rates is much needed. In this work, a limited evaporation model is developed and tested for experimental cases from the Brookhaven National Laboratories (BNL), using an open source software OpenFOAM. A dual diameter approach is used with different models to calculate the heat transfer coefficient and interphase momentum forces. The mass transfer rates are limited and the limit is based on the critical work of nucleation. It is found that this new model is able to adjust its mass transfer rates based on different flow rates and to provide very good compliance for area averaged pressure and volume fractions. The importance of inter-momentum forces used in the Euler- Euler scheme in predicting the momentum transfer in bubble dominant flows is discussed. The predictions for radial distribution of volume fractions, however, do not match very well with experiments and possible strategies to improve them are elaborated upon. Finally, sensitivity studies are conducted on the model parameters and their effects on pressure and volume fractions are discussed. • Segregation of nucleation diameter and flow field diameter. • Use of critical work parameter for inception of mass transfer. • Model takes into account metastability during phase change. [ABSTRACT FROM AUTHOR]

The development of novel upper-stage rocket engines with storable cryogenic liquids and laser ignition requires a detailed understanding of the processes prior to ignition. Due to the low atmospheric pressure at high altitudes or in space, the liquid is injected below its saturation conditions, causing bubble nucleation, growth, and spray break-up, referred to as flash evaporation. Given the multiscale nature of the phenomenon, modeling and simulating this intricate process pose challenges. Common strategies, like the Eulerian–Lagrangian method, encounter limitations in representing spray break-up dynamics and providing initial data, such as the droplet size and number distribution. On the other hand, Euler–Euler methods cannot resolve the interface for all length scales involved, and the information about the surface interface is lost. Therefore, this work introduces an extension of the Eulerian–Lagrangian spray atomization model (ELSA) for flashing sprays, used to regain the information about mean droplet size. The model incorporates terms for flashing break-up and droplet evaporation and is validated against a cryogenic liquid nitrogen test case, reflecting conditions pertinent to cryogenic fuel injection at high altitudes. Comparative analyses with standard ELSA and a second model from the literature highlight the significance of accounting for the flashing process in spray break-up and droplet formation dynamics. This work contributes to a refined understanding of the break-up process in flashing sprays, offering potential advancements in spray modeling for aerospace applications. [Display omitted] • ELSA model for cryogenic flashing sprays. • Novel spray break-up modeling based on bubble growth rate before merging. • Prediction of Sauter mean diameter after spray break-up. [ABSTRACT FROM AUTHOR]

The differences between LH 2 , LNG and pressurized NH 3 dispersion are investigated using a new adiabatic mixing model which is based on Raoult's law and PH-flashing techniques for ideal mixtures and accounts for phase changes of the released substance and all ambient air components. Model validation is performed first against recent LH 2 experiments and older experiments involving LNG and NH 3 releases with reasonable agreement. The intercomparison analysis performed next assumes the given substance released at its boiling point temperature either as liquid or vapour. Ambient air is assumed composed of N 2 , O 2 and H 2 O with relative humidity either zero or 100%. The performed comparative assessment addresses the temperature versus molar fraction dependence, the condensed phase appearance conditions, the variation of the amount of the condensed phase in the mixture and its composition and finally important safety related parameters like the O 2 /N 2 and fuel/(fuel + O 2) ratios. It is found that for all three substances considered the temperature-molar fraction relation is significantly affected by source vapour quality and to less but still important extent by ambient air relative humidity. It is also found that for H 2 releases the stoichiometric ratio can be reached in the condensed phase (due to O 2 enrichment) and that this is not possible for CH 4 and NH 3 releases. The present model can be used as an engineering tool for adiabatic mixing calculations. • The new adiabatic mixing model accounts for phase change of all mixture components. • The model is validated against LH 2 , LNG and NH 3 dispersion experiments. • The temperature-molar fraction relation depends strongly on source vapour quality. • O 2 enrichment of the dry air in the condensed phase is quantified. • Stoichiometry in the condensed phase can be reached for H 2 but not for CH 4 and NH 3. [ABSTRACT FROM AUTHOR]

