Jet Propagation Research Articles

Approaching ballistic motion in 3D simulations of gamma-ray burst jets in realistic binary neutron star merger environments

The concomitant observation of gravitational wave and electromagnetic signals from a binary neutron star (BNS) merger in 2017 confirmed that these events can produce relativistic jets responsible for short gamma-ray bursts (sGRBs). The complex interaction between the jet and the surrounding post-merger environment shapes the angular structure of the outflow, which is then imprinted in the prompt and afterglow sGRB emission. The outcome of relativistic (magneto)hydrodynamic simulations of jets piercing through post-merger environments is often used as input to compute afterglow signals that can be compared with observations. However, for reliable comparisons, the jet propagation should be followed until nearly ballistic regimes, in which the jet acceleration is essentially over and the angular structure is no longer evolving. This condition is typically reached in 2D simulations, but not in 3D ones. Our goal is to extend a (specific) jet simulation in 3D up to a nearly ballistic phase and analyse the overall dynamical evolution from the jet breakout. Our work is based on a previous 3D magnetohydrodynamic jet simulation employing a realistic environment imported from a BNS merger simulation, extended here far beyond the evolution time originally covered. After approximately 3 seconds of the jet evolution on the original spherical grid, we remapped the system into a uniform Cartesian grid and reached about 10 seconds without loss of resolution. The specific jet considered here struggled to pierce the dense surroundings, resulting in a rather asymmetrical emerging outflow with a relatively low Lorentz factor. Analysis of the energy conversion processes and corresponding acceleration showed that at the end of our simulation, 98% of the energy is in kinetic form. Moreover, at that time the angular structure is frozen. We thus obtained suitable inputs for computing the afterglow emission. Our procedure is general and applicable to any jet simulation of the same kind.

The effects of jet Lorentz factor on a relativistic astrophysical jet

In this Letter, the numerical simulation of axisymmetric hydrodynamic relativistic jet propagation was performed by solving the hydrodynamic relativistic Euler equation using the computer code PLUTO [Mignone et al., Astrophys. J. Suppl. Ser. 170, 228 (2007)]. The detailed flow features involved in this relativistic jet propagation has been thoroughly discussed in this present numerical study. The effect of the jet Lorentz factor (Γj) on the shock–turbulence interaction has been studied by analyzing the divergence of the Lamb vector (L=ω×U). The strong coexistence of two layers ∇·L<0 and ∇·L>0 enhances the momentum transfer due to energy difference, causing turbulence amplification.

Numerical simulation of YSO jet collimated by toroidal magnetic fields and radiative cooling effect

Abstract The mechanism of generation and collimation of young stellar object jets remains an unsolved problem and is a research hotspot in contemporary astrophysics. Here, we conducted a two-dimensional cylindrical coordinates simulation experiment using radiative magnetic-hydro-dynamic FLASH code and systematically analyzed the effects of toroidal magnetic fields generated by Biermann battery term and radiative cooling effect on jet evolution. In the simulation, strong toroidal magnetic fields are generated at the boundary of the plasma flow. A comparison of jets generated in different cases indicates that the magnetic fields play a significant role in hydrocarbon (CH) plasma jet collimation, surpassing the impact of radiative cooling effects. Additionally, it is observed that the magnetic fields can alter knots velocities. This platform provides a way to investigate the role of toroidal magnetic fields in jet evolution without external devices and provides a better understanding of the evolution of protostellar jets.

Propagation of untwisting solar jets from the low-beta corona into the super-Alfvénic wind: Testing a solar origin scenario for switchbacks

