Jet Geometry Research Articles

Jet collimation and acceleration in the flat spectrum radio quasar 1928+738

Using time-resolved multifrequency Very Long Baseline Array data and new KaVA (KVN and VERA Array) observations, we study the structure and kinematics of the jet of the flat spectrum radio quasar (FSRQ) 1928+738. We find two distinct jet geometries as a function of distance from the central black hole, with the inner jet having a parabolic shape, indicating collimation, and the outer jet having a conical shape, indicating free expansion of the jet plasma. Jet component speeds display a gradual outward acceleration up to a bulk Lorentz factor Γmax ≈ 10 followed by a deceleration further downstream. The location of the acceleration zone matches the region where the jet collimation occurs. Therefore, this is the first direct observation of an acceleration and collimation zone (ACZ) in an FSRQ. The ACZ terminates approximately at a distance of 5.6 × 106 gravitational radii, which is in good agreement with the sphere of gravitational influence of the supermassive black hole, implying that the physical extent of the ACZ is controlled by the black hole gravity. Our results suggest that confinement by an external medium is responsible for the jet collimation and that the jet is accelerated by converting Poynting flux energy to kinetic energy.

Experimental hot-wire characterisation of the turbulent jet produced by a sweeping jet actuator in a quiescent environment

The present work presents the design and the characterisation of a sweeping jet, a fluidic actuator that has been shown to be able to enhance the aerodynamic performance of flow applications as transportation vehicles. The principles and operation of this type of actuator are detailed here. An experimental apparatus with hot-wire anemometry was installed to describe the flow topology produced by the sweeping jet. Basic analysis shows that the jet generates a flow with an average velocity of 60<Umean<100ms−1, a flow rate between 1.3 and 3 gs−1, and an oscillating frequency up to 2200Hz. The produced jet geometry is also analysed and shows interesting behaviour. The evolution of geometrical parameters is influenced by a transonic transition inside the actuator. To analyse the turbulent properties of the external flow, spectral triple decomposition is developed and used on the experimental data. A strong impact of the transition from a subsonic to a transonic regime on the produced flow is highlighted. The analysis of the turbulence produced by the sweeping jet shows a separation of the flow in three different zones detailed in the article. The study highlights promising results for future flow control implementations.

Graded jet geometry

Jet manifolds and vector bundles allow one to employ tools of differential geometry to study differential equations, for example those arising as equations of motions in physics. They are necessary for a geometrical formulation of Lagrangian mechanics and the calculus of variations. It is thus only natural to require their generalization in geometry of Z-graded manifolds and vector bundles.Our aim is to construct the k-th order jet bundle JEk of an arbitrary Z-graded vector bundle E over an arbitrary Z-graded manifold M. We do so by directly constructing its sheaf of sections, which allows one to quickly prove all its usual properties. It turns out that it is convenient to start with the construction of the graded vector bundle of k-th order (linear) differential operators DEk on E. In the process, we discuss (principal) symbol maps and a subclass of differential operators whose symbols correspond to completely symmetric k-vector fields, thus finding a graded version of Atiyah Lie algebroid. Necessary rudiments of geometry of Z-graded vector bundles over Z-graded manifolds are recalled.

EXPERIMENTAL STUDY OF DELAYING THE STALL OF THE NACA 0020 AIRFOIL USING A SYNTHETIC JET ACTUATOR ARRAY WITH DIFFERENT ORIFICE GEOMETRIES

An experimental study on the effect of active flow control using a synthetic jet mechanism on stall delay for the NACA 0020 airfoil is conducted. The experiments are carried out at an open-suction type wind tunnel at Reynolds number 5x104. In the presented experimental study, aerodynamic force measurements of the airfoil with having different orifice geometries (cylindrical, rectangular, sinusoidal, v-type, inclined rectangular) are examined by using a speaker type actuator in synthetic jet mechanism. It is observed that all different orifice geometries are effective in delaying the stall angle of NACA 0020 airfoil. However, it is observed that the inclined rectangular type of synthetic jet geometry is the most advantageous in delaying the stall of the airfoil. The effects of geometric parameters of the actuator on lift and drag coefficient of the NACA0020 airfoil are investigated. Experimental results show that among the all-orifice geometries the rectangular orifice geometry is the most effective in increasing lift coefficient of the airfoil. It is observed that there is a maximum decrease in drag at 10⁰ where the stall occurs. In addition, the decrease in drag is observed after 10 in rectangular, v-type and inclined rectangular orifice geometries.