The flashing flow in a Moby_Dick converging-diverging nozzle under pressurized hot water from 460.5 to 483.5 K is simulated using a homogeneous compressible water-vapor two-phase flow model. The kinematic and thermodynamic mass transfer are accessed using the cavitation model based on the Hertz-Knudsen-Langmuir equation. Our simplified thermodynamic model is coupled with the governing equations to capture the phase-change heat transfer. This numerical method proved its reliability through a comparison with available experimental data of flow parameters inside the nozzle. Consequently, the present numerical method shows good potential for simulating the flashing flow under pressurized hot water conditions. The satisfying prediction of averaged flow parameters with a slight improvement compared to reference numerical data is reproduced. The results confirm a noticeable impact of the thermodynamic effect on the mechanism of flashing flow, resulting in a considerable decrease in the flow temperature and the saturated vapor pressure. The flashing nonequilibrium is significantly decreased, forcing the flashing flow to be classified as the usual cavitation behavior and better suited to homogeneous model. While the temperature drop is highly dependent on evaporation, the thermodynamic suppression is influenced by the condensation. The suppression effect, unobserved in water at a lower temperature in previous studies, is noticeable for the pressurized hot water flow characterized by the cavitation mechanism. The vapor void fraction decreased considerably in the radial and axial directions as the water temperature rose to 483.5 K in this study. [ABSTRACT FROM AUTHOR]

The world's first Liquefied Hydrogen (LH2) Carrier which will transport LH2 from Australia to Japan has been built. At Japanese port, reducing the tank pressure will be required for the safe tank operation. However, pressure reduction will cause flashing, leading to an excess of the venting capacity or liquid leakage. Hence, the purpose of this research is to clarify the pressure reduction rate and liquid behavior through experimental and numerical approaches respectively. Pressure reduction experiment under high liquid level condition was conducted by using 30 m3 tank filled with saturated LH2. The experiment showed that the pressure recovery occurred at the beginning of depressurization, and then the pressure decreased based on the equilibrium state. From numerical analysis by VOF based in-house CFD code, it was found that the pressure recovery was caused by the boiling delay, and the tank pressure followed the saturation pressure after the liquid fully stirred. • Pressure reduction experiment with large-scale LH2 tank was conducted under the high liquid level condition. • Pressure recovery occurred at the beginning of the experiment. • Based on thermodynamic analysis, pressure decreased following the equilibrium state after the pressure recovery. • The boiling delay caused the pressure recovery phenomenon. [ABSTRACT FROM AUTHOR]

Flashing flow is encountered in many industrial systems involving nozzles, valves and decompression of vessels and pipes. In the context of CO 2 capture and storage (CCS), the design of safe and efficient CO 2 transportation systems requires accurate flashing models, e.g., for safety analysis of pipe fractures and to predict the mass flow through relief valves. We propose a homogeneous flashing model (HFM) for flashing flow accounting for the underlying physical phenomena of the phase change: bubble nucleation, coalescence, break-up and growth. Homogeneous nucleation is modeled using classical nucleation theory and heterogeneous nucleation is approximated with constant rates of bubble creation and mass transfer from liquid to vapor. The flashing flow model is fitted for CO 2 pipe depressurization data at various initial conditions. We find that the same, constant model parameters can be applied for the whole set of depressurization cases considered, as opposed to the conventional homogeneous relaxation model which typically is tuned on a case-by-case basis. For depressurization paths where the fluid state passes close to the critical point, we demonstrate that an accurate description of the flashing process along the length of the pipe can only be achieved when both homogeneous and heterogeneous nucleation are accounted for. [Display omitted] • We present a homogeneous flashing model (HFM) for flashing flow. • The mass transfer during flashing is modeled based on nucleation theory. • The HFM is fitted and compared to experimental data from CO 2 depressurization tests. • Both homogeneous and heterogeneous nucleation are key to reproduce the test results. • The mass-transfer model is more general than models applying relaxation parameters. [ABSTRACT FROM AUTHOR]