Context. Parker Solar Probe’s (PSP) discovery of the prevalence of switchbacks (SBs), localised magnetic deflections in the nascent solar wind, has sparked interest in uncovering their origins. A prominent theory suggests these SBs originate in the lower corona through magnetic reconnection processes, closely linked to solar jet phenomena. Jets are impulsive phenomena, observed at various scales in different solar atmosphere layers, associated with the release of magnetic twist and helicity. Aims. This study examines whether self-consistent jets can form and propagate into the super-Alfvénic wind, assesses the impact of different Parker solar wind profiles on jet dynamics, and determines if jet-induced magnetic untwisting waves display signatures typical of SBs. Methods. We employed parametric 3D numerical magnetohydrodynamics (MHD) simulations using the Adaptively Refined Magnetohydrodynamics Solver (ARMS) code to model the self-consistent generation of solar jets. Our study focuses on the propagation of solar jets in distinct atmospheric plasma β and Alfvén velocity profiles, including a Parker solar wind. We explored the influence of different atmospheric properties thanks to analysis techniques such as radius-time diagrams and synthetic in situ velocity and magnetic field measurements, akin to those observed by PSP or Solar Orbiter. Results. Our findings demonstrate that self-consistent coronal jets can form and then propagate into the super-Alfvénic wind. Notable structures such as the leading Alfvénic wave and trailing dense-jet region were consistently observed across different plasma β atmospheres. The jet propagation dynamics are significantly influenced by atmospheric variations, with changes in Alfvén velocity profiles affecting the group velocity and propagation ratio of the leading and trailing structures. U-loops, which are prevalent at jet onset, do not persist in the low-β corona but magnetic untwisting waves associated with jets exhibit SB-like signatures. However, full-reversal SBs were not observed. Conclusions. These findings may explain the absence of full reversal SBs in the sub-Alfvénic wind and illustrate the propagation of magnetic deflections through jet-like events, shedding light on possible SB formation processes.

Comparative study on the energy decay patterns and vortex characteristics of submersible thrusters under different structural configurations

Submersible thrusters (STs) are crucial for applications such as wastewater treatment, but their energy decay mechanisms and flow characteristics remain inadequately understood. This study compares the original ST, a shrouded ST (SGT), and a configuration with both guide vanes and a shroud (SGVT), focusing on energy decay, jet evolution, vortex dynamics, and entropy production. Numerical simulations are conducted using adaptive mesh refinement and delayed detached eddy simulation turbulence models to capture the complex flow structures. Findings indicate that ST undergoes rapid energy decay with pronounced jet energy fluctuations in the transition phase (z/D = 4–8), whereas SGT and SGVT models exhibit slower decay rates, delaying the half-power decay position by 71% and 157.2%, respectively. In the ST jet, vortex interactions, particularly between tip vortices (TVs) and hub vortices (HVs), lead to jet instability, turbulence, and increased entropy production. SGT mitigates centrifugal forces by suppressing tangential velocity, delaying jet instability to downstream regions (z/D = 7). SGVT, by breaking the spiral TV and trailing edge root vortices into smaller-scale vortex clusters and reducing tangential velocity at the blade root, suppresses both TV and HV-induced instability. As a result, the high-entropy production wake width in SGVT is only 50% of that in ST. Instability in the SGVT jet is primarily governed by Kelvin–Helmholtz (K-H) instabilities in the shear layer, which, though weak, support downstream jet propagation. The increased entropy production in SGVT at early stages (z/D = 2–4) is attributed to the formation of small-scale TV clusters.

