Low-frequency Turbulence Research Articles

Juno Plasma Wave Observations at Ganymede.

The Juno Waves instrument measured plasma waves associated with Ganymede's magnetosphere during its flyby on 7 June, day 158, 2021. Three distinct regions were identified including a wake, and nightside and dayside regions in the magnetosphere distinguished by their electron densities and associated variability. The magnetosphere includes electron cyclotron harmonic emissions including a band at the upper hybrid frequency, as well as whistler-mode chorus and hiss. These waves likely interact with energetic electrons in Ganymede's magnetosphere by pitch angle scattering and/or accelerating the electrons. The wake is accentuated by low-frequency turbulence and electrostatic solitary waves. Radio emissions observed before and after the flyby likely have their source in Ganymede's magnetosphere.

Buffeting response of a suspension bridge based on the 2D rational function approximation model for self-excited forces

In the last thirty years, the aerodynamic nonlinearities related to the slow variation of the angle of attack produced by large-scale atmospheric turbulence and their impact on the buffeting response of long-span suspension bridges have been a hot topic in wind engineering research. Self-excited forces accounting for such an effect of turbulence have been crucial in predicting the dynamic response of bridge sectional models subjected to multi-harmonic gusts. In contrast, only few studies on full suspension bridges in realistic turbulent flows are available. To fill this gap, the 2D RFA model for self-excited forces, recently developed and experimentally validated by the authors, in this paper is incorporated into a stochastic time-variant state-space framework to assess the nonlinear buffeting response of a suspension bridge. The most important feature of this model is the modulation of the self-excited forces due to the spatio-temporal fluctuation of the angle of attack produced by low-frequency turbulence. Moreover, the nonlinear external buffeting forces are formulated to achieve a reasonable compromise between the conflicting needs of modelling both nonlinear and unsteady effects of wind velocity fluctuations. The model is applied to the Hardanger Bridge in Norway, considering different wind conditions. Indeed, the aerodynamic derivatives of this bridge deck cross-section present a strong dependence on the mean angle of attack. The results emphasise the significant impact on the buffeting response and flutter stability of considering time-variant self-excited forces, though in specific cases the classical time-invariant approach is found to provide accurate predictions of the bridge vibrations. Finally, the paper investigates the sensitivity of the response statistics to the model cut-offs used to separate the low-frequency and the high-frequency turbulence bands.

High-frequency heating of the solar wind triggered by low-frequency turbulence

The fast solar wind’s high speeds and non-thermal features require that considerable heating occurs well above the Sun’s surface. Two leading theories seem incompatible: low-frequency ‘Alfvénic’ turbulence, which transports energy outwards and is observed ubiquitously by spacecraft but seems insufficient to explain the observed dominance of ion over electron heating; and high-frequency ion-cyclotron waves, which explain the non-thermal heating of ions but lack an obvious source. Here we argue that the recently proposed ‘helicity barrier’ effect, which limits electron heating by inhibiting the turbulent cascade of energy to the smallest scales, can unify these two paradigms. Our six-dimensional simulations show how the helicity barrier causes the large-scale energy to grow through time, generating small parallel scales and high-frequency ion-cyclotron-wave heating from low-frequency turbulence, while simultaneously explaining various other long-standing observational puzzles. The predicted causal link between plasma expansion and the ion-to-electron heating ratio suggests that the helicity barrier could contribute to key observed differences between fast and slow wind streams.