The estuarine firefly, Pteroptyx tener, aggregates in the thousands in mangrove trees lining tidal rivers in Southeast Asia where they engage one another in a nocturnal, pre-mating ritual of synchronised courtship flashes. Unfortunately, populations of the species by virtue of being restricted to isolated estuarine rivers systems in the region, are at risk of genetic isolation. Because of this concern we undertook the task of sequencing and characterising the mitochondrial DNA genome of P. tener, as the first step towards helping us to characterise and better understand their genetic diversity. We sequenced and assembled the mitochondrial DNA genome of P. tener from two male and female specimens from the district of Kuala Selangor in Peninsular Malaysia and announce the molecules in this publication. We also reconstructed the phylogenetic trees of all available lampyrids mitogenomes and suggest the need to re-examine our current understanding of their classification which have largely been based on morphological data and the cox1 gene. Separately, our analysis of codon usage patterns among lampyrid mitogenomes showed that the codon usage in a majority of the protein-coding genes were non-neutral. Codon usage patterns between mitogenome sequences of P. tener were, however, largely neutral. Our findings demonstrate the usefulness of mitochondrial genes/mitogenomes for analysing both inter- and intra- specific variation in the Lampyridae to aid in species discovery in this highly variable genus; and elucidate the phylogenetic relationships of Pteroptyx spp. from the region. [ABSTRACT FROM AUTHOR]

The influence of the negative pressures of Cavitation and Flashing phenomena in the formation of “scallops”, within karstic caves, is hereby studied. In this sense, the particular case of the Chorros Cave (Albacete, Spain) is analyzed, and the theory of the inverse siphon is proposed in order to explain the “Reventón” phenomenon.

The static correlations from RELAP5 and TRACE as well as the interfacial area transport equation (IATE) are benchmarked for flashing flow with selected cases from a recently published experimental data set. The RELAP5 correlation is able to predict the interfacial area concentration more accurately than the TRACE correlation. The one-group decoupled IATE, supplied with experimental void fraction, shows overprediction of interfacial area concentration, especially at low-pressure conditions. Additionally, the one-group IATE is solved simultaneously with the void transport equation where at low pressures, the accuracy of the predicted interfacial area concentration improves even with the void fraction being underpredicted. However, as the pressure increases, the improving accuracy of the predicted void fraction leads to an overprediction of the interfacial area concentration. The two-group IATE is also benchmarked, first using the interfacial mass generation model from RELAP5 and TRACE and then with a model derived through a mass-energy balance approach. The accuracy of the two-group IATE is observed to be sensitive to the choice of the heat transfer length scale and Nusselt number correlations. [ABSTRACT FROM AUTHOR]

• New design of cooling cogeneration is proposed. • The concept of flashing is introduced to boost the refrigerant. • 28% of higher cooling output is resulted. • 30% of EUF is increased for the proposed system. The interest towards the integration of power and cooling is increased to improve the performance of the integrated systems. Most of the cooling cogeneration cycles are integration of Rankine cycle and vapor absorption refrigeration cycles. In this paper a new design of a cooling cogeneration cycle is proposed operated by aqua-ammonia as working fluid. In addition to the basic cogeneration cycle, a flashing chamber is incorporated, which will boost the refrigerant flow rate without any additional heat supply. The system is analyzed at variable parameters of hot fluid supply temperature, strong solution concentration, ammonia vapor concentration and circulating water temperature to study the effect of turbine power output, cooling output, COP, cycle thermal efficiency, plant and cycle energy utilization factor (EUF) and solar collector area. The performance of the proposed cogeneration system at 150 °C of hot fluid supply temperature and 30 °C of circulating water temperature with 0.5 of strong solution concentration are as follows power of 13.82 kW, cooling of 429.95 kW, COP of 0.56, cycle thermal efficiency of 1.78%, collector area of 4.44 m2/kW, and cycle and plant EUF are 0.56 and 0.23, respectively. [ABSTRACT FROM AUTHOR]