OPTIMIZATION OF HYDRODYNAMIC PARAMETERS OF DRILLING FLUIDS FOR IMPROVED CUTTINGS TRANSPORT IN HORIZONTAL WELLS

In horizontal portions of small-bore well holes, improper cuttings transportation results in high torque and raises the possibility of the drill being stuck, shortening its service life and endangering safe operation. A transport approach utilizing pulsed drilling fluid based on a shunt relay mechanism is suggested since the traditional cuttings transport method is ineffective at removing the cuttings bed. The transport of cuttings in horizontal small-bore wells is modeled numerically using three layers. The cuttings transport is examined in terms of the cuttings concentration, cuttings velocity, and cuttings bed movement distance using both numerical models and tests. The best pulse parameters are identified by adjusting the pulsed drilling fluid velocity cycle, amplitude, and duty cycle at the annulus inlet and assessing the impact on cuttings transport. The findings demonstrate that pulsed drilling fluid can be used to improve wellbore cleaning, lower cuttings concentration, and increase the cuttings bed's transport distance and moving cutting velocity. A steady flow rate of drilling fluid is used in the traditional cuttings transportation method. Simulations using the three-layer numerical model show that the cuttings bed's movement distance is decreased to the point where the wellbore's cleaning effect falls short of its intended level when the cuttings bed's height in the annulus surpasses a critical value. A technique using pulsed drilling fluid has been suggested to enhance transportation. By altering the drilling fluid's flow rate, this continuously affects the cuttings. Because pulsed jet drilling technology can effectively boost drilling speed, downhole drilling instruments that use pulsed jets are outfitted with spiral pressure intensifiers and variable-frequency pulse jet generators. According to field tests, using pulsed drilling fluid improves cuttings transport efficiency and lessens the impact of chipping. The majority of cuttings transport research to date has been on how cuttings behave under typical drilling fluid flow conditions. Relatively few studies exist about the destruction of the cuttings bed or the transportation of cuttings under conditions of pulsed drilling fluid. This research establishes a three-layer numerical model under pulsed fluid circumstances based on a shunt relay mechanism. This research describes the transport of cuttings in horizontal well sections under pulsed drilling fluid circumstances in terms of factors, such as the cuttings concentration, the cuttings bed's distance traveled, and the moving cuttings velocity, using both numerical models and tests. Furthermore, the ideal pulse parameters are found, which serves as a crucial guide for designing cuttings transport using pulsed drilling fluid tools. A three-layer numerical simulation model of cuttings transport utilizing a pulsed drilling fluid in the horizontal section of a narrow-bore hole is constructed in the second section of the article, which is based on actual onsite working conditions. The experimental apparatus and procedures are presented in the third section, and the experimental data are used to study the behavior of cuttings transport by the pulse drilling fluid. The cuttings transport behavior for various values of th is examined in the fourth section using finite element software. Keywords: CFD model, cuttings bed, pulsed drilling fluid, and horizontal well drilling

Combustion characteristics of Ammonia/Air mixture ignited by flame jet with and without hydrogen injection in Pre-Chamber

Ammonia is one of the important fuels that can promote the achievement of carbon neutrality, but its combustion characteristics are not conducive to its application in engines. Injecting hydrogen in the pre-chamber to form a flame jet to ignite the ammonia/air mixture is a method to improve the combustion of ammonia. This ignition method was investigated with the constant volume combustion chamber, high-speed video camera observation and the main-chamber pressure analysis. The flame behavior and combustion characteristics were compared with those ignited by the ammonia flame jet. Hydrogen flame jet significantly enhanced the combustion of the mixture and extended the lean flammability limit. Under conditions of hydrogen injection, the pressure rise delay and combustion duration became shorter, the average heat release rate became higher, and the combustion process was more stable. The hydrogen flame jet rapidly penetrated the main-chamber and impinged on the lower surface, generating intense turbulence. As a result, the combustion pressure took less time to rise from 10% to 50% than it did to go from 50% to 90%. This was different from the situation without hydrogen injection, where time required for both was similar. The hydrogen flame jet was shuttle-shaped when touching the lower surface owing to the rapid combustion speed of hydrogen, while the ammonia flame jet was spindle-shaped with the flame kernel in the center. The combustion process of the flame jet igniting the mixture exhibited two peaks in the heat release rate, reflecting two combustion stages dominated by the flame jet and flame propagation.

Propagation of Gamma-Ray Burst Relativistic Jets in Active Galactic Nucleus Disks and Its Implication for Gamma-Ray Burst Detection

The accretion disks of supermassive black holes (SMBHs) harboring in active galactic nuclei (AGN) are considered to be an ideal site for producing different types of gamma-ray bursts (GRBs). The detectability of these GRB phenomena hidden in AGN disks is highly dependent on the dynamical evolution of the GRB relativistic jets. By investigating the reverse- and forward-shock dynamics due to the interaction between the jets and AGN disk material, we find that the relativistic jets can successfully break out from the disks only for a sufficiently high luminosity and a long enough duration. In comparison, relatively normal GRB jets are inclined to be choked in the disks unless the GRBs occur near an SMBH with relatively low mass (e.g., ∼106 M ⊙). For the choked jets, unlike normal GRB prompt and afterglow emission, we can only expect to detect emission from the forward shock when the shock is very close to the edge of the disks, i.e., at the shock breakout emission and subsequent cooling of the shock.