Turbulence in the Sub-Alfvénic Solar Wind

Abstract The Parker Solar Probe (PSP) entered a region of sub-Alfvénic solar wind during encounter 8, and we present the first detailed analysis of low-frequency turbulence properties in this novel region. The magnetic field and flow velocity vectors were highly aligned during this interval. By constructing spectrograms of the normalized magnetic helicity, cross-helicity, and residual energy, we find that PSP observed primarily Alfvénic fluctuations, a consequence of the highly field-aligned flow that renders quasi-2D fluctuations unobservable to PSP. We extend Taylor’s hypothesis to sub- and super-Alfvénic flows. Spectra for the fluctuating forward and backward Elsässer variables ( z ±, respectively) are presented, showing that z + modes dominate z − by an order of magnitude or more, and the z + spectrum is a power law in frequency (parallel wavenumber) f −3/2 ( k ∥ − 3 / 2 ) compared to the convex z − spectrum with f −3/2 ( k ∥ − 3 / 2 ) at low frequencies, flattening around a transition frequency (at which the nonlinear and Alfvén timescales are balanced) to f −1.25 at higher frequencies. The observed spectra are well fitted using a spectral theory for nearly incompressible magnetohydrodynamics assuming a wavenumber anisotropy k ⊥ ∼ k ∥ 3 / 4 , that the z + fluctuations experience primarily nonlinear interactions, and that the minority z − fluctuations experience both nonlinear and Alfvénic interactions with z + fluctuations. The density spectrum is a power law that resembles neither the z ± spectra nor the compressible magnetic field spectrum, suggesting that these are advected entropic rather than magnetosonic modes and not due to the parametric decay instability. Spectra in the neighboring modestly super-Alfvénic intervals are similar.

A new experimental-numerical approach to estimate peak wind loads on roof-mounted photovoltaic systems by incorporating inflow turbulence and dynamic effects

Building appurtenances, such as rooftop photovoltaic (PV) systems, are vulnerable to damage during extreme wind events. To have more robust designs of PV systems, improved estimation of the peak wind effects is deemed necessary. The overall aim of this research is to develop a method for predicting peak wind loads on PV panels, including dynamic effects. For predicting peak pressures on roofs, the Partial Turbulence Simulation (PTS) method has been previously developed to allow for large-scale model testing by analytically incorporating the effects of the missing low-frequency turbulence based on the quasi-steady aerodynamic theory. The current paper focuses on a new experimental-numerical methodology by advancing the PTS approach to account for the dynamic amplification effects of rooftop PV systems. This is accomplished by mathematically applying a gust transfer function and a mechanical admittance function. The proposed advanced PTS approach is demonstrated using full- and small-scale wind tunnel testing of a PV panel mounted at different locations on the roof of a low-rise building with various tilt angles. The peak net force coefficients obtained from experimental testing of the PV panel were compared with those found in ASCE 7-16. Results showed that the ASCE 7-16 values, which currently do not take into consideration the wind-induced dynamic effects on rooftop PV systems, were significantly lower than the estimated peak force coefficients from the current study. This research describes a methodology for predicting peak wind loads on dynamically sensitive building appurtenances that can be used to inform wind load provisions in standards.

Weak magnetohydrodynamic turbulence

Low-frequency hydromagnetic turbulence is thought to play an important role in charged particle energization in space and astrophysical environments. For understanding large-scale turbulence in magnetized plasmas, low-frequency electromagnetic turbulence has been widely investigated within the theoretical framework of incompressible magnetohydrodynamic (MHD) theory. Among the existing works is the weak turbulence formalism of incompressible MHD turbulence. The present paper revisits the existing formalism under the assumption of zero residual energy. Under the strict assumption of turbulence taking place in a two-dimensional plane, which can be interpolated to a three-dimensional situation with azimuthal symmetry, the well-known steady-state turbulent spectrum of k⊥−2 is recovered, where k⊥ denotes the wave number perpendicular to the ambient magnetic field.

Turbulence transport in the solar corona: Theory, modeling, and Parker Solar Probe