The greater blue-ringed octopus (Hapalochlaena lunulata) is one of three venomous octopuses well-known for the iridescent blue rings on the skin and dangerous toxin. However, the understanding of this octopus at the juvenile phase is limited compared to the adult phase. The other two venomous octopuses (Hapalochlaena fasciata and Hapalochlaena maculosa) have also not been thoroughly examined at the juvenile stage. We collected a juvenile greater blue-ringed octopus from the coastal waters of the Ryukyu Archipelago, Japan, and maintained it in captivity for observation. Five days after beginning rearing, iridescent blue rings, similar to those in the adult, appeared on the entire skin of the octopus and continued to be expressed with varying intensity. When the octopus was behaving aggressively it flashed the blue rings. Episodic antagonistic behaviour against the experimenters was also observed. [ABSTRACT FROM AUTHOR]

• The operation characteristics of the flashing-driven NC-IPWR are analyzed. • The self-regulation mechanisms contribute to the reactor's transient performance. • The effects of design parameters on reactor's transient characteristics are revealed. • Improvements on the operation scheme are proposed to deal with the instability at low load conditions. The numerous self-regulation mechanisms existing in the flashing-driven natural circulation integrated PWR (NC-IPWR) make its operation characteristics significantly different from typical PWRs or BWRs. This work presents an adequate operation scheme and a corresponding control strategy according to the reactor's operation characteristics. The thermal-hydraulic characteristics of the flashing-driven NC-IPWR are analyzed under the proposed operation scheme by using RELAP5 code. The effects of different design parameters related to the reactor's transient performance are revealed. In light of the instability phenomenon occurred at the low load conditions, the OTSG grouping operation scheme and the pressure sliding operation scheme are proposed to extend the reactor's stable operation region. [ABSTRACT FROM AUTHOR]

• Flashing front propagation (FFP) is studied in vertical tubes with small diameters. • The effect of the tube diameter on the sustainability of the FFP is observed. • The sustainability of the FFP is determined in terms of the minimum Ja and the Bo. • An empirically introduced model allows predicting the superficial velocity of FFP. Flashing is a classical phenomenon in the discharging process of liquid to the high vacuum environment in space, as well as in nuclear power engineering, chemical engineering, and other engineering fields. To predict the discharge process and ensure the safety of space activities, a better understanding of its laws is needed. In this paper, flashing front propagation in vertical small tubes is experimentally studied under the condition of rapid depressurization. Experiments are carried out with degassed distilled water under different tube diameters and initial temperatures (superheats). The sustainability of flashing front propagation is confirmed to be influenced by superheat, tube diameter and gravity. A correlation is proposed with the Jacob number and Bond number to summarize the sustainability condition. The superficial velocity of flashing front propagation shows to be related to multiple factors such as superheat, tube diameter and downstream pressure. An empirical correlation is proposed to predict the superficial velocity and it agrees well with existing data. [ABSTRACT FROM AUTHOR]

The ‘disco’ clam Ctenoides ales (Finlay, 1927) is a marine bivalve that has a unique, vivid flashing display that is a result of light scattering by silica nanospheres and rapid mantle movement. The eyes of C. ales were examined to determine their visual capabilities and whether the clams can see the flashing of conspecifics. Similar to the congener C. scaber, C. ales exhibits an off-response (shadow reflex) and an on-response (light reflex). In field observations, a shadow caused a significant increase in flash rate from a mean of 3.9 Hz to 4.7 Hz (P=0.0016). In laboratory trials, a looming stimulus, which increased light intensity, caused a significant increase in flash rate from a median of 1.8 Hz to 2.2 Hz (P=0.0001). Morphological analysis of the eyes of C. ales revealed coarsely-packed photoreceptors lacking sophisticated structure, resulting in visual resolution that is likely too low to detect the flashing of conspecifics. As the eyes of C. ales are incapable of perceiving conspecific flashing, it is likely that their vision is instead used to detect predators.