Energy efficiency of reactive species generation in radio frequency atmospheric pressure plasma jets driven by tailored voltage waveforms in a He/O2 mixture

Abstract The effect of the shape of the applied voltage waveform on the energy efficiency of reactive species generation is investigated in an atmospheric pressure RF microplasma jet operated in a He/O2 mixture (99.5%/0.5%) based on a one-dimensional hybrid fluid-kinetic simulation method. Using a tailored waveform synthesized from four consecutive harmonics (with a base frequency of f b = 13.56 MHz and amplitudes of ( 160 / k ) V for the k-th harmonic), it is shown that by changing the identical phases of the even harmonics in the waveform, ϕ, the generation efficiencies of three specific reactive species (helium metastables, atomic and vibrationally excited oxygen), defined as the ratio of mean density and input plasma power, attain their maxima for different values of ϕ, due to changes in the Electron Energy Probability Function (EEPF). The phase control of the EEPF and its critical role in modulating generation energy efficiencies are explained in detail. The simulation results are verified by experimental (Phase Resolved Optical Emission Spectroscopy and Two Photon Absorption Laser Induced Fluorescence) data.

Magnetic dissipation in short gamma-ray-burst jets

Aims. Short gamma-ray bursts originate when relativistic jets emerge from the remnants of binary neutron star (BNS) mergers, as observed in the first multi-messenger event GW170817–GRB 170817A, which coincided with a gravitational wave signal. Both the jet and the remnant are believed to be magnetized, and the presence of magnetic fields is known to influence the jet propagation across the surrounding post-merger environment. In the magnetic interplay between the jet and the environment itself, effects due to a finite plasma conductivity may be important, especially in the first phases of jet propagation. We aim to investigate these effects, from jet launching to its final breakout from the post-merger environment. Methods. We used the PLUTO numerical code to perform 2D axisymmetric and full 3D resistive relativistic magnetohydrodynamic (MHD) simulations, employing spherical coordinates with spatial radial stretching. We considered and compared different models for physical resistivity, which must be small but still dominating over the intrinsic numerical dissipation (which yields unwanted smearing of structures in any ideal MHD code). Stiff terms in the current density are treated with IMplicit-EXplicit Runge Kutta algorithms for time-stepping. A Synge-like gas (Taub equation of state) is also considered. All simulations were performed using an axisymmetric analytical model for both the jet propagation environment and the jet injection; we leave the case of jet propagation in a realistic environment (i.e., imported from an actual BNS merger simulation) to a future study. Results. As expected, no qualitative differences are detected due to the effect of a finite conductivity, but significant quantitative differences in the jet structure and induced turbulence are clearly seen in 2D axisymmetric simulations, and we also compare different resistivity models. We see the formation of regions with a resistive electric field parallel to the magnetic field, and nonthermal particle acceleration may be enhanced there. The level of dissipated Ohmic power is also dependent on the various recipes for resistivity. Most of the differences arise before the breakout from the inner environment, whereas once the jet enters the external weakly magnetized environment region, these differences are preserved during further propagation despite the lower grid refinement. Finally, we show and discuss the 3D evolution of the jet within the same environment in order to highlight the emergence of nonaxisymmetric features.

Sensitized Reynolds stress modeling of a bubbly jet emerging into a water cross-flow