Core shift in parabolic accelerating jets

ABSTRACT The core-shift method is a powerful method to estimate the physical parameters in relativistic jets from active galactic nuclei. The classical approach assumes a conical geometry of jets and a constant plasma speed. However, recent observations have shown that neither may hold close to the central engine, where the plasma in the jet is effectively accelerating and the jet geometry is quasi-parabolic. We modify the classical core-shift method to account for these jet properties. We show that the core-shift index may assume values in the range 0.8−1.2 or 0.53−0.8 depending on the jet geometry and viewing angle, and indices close to both values are indeed observed. We obtain expressions to estimate the jet magnetic field and the total magnetic flux in a jet. We show that the obtained magnetic field value can be easily recalculated down to the gravitational radius scale. For M87 and NGC 315, these values are in good agreement with those obtained by different methods.

Measurement of Turbulent Kinetic Energy in Hypertrophic Cardiomyopathy Using Triple-velocity Encoding 4D Flow MR Imaging.

The turbulent kinetic energy (TKE) estimation based on 4D flow MRI has been currently developed and can be used to estimate the pressure gradient. The objective of this study was to validate the clinical value of 4D flow-based TKE measurement in patients with hypertrophic cardiomyopathy (HCM). From April 2018 to March 2019, we recruited 28 patients with HCM. Based on echocardiography, they were divided into obstructed HCM (HOCM) and non-obstructed HCM (HNCM). Triple-velocity encoding 4D flow MRI was performed. The volume-of-interest from the left ventricle to the aortic arch was drawn semi-automatically. We defined peak turbulent kinetic energy (TKEpeak) as the highest TKE phase in all cardiac phases. TKEpeak was significantly higher in HOCM than in HNCM (14.83 ± 3.91 vs. 7.11 ± 3.60 mJ, P < 0.001). TKEpeak was significantly higher in patients with systolic anterior movement (SAM) than in those without SAM (15.60 ± 3.96 vs. 7.44 ± 3.29 mJ, P < 0.001). Left ventricular (LV) mass increased proportionally with TKEpeak (P = 0.012, r = 0.466). When only the asymptomatic patients were extracted, a stronger correlation was observed (P = 0.001, r = 0.842). TKE measurement based on 4D flow MRI can detect the flow alteration induced by systolic flow jet and LV outflow tract geometry, such as SAM in patients with HOCM. The elevated TKE is correlated with increasing LV mass. This indicates that increasing cardiac load, by pressure loss due to turbulence, induces progression of LV hypertrophy, which leads to a worse prognosis.

On the Theory of Ring Afterglows

Synchrotron and inverse Compton emission successfully explain the observed spectra of gamma-ray burst (GRB) afterglows. It is thought that most GRBs are products of extremely relativistic outflows and the afterglow marks the interaction of that ejecta with the surrounding matter. A faster decay of afterglow light curves at late times is indicative of nonspherical geometries, and is usually interpreted as evidence for jet geometry. Recent numerical simulations have shown that ring-like geometries are also permissible for relativistic outflows. We therefore extend the standard theory of afterglow evolution to ring geometries. An analytic prescription for the light curves and spectra produced by relativistic toroidal blast waves is presented. We compare these to their spherical and jet-like counterparts, and show that ring afterglows decay faster than spherical outflows but not as fast as jets.

Unpacking Merger Jets: A Bayesian Analysis of GW170817, GW190425 and Electromagnetic Observations of Short Gamma-Ray Bursts