The present work is concerned with the computational study of an air–water mixture stream emanating from a nozzle submerged in a water cross-flow inside a rectangular open channel to form a curved, intensively dispersed, bubbly jet. The work focuses on evaluating the predictive performance of an eddy-resolving turbulence model applied to the described case of a multiphase gas–liquid flow system characterized by a variety of closely coupled phenomena, including: turbulence anisotropy-induced secondary motion, free surface flow, bubbly jet propagation, and the varying interaction dynamics of the carrier water flow with the air bubble dispersion. Correspondingly, an appropriately extended differential near-wall Reynolds stress model, which describes the dynamics of unresolved subscale structures within the Sensitized Reynolds-Averaged Navier–Stokes (RANS) computational framework, is currently used in conjunction with a two-way coupled Euler–Lagrange approach to simulate this gas-water bubbly flow, with the operating and boundary conditions following the experimental reference of Zhang and Zhu (2013). Accordingly, the conditions at the free surface are adequately derived for all components of the residual turbulence stress tensor and the corresponding length scale determining variable. It is shown that the statistics of the bubble phase can be accurately captured, and the proper-orthogonal-decomposition analysis of the dynamic properties of the flow reveals at least two large-scale transient effects associated with the bubbly jet. Furthermore, in the preliminary part of this work it is shown that the currently applied turbulence model can be successfully used to correctly capture the effects of Reynolds stress anisotropy in the single-phase open-channel configuration, representing the incoming flow field of the main two-phase flow configuration.

Совершенствование конструкций установок струйных насосов для добычи нефти

The characteristics of jet pump installations are given, which are used mainly for low-yield wells in oil production whose flow rate is less than 10 m3/day. It is noted that jet pump installations have a relatively low efficiency of not exceeding 0.35, and it is almost equal to the efficiency of electric drive pump installations and downhole rod pump installations when extracting oil from wells with low flow rates of up to 20 m3/day. The advantages of jet pump installations over other types of downhole pumping installations in difficult oil production conditions are shown. With flow rates up to 150 m3/day. Costs for oil production using jet pump installations are minimal compared to other installations. A brief analysis of the designs of jet pumps, their main overall dimensions and weight is provided. A brief overview of scientific, technical and patent literature on jet pump installations is given. By changing the design of nozzles, confusers, diffusers, working chambers of jet pumps, as well as improving the jet pump installations as a whole when used in tandem with other types of well installations, their productivity, operating efficiency and reliability can be increased. It is noted that the parameters of jet pumps can be obtained by calculation based on the theory of mixing two flows, the theory of jet propagation in a mass of stationary or moving liquid and the mechanics of bodies of variable mass. The main design parameters of jet pump units are feed, pressure, ejection coefficient, power and efficiency. These parameters can also be determined experimentally. A laboratory jet pump unit has been developed. Experiments have shown that with an increase in the flow rate of the working fluid, the flow rate of the mixture and the working pressure, the ejection coefficient and efficiency decrease. In the future, experiments will be continued with various designs of jet pump elements.

Characteristics of Shaped Charge Jets by the Shape of the Inhibitor Inserted into the Liner

The performance of a shaped charge bomb depends on the explosive performance, liner precision machining and manufacturing quality. The key performance is how uniformly the liner transforms into a jet. In order to reduce the performance of the shaped charge bomb from a protection point of view, this study investigated the characteristics of the jet formation and progression by inserting inhibitors of different shapes into the liner using flash X-ray experimental analysis techniques. The larger the volume filled inside the liner, the lower the rate of high-speed jet generation, which was well confirmed by experiments. Due to the effect of the inhibitor, it takes a considerable amount of time delay to form a jet after explosion compared to a normal shot, and quantity and mass of jet particles that can contribute to penetration are decreased, and the penetration power is also greatly reduced due to the scattering of segmented jets.

Propeller scour phenomenon in the presence of a quay-wall and currents

Investigating the interaction between flow intensity and a ship propeller jet scouring process is paramount to predict scour dimensions in mooring sites in navigation channels, for instance. While the condition of still water is typical in protected mooring sites, in other real-world conditions, like docking in waterways, the presence of an additional flow approaching a rotating propeller can induce changes in the propeller jet hydrodynamics and in turn in the scouring process. Note that, although ship-hull and rudders influence the jet propagation and the flow field, the present research project aimed at studying the propeller-inducing effects only. Literature studies that have relied on this assumption are rarely found, with only a few examining the impact of the intensity of the flow on the propeller jet scour. This study presents an experimental campaign aimed at assessing the effects of flow intensity on propeller jets in confined conditions. Specifically, three different flow intensities and three propeller distances from a vertical quay-wall were tested. The findings are presented through profiles of the scoured bed, and bathymetries at the equilibrium condition and empirical formulas for calculating the principal dimensions of the scour holes are given.To explore the intricate hydrodynamics and understand how the intensity of the flow affects the scour hole development, and to investigate boundary effects on the flow field, we performed Reynolds-Averaged Navier–Stokes (RANS) simulations. These simulations were applied to the three-dimensional scoured bathymetry in a state of equilibrium. The satisfactory match between numerical results and sampled velocities at the equilibrium stage ensures the reliability of the simulations. To the authors’ knowledge, these configurations had not been previously simulated, owing to the complexities involved in computing a moving mesh in presence of a bathymetry and a confining vertical wall. The results offer the first numerical demonstration of boundary effects on the characteristics of propeller jets both in the presence and in the absence of an additional channel flow.

Toward the Direct Simulation of the Quasi‐Biennial Oscillation in a Global Storm‐Resolving Model

AbstractThis study presents the first attempt to simulate a full cycle of the quasi‐biennial oscillation (QBO) in a global storm‐resolving model (GSRM) that explicitly simulates deep convection and gravity waves instead of parameterizing them. Using the Icosahedral Nonhydrostatic (ICON) model with horizontal and vertical resolutions of about and , respectively, we show that an untuned state‐of‐the‐art GSRM is already on the verge of simulating a QBO‐like oscillation of the zonal wind in the tropical stratosphere for the right reasons. ICON shows overall good fidelity in simulating the QBO momentum budget and the downward propagation of the QBO jets in the upper QBO domain (25–35 km). In the lowermost stratosphere, however, ICON does not simulate the downward propagation of the QBO jets to the tropopause. This is the result of a pronounced lack of QBO wave forcing, mainly on planetary scales. The lack of planetary‐scale wave forcing in the lowermost stratosphere is caused by an underestimation of planetary‐scale wave momentum fluxes entering the stratosphere. We attribute this lack of planetary‐scale wave momentum fluxes to a substantial lack of convectively coupled equatorial waves (CCEWs) in the tropical troposphere. Therefore, we conclude that in ICON, simulating a realistic spatio‐temporal variability of tropical deep convection, in particular CCEWs, is currently the main roadblock toward simulating a reasonable QBO. To overcome this intermediate situation, we propose to aim at an improved explicit simulation of tropical deep convection by retuning the remaining parameterizations of cloud microphysics and vertical diffusion, and by increasing the horizontal resolution.

Disk mass after a binary neutron star merger as a constraining parameter for short gamma-ray bursts

Context. The coincident detection of GW170817 and gamma-ray burst GRB170817A marked a milestone for the connection between binary neutron star (BNS) mergers and short gamma-ray bursts (sGRBs). These mergers can lead to the formation of a black hole that is surrounded by a disk and to the generation of a powerful jet. It spends energy to break free from the merger ejecta, and then a portion of it is dissipated to produce observable emissions. Aims. Our primary goal is to enhance our comprehension of BNS mergers by constraining the disk mass for a selection of sGRBs. To do this, we used the isotropic gamma-ray luminosity and corresponding emission times as key indicators. Methods. We leveraged data from GW170817 to estimate the disk mass surrounding the BNS merger remnant, and we subsequently inferred the efficiency of the accretion onto the jet. We then statistically examined other sGRB observations to estimate whether they might have been induced by BNS mergers Results. Our findings suggest that when similar physical parameters are employed as in the only observed BNS-powered GRB event, GRB170817A, a substantial fraction of sGRBs would need an unrealistically massive disk remnant. Conclusions. This observation raises the possibility that either a different mechanism powered those events or that the post-collapse disk efficiency varies significantly in different BNS merger scenarios.