We present a novel fully Bayesian analysis to constrain short gamma-ray burst (sGRB) jet structures associated with cocoon, wide-angle, and simple top-hat jet models, as well as the binary neutron star (BNS) merger rate. These constraints are made given the distance and inclination information from GW170817, observed flux of GRB 170817A, observed rate of sGRBs detected by Swift, and the neutron star merger rate inferred from LIGO’s first and second observing runs. A separate analysis is conducted where a fitted sGRB luminosity function is included to provide further constraints. The jet structure models are further constrained using the observation of GW190425, and we find that the assumption that it produced a GRB 170817–like sGRB which went undetected due to the jet geometry is consistent with previous observations. We find and quantify evidence for low-luminosity and wide-angle jet structuring in the sGRB population, independently from afterglow observations, with log Bayes factors of 0.45–0.55 for such models when compared to a classical top-hat jet. Slight evidence is found for a Gaussian jet structure model over all others when the fitted luminosity function is provided, producing log Bayes factors of 0.25–0.9 ± 0.05 when compared to the other models. However, without considering GW190425 or the fitted luminosity function, the evidence favors a cocoon-like model with log Bayes factors of 0.14 ± 0.05 over the Gaussian jet structure. We provide new constraints to the BNS merger rates of 1–1300 Gpc−3 yr−1 or 2–680 Gpc−3 yr−1 when a fitted luminosity function is assumed.

Analytical Investigation of the Impact of Jet Geometry on Aeration Effectiveness Using Soft Computing Techniques.

Jet aeration is a commonly used technique for introducing air into water during wastewater treatment. In this investigation, the efficacy of different soft computing models, namely, Random Forest, Reduced Error Pruning Tree, Artificial Neural Network (ANN), Gaussian Process, and Support Vector Machine, was examined in predicting the aeration efficiency (E20) of circular and square jet configurations in an open channel flow. A total of 126 experimental data points were utilized to develop and validate these models. To assess the models' performance, three goodness-of-fit parameters were employed: correlation coefficient (CC), root-mean-square error (RMSE), and mean absolute error (MAE). The analysis revealed that all of the developed models exhibited predictive capabilities, with CC values surpassing 0.8. Nonetheless, when it comes to predicting E20, the ANN model outperformed other soft computing models, achieving a CC of 0.9748, MAE of 0.0164, and RMSE of 0.0211. A sensitivity analysis emphasized that the angle of inclination exerted the most significant influence on the aeration in an open channel. Furthermore, the results demonstrated that square jets delivered superior aeration compared to that of circular jets under identical operating conditions.

Combined optical connectivity and optical flow velocimetry measurement of interfacial velocity of a liquid jet in gas crossflow

Liquid jet in crossflow (LJIC) is a process in which a high-speed gas crossflow deforms and shears a continuous liquid flow into tiny droplets. This study quantifies the liquid surface motion of LJIC during the primary breakup process, which has not been quantified due to the optical limitation close to the nozzle exit. The interfacial velocity of a breaking liquid jet indicates the local interaction of the gas and liquid flows and determines the initial velocity of the stripped droplets. The local interfacial liquid velocities of LJIC have only been estimated from theoretical and computational studies, which have not been evaluated from measurements. Optical Connectivity (OC) introduces a laser beam through an atomiser nozzle and relies on total internal reflection at the liquid interface to propagate the laser light inside the continuous liquid to record the instantaneous features of the interface of the continuous liquid during the primary atomisation at the near nozzle region through imaging of the emitted fluorescent intensity from the liquid flow. The current study combines Optical Connectivity with Optical Flow Velocimetry (OFV) to quantify the time-dependent, local interfacial velocity of the liquid interface structures of the LJIC for gas Weber numbers between 14.9 - 112.6 and liquid-to-gas momentum ratios between 2.1 - 36.4. The combined OC-OFV measurements of the spatial distribution of the mean and fluctuating values of the different components of the liquid interfacial velocity of LJIC demonstrate how the gaseous shear and liquid jet geometry interact to influence the atomisation process.

A comparative study of circular and rectangular bended plunging jets

In the present work we study the topology, mixing properties, turbulence quantities, dependence on the outlet geometry of a sharp-edged orifice plunging jet which first issues horizontally in air and then plunges in a water pool. The investigated orifices shapes are circular and rectangular. Data are acquired at different Reynolds numbers in the range 11000–25000, based on the orifice diameter (equal to 2 cm) and on the average exit velocity, as derived from flow rate measurements. Velocity fields in vertical and horizontal planes are measured using planar time-resolved Particle Image Velocimetry. Results show a clear asymmetry of the cross-velocity profiles both in circular and rectangular cases, with the latter that revealed a shape which is Reynolds number dependent. Axial velocity decays, potential core lengths and spreading rates highlight an opposite trend between the two jet geometries, thus suggesting a higher mixing for the lowest Reynolds number circular jet and the highest rectangular one. Plunging angle shows a dependency on Reynolds number. Moreover, it seems to play a role in the evolution of the upper and lower side of the jet due to the onset of a co-flow. Ambient mass entrainment points out the different interactions of the two plunging jets with the ambient flow: in circular case, it entrains fluid from the surroundings, from horizontal to vertical planes in streamwise direction, while in rectangular one it ejects flow from vertical to horizontal planes. Finally, Strouhal numbers are derived for main vortices frequencies along jet centerline, other than upper and lower sides.