The effect of non-perpendicular incidence angles on discharge characteristics in an argon atmospheric plasma jet impinging on metal, water and glass substrates

The spatial–temporal discharge behavior of an AC argon plasma jet tilted at non-perpendicular incidence angles (60°, 45°, and 30°) interacting with an ungrounded metal, water, and glass plate placed on the jet propagation track was studied by the fast-imaging technique. The conductivity of surface and incidence angles plays an essential role in the discharge current and dynamic process of the plasma jet. The nearly consistent time delay between subsequent breakdowns occurred four times for metal and two times for glass treatments. The mean luminous intensity of the plasma in one discharge cycle at the discharge area between ground electrode and target surface region for the water and glass case decreased by 39.5% and 20.5% when the incidence angle decreased from 60° to 30°, respectively. In particular, the incidence angle and gas flow rate notably impacted the spatial extension behavior created on the glass surface but had no significant difference in discharge characteristic of plasma jet with metal case. In addition, two equivalent circuit models were developed based on the simulation of the micro-discharges and the geometry of the “plasma jet–substrate” system, respectively. These results will obtain further insight into the underlying mechanisms of plasma-target interaction and facilitate the designing of appropriate jet for environmental and biomedical applications.

Towards multi-messenger observations of core-collapse supernovae harbouring choked jets

Context. Over the past decade, choked jets have attracted particular attention as potential sources of high-energy cosmic neutrinos. It is challenging to test this hypothesis because of the missing gamma-ray counterpart. An identification of other electromagnetic signatures is therefore crucial. Extended H envelopes surrounding collapsing massive stars might choke launched jets. In addition, the same progenitors are expected to produce a shock-breakout signal in the ultraviolet (UV) and optical that lasts several days. Early UV radiation in particular carries important information about the presence and nature of choked jets. Aims. While UV observations of core-collapse supernovae have so far been limited, the full potential of observations in this spectral band will soon be transformed by the ULTRASAT satellite mission with its unprecedented field of view. We investigated the detection prospects of choked jet progenitors by ULTRASAT in relation to their visibility in the optical band by the currently operating telescope ZTF. In addition, as choked jets can produce neutrinos via hadronic and photohadronic interactions in choked jets, we also investigated how neutrino observations by existing Cherenkov high-energy neutrino telescopes (e.g. IceCube and KM3NeT) can be used in association with electromagnetic signals from shock-breakout events. Methods. By considering fiducial parameters of the source population and instrument performances, we estimated the maximum redshift up to which ULTRASAT and ZTF are able to detect ultraviolet and optical signals from these explosions, respectively. Furthermore, we discuss coordinated multi-messenger observations using ULTRASAT, ZTF, and high-energy neutrino telescopes. Results. We find that ULTRASAT will double the volume of the sky that is currently visible by ZTF for the same emitting sources. This will enlarge the sample of observed Type II supernovae by ∼60%. For optimised multi-messenger detections, the delay between neutrinos produced at the shock breakout (during the jet propagation inside the stellar envelope) and ULTRASAT observations should be of ∼4 (5) days, with subsequent follow-up by instruments such as ZTF about one week later. We estimate that fewer than 1% of the core-collapse supernovae from red supergiant stars that are detectable in UV with ULTRASAT might host a choked jet and release TeV neutrinos. Electromagnetic and neutrino detections, if accompanied by additional photometric and spectroscopic follow-up with compelling evidence for a relativistic jet launched by the central engine of the source, would suggest that core-collapse supernovae harbouring choked jets are the main contributors to the diffuse astrophysical high-energy neutrino flux.

Control of photothermal liquid jets through microbubble Regulation: Fundamental mechanisms and Developing Strategies

Plasmon-induced photoacoustic streaming, considered as a potential application for micro-pumps in microfluidics, currently encounters ongoing debates concerning its fundamental mechanisms. In this study, we investigate the crucial role played by microbubbles in generation of jets in an ethanol aqueous solution. The power density threshold for bubble generation and its dependency on jet initiation are confirmed and the microbubble behavior is well regulated by manipulating the laser and liquid properties. Through simulations coupling fluidic and thermal fields, the significant role of Marangoni effect is validated in jet formation. Specifically, the temperature gradient of microbubbles is determined to be a pivotal factor in the generation of collimated jets. Additionally, factors influencing jetting, such as microbubble size and temperature gradients are studied, and noticeably, a stabilized jet lasting over 4 h is achieved based upon.

The Generation and Dynamics of a Granular Jet Induced by a Sudden Acceleration

The Generation and Dynamics of a Granular Jet Induced by a Sudden Acceleration