Modelling and simulating of premixed layer in stratified fuel coolant configuration

A hypothetical severe accident in a nuclear power plant can lead to significant core damage, including melting of the core. The interaction between the molten core and the coolant water is known as a fuel–coolant interaction. One of the consequences can be a rapid transfer of a significant part of the molten corium thermal energy to the coolant in a time scale smaller than the characteristic time of the pressure relief of the created and expanding vapour. Such a phenomenon is known as a vapour explosion. Given possibly a large amount of thermal energy, initially stored in the liquid corium melt at about 3000 K, and pressure peaks of the order of 100 MPa, vapour explosion can be a credible threat to the structures, systems and components inside the reactor containment. It can also threaten the integrity of the reactor containment itself, which would lead to the release of radioactive material into the environment and threaten the general public safety. In analyses of severe accidents in nuclear power plants, a fuel–coolant interaction was mostly addressed in a geometry of a melt jet poured into a coolant pool. Based on some experimental and analytical work from the past a geometry with a continuous layer of melt under a layer of water, called stratified configuration, was believed to be incapable of producing energetic fuel–coolant interaction of sufficient magnitude to likely fail the containment. However, the results from recent experiments performed at the PULiMS and SES facilities (KTH, Sweden) with corium simulants materials contradict this hypothesis. In some of the tests, a premixing layer of ejected melt drops in water was clearly visible and was followed by strong spontaneous vapour explosions.The purpose of our research is to improve the knowledge, understanding and modelling of the fuel–coolant interaction and vapour explosion in stratified configuration. Based on the past experimental and analytical research, mechanisms for the premixed layer formation are identified and a model for the melt-coolant premixed layer formation in stratified configuration is presented. The analyses on the PULiMS and SES experimental results demonstrate the model’s capability to describe the premixed layer formation.

System-Level Impingement Cooling with Cryogens

System-level impingement cooling with cryogens has potential thermal applications in size-constrained, weight-constrained, and power-constrained or low-atmosphere environments by utilizing a phase change for enhanced heat transfer at cryogenic temperatures. In this work, an experiment capable of measuring the heat and mass flow of liquid nitrogen jets for variable impingement surface temperatures, mass flow rates, and jet geometries is developed. A boiling curve and other performance metrics are produced. A critical heat flux of approximately is observed.

Swirling supersonic gas flow in an EIGA atomizer for metal powder production: Numerical investigation and experimental validation

This paper is concerned with the modeling of the Electrode Induction Melting Gas Atomization (EIGA) process. This process employs a swirling supersonic inert gas jet to atomize a free-fall molten metal stream, with the aim to produce powders of highly reactive metals. As a first step towards the development of a complete model, this study aims to describe the behavior of the swirling gas flow through and downstream the EIGA gas nozzle and to highlight the influence of the main operating parameters on the jet characteristics. The developed model is based on the Reynolds-Averaged Navier-Stokes (RANS) approach using the Favre decomposition for compressible flow together with a k-ω SST turbulence model. The numerical results are partially validated against images of the gas flow patterns obtained using the Schlieren imaging technique. The simulation results show that the gas flow transits to a supersonic regime immediately before exiting the nozzle. In the atomization tower, it forms a swirling supersonic jet with an asymmetric geometry composed of several Mach diamonds. The inlet gas pressure has a significant effect on the jet structure and Mach number distribution. However, within the investigated range of pressure values (30–45 bar), the swirling motion of the jet, hence the jet geometry, remain little affected. In contrast, a small increase of the nozzle exit slit size significantly increases the swirling motion, which in turn strengthens the jet asymmetry. A reduction of the overpressure in the melting chamber has a similar effect, but to a lesser extent.

Flight-to-Wind-Tunnel Correlation Study using JAXA’s Flying Test Bed “Hisho”

Predicting aircraft flight performance using ground tests is important for development but difficult, and flight-to-wind-tunnel correlation methods have been developed and improved over many years. This paper examines the flight-to-wind-tunnel correlation of the aerodynamic characteristics of the Japan Aerospace Exploration Agency’s (JAXA) “Hisho” Flying Test Bed by applying typical methods to flight test data. It was found that the minimum drag coefficient of a business jet geometry test model follows the gradient of the Schoenherr equation well for forced turbulent flows. After that, the reference condition for the correlation was set, but discrepancies in the lift and drag coefficients remained between the flight and wind tunnel tests. A preliminary study identified force differences parallel to the axis of the engine nacelle as being caused by spillage drag due to the difference in the capture area ratio (CAR) between the flight and wind tunnel tests. However, the test data were insufficient to reasonably attribute the difference in the normal force component to lift yielded by the engine nacelle. This was due to the fact that the flight test parameters showed an interdependency and the effects of relevant parameters were not fully investigated in wind tunnel tests.

Orthogonal Experimental Design Based Nozzle Geometry Optimization for the Underwater Abrasive Water Jet

This paper proposes an orthogonal experimental design based on the optimization method for the nozzle geometry of an underwater abrasive water jet, with the objective of maximizing the cutting capacity and minimizing the nozzle-erosion rate. Parameter effects on the nozzle’s cutting capability and life are analyzed. This analysis shows that while the contraction-section curve, the contraction-section axial length and the focus-section axial length mainly affected the service life of the nozzle, the nozzle-outlet diameter mainly affected the cutting capacity of the nozzle. The effect significances of the structural parameters, from high to low, are outlet diameter &gt; axial length of contraction section &gt; axial length of focusing section &gt; contraction curve. According to the optimal performance index for this nozzle, the optimal nozzle structure parameters were a contraction-section curve of A4 (parabolic), an axial length of contraction section of 20 mm, an outlet diameter of 2 mm, and an axial length focusing section of 10 mm. With the optimal parameters, the nozzle performance excellence index was Q = 1.441, which is the optimization objective and 44.1% higher than the baseline of the conical nozzle; the maximum velocity at a distance of 100 mm was improved by 56% and the maximum erosion rate was reduced by 72% compared to that of the conical nozzle.

Diagnostics of a nanosecond atmospheric plasma jet. Electron and ro-vibrational excitation dynamics

Atmospheric repetitive He discharge with 10 ns current peak width and V s−1 voltage front rise working in jet geometry is studied. The first part of the study is devoted to electrical and optical discharge characterization including voltage-current behavior, emission dynamics, as well as ro-vibrational dynamics of N2, N and OH molecules. It is found that He atoms get excited at the very early stage, as a result of ionization wave formation. This process follows by excitation of O, N2 and N. It is also shown that a rather small (0.1%–1%) air admixtures facilitate gas breakdown, as revealed by shortening of the discharge current risetime. The rotational excitation of N always overtakes He excitation by about 5 ns, with rotational temperature peaking at about 650 K and decaying afterwards, whereas rotational temperature of N2 always remains constant equal to about 300 K. This value is associated with gas kinetic temperature since the electron-rotational (e-R) excitation process is too slow, so it cannot be activated during the plasma phase and no additional change in rotational excitation of N2 happens. Nitrogen molecules remain vibrationally excited in the discharge, post-discharge and jet areas after the plasma pulse which is likely a result of ionization wave propagation. Upon water vapor injection the apparent OH rotational distributions reveal double Boltzmann slope representing thermalized and non-thermalized OH groups. Rotational temperature of the thermalized group correlates with the one of N showing, however, much longer relaxation time, whereas for the non-thermalized group it remains above 1 eV at all conditions. The obtained results confirm that the studied ns- discharge is a good candidate for temperature-sensitive applications, such as the bio-sample treatment. Further analysis related to the ionization waves, electron density and electric field behavior is undertaken in the second part.

Magnetically arrested accretion disks launching structured jets in application to GRB and AGN engines

Context. We explore the formation, energetics, and geometry of relativistic jets along with the variability of their central engine. We study both fast and slowly rotating black holes and address our simulations to active galaxy centers as well as gamma ray burst engines. Aims. The structured jets are postulated to account for emission properties of high energy sources across the mass scale, launched from stellar mass black holes in gamma ray bursts (GRBs) and from supermassive black holes in active galactic nuclei (AGNs). Their active cores contain magnetized accretion disks and the rotation of the Kerr black hole provides a mechanism for launching relativistic jets. This process works most effectively if the mode of accretion turns out to be magnetically arrested. In this mode, the modulation of jets launched from the engine is related to internal instabilities in the accretion flow that operate on smallest time and spatial scales. As these scales are related to the light-crossing time and the black hole gravitational radius, the universal model of jet-disk connection is expected to scale with the mass of the black hole. Methods. We investigated the jet-disk connection by means of 3D general relativistic magneto-hydrodynamical simulations of the magnetically arrested disk accretion in Kerr geometry. We also quantified the variability of the disk by means of a Fourier analysis. Results. We found that the system evolution is governed by the physical parameters of the engine, such as the black hole spin and disk size, as well as disk magnetization, and we applied our scenarios to typical types of sources in AGN and GRB classes. We found that the magnetically arrested disk (MAD) scenario is applicable to AGN engines and supports persistent jet emissions. It can also be applied to GRBs, as it gives the variability pattern roughly consistent with observations. However, in some cases, strong magnetic fields may lead to jet quenching, and this effect is found to be important mainly for GRB jets. We speculate that it may be related to the strength of magnetically driven winds from the GRB engines.

Detection of minute-timescale γ-ray variability in BL Lacertae by Fermi-LAT

BL Lacertae, the prototype of the BL Lacertae (BL Lac) category of blazars, underwent a giant γ-ray flare in April 2021. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (hereafter Fermi-LAT) observed a peak γ-ray (0.1−500 GeV) flux of ∼2 × 10−5 ph cm−2 s−1 within a single orbit on 2021 April 27, which is historically the brightest γ-ray flux ever detected from the source. Here, we report, for the first time, the detection of significant minute-timescale GeV γ-ray flux variability in the BL Lac subclass of blazars by the Fermi-LAT. We resolved the source variability down to two-minute binned timescales with a flux halving time of ∼1 min, which is the shortest GeV variability timescale ever observed from blazars. The detected variability timescale is much shorter than the light-crossing time (∼14 min) across the central black hole of BL Lac, indicating a very compact γ-ray emission site within the outflowing jet. Such a compact emitting region requires the bulk Lorentz factor of the jet to be larger than 16 so that the jet power is not super Eddington. We found a minimum Doppler factor δmin of 15 using the δ function approximation for the γγ opacity constraint. For a conical jet geometry, considering Γ = δmin, the observed short variability timescale for BL Lac suggests that the very compact emission region lies at a distance of about 8.62 × 1014 cm from its central engine.

A Mildly Relativistic Outflow Launched Two Years after Disruption in Tidal Disruption Event AT2018hyz

We present late-time radio/millimeter (as well as optical/UV and X-ray) detections of tidal disruption event (TDE) AT2018hyz, spanning 970–1300 d after optical discovery. In conjunction with earlier deeper limits, including those at ≈700 days, our observations reveal rapidly rising emission at 0.8–240 GHz, steeper than F ν ∝ t 5 relative to the time of optical discovery. Such a steep rise cannot be explained in any reasonable scenario of an outflow launched at the time of disruption (e.g., off-axis jet, sudden increase in the ambient density), and instead points to a delayed launch. Our multifrequency data allow us to directly determine the radius and energy of the radio-emitting outflow, and we find from our modeling that the outflow was launched ≈750 days after optical discovery. The outflow velocity is mildly relativistic, with β ≈ 0.25 and ≈0.6 for a spherical geometry and a 10° jet geometry, respectively, and the minimum kinetic energy is E K ≈ 5.8 × 1049 and ≈6.3 × 1049 erg, respectively. This is the first definitive evidence for the production of a delayed mildly relativistic outflow in a TDE; a comparison to the recently published radio light curve of ASASSN-15oi suggests that the final rebrightening observed in that event (at a single frequency and time) may be due to a similar outflow with a comparable velocity and energy. Finally, we note that the energy and velocity of the delayed outflow in AT2018hyz are intermediate between those of past nonrelativistic TDEs (e.g., ASASSN-14li, AT2019dsg) and the relativistic TDE Sw J1644+57. We suggest that such delayed outflows may be common in TDEs.