A primary goal of the Parker Solar Probe (PSP) Mission is to answer the outstanding question of how the solar corona plasma is heated to the high temperatures needed for the acceleration of the solar wind. Various heating mechanisms have been suggested, but one that is gaining increasing credence is associated with the dissipation of low frequency magnetohyrodynamic (MHD) turbulence. However, the MHD turbulence models come in several flavors: one in which outwardly propagating Alfvén waves experience reflection from the large-scale flow and density gradients associated with the solar corona, and the resulting counterpropagating Alfvén waves couple nonlinearly to produce quasi-2D turbulence that dissipates and heats the corona, thereby driving the solar wind. The second approach eschews a dominant outward flux of Alfvén waves but argues instead that quasi-2D turbulence dominates the lower coronal plasma and is generated in the constantly upwelling magnetic carpet, experiencing dissipation as it is advected through the corona and into the solar wind, yielding temperatures in the corona that exceed a million degrees. We review the two turbulence models, describe the modeling that has been done, and relate PSP observations to the basic predictions of both models. Although PSP measurements are made in the super-Alfvénic solar wind, the observations are close to the coronal region, thus providing a glimpse into the likely properties of coronal turbulence. Observations of low-frequency MHD turbulence by PSP in the super-Alfvénic solar wind allow us to place constraints on models of the turbulently heated solar corona that drive the supersonic solar wind.

Experimental investigation of the effects of length-to-diameter ratio of hot-wire sensor on the dynamic response to velocity fluctuations

This paper reconsidered the criterion on the length-to-diameter ratio (l/d) of the hot-wire sensor, $$l/d \ge 200$$ , for end-conduction effects on the dynamic response of constant-temperature hot-wire anemometer (CTA) to be neglected. Experiments were first conducted using a low-noise compact CTA with hot-wire sensors of l/d = 80, 120, 150 and 200 in a two-dimensional (2-D) circular cylinder wake at a Reynolds number Re = 77, at which a 2-D von Karman vortex street developed, allowing us to exclude spatial filtering and tangential velocity effects. The damping coefficient in the CTA bridge was tuned to 0.70 for all sensors to reduce possible influences of over- or under-damping on measurements in a frequency range up to 6 kHz. The stubs and prongs of probes consisted of identical materials and dimensions so that the thermal properties were considered to be identical for all probes. Careful comparisons of the amplitudes of the fundamental (1.9 kHz) and higher harmonic components of time-periodic wake vortices showed that the attenuation due to the end-conduction effect in the absence of the spatial filtering and damping coefficient effects was at most 2.5% in terms of the rms value of velocity fluctuations even for l/d = 80. The similar weak attenuation (about 2.6% for l/d = 80) was also observed in the measurements of low-frequency free-stream turbulence. In addition, effects of l/d on the yaw angle response of the sensor were examined in the free stream, revealing that the yaw angle ( $$\psi $$ ) variation of the measured velocity (both the mean and fluctuations) obeyed the cosine law for $$\psi \le 60^\circ $$ . The Champagne constant k was 0.12 for l/d = 200 and 0.2 even for l/d = 80 in the mean velocity measurement using the present probe with long stubs. On the other hand, the intensity of free stream turbulence measured using a $$45^\circ $$ -yawed sensor was significantly affected by the sensor’s l/d; the rms value of velocity fluctuation was attenuated by about 7.5% for l/d = 80.

Shear-driven Transition to Isotropically Turbulent Solar Wind Outside the Alfvén Critical Zone

Abstract Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic “flocculated” fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfvén critical zone, and in the vicinity of the first surface, is powered by the relative velocities of adjacent coronal magnetic flux tubes. We suggest that large-amplitude flow contrasts are magnetically constrained at lower altitude but shear-driven dynamics are triggered as such constraints are released above the Alfvén critical zone, as suggested by global magnetohydrodynamic (MHD) simulations that include self-consistent turbulence transport. We argue that this dynamical evolution accounts for features observed by Parker Solar Probe (PSP) near initial perihelia, including magnetic “switchbacks,” and large transverse velocities that are partially corotational and saturate near the local Alfvén speed. Large-scale magnetic increments are more longitudinal than latitudinal, a state unlikely to originate in or below the lower corona. We attribute this to preferentially longitudinal velocity shear from varying degrees of corotation. Supporting evidence includes comparison with a high Mach number three-dimensional compressible MHD simulation of nonlinear shear-driven turbulence, reproducing several observed diagnostics, including characteristic distributions of fluctuations that are qualitatively similar to PSP observations near the first perihelion. The concurrence of evidence from remote sensing observations, in situ measurements, and both global and local simulations supports the idea that the dynamics just above the Alfvén critical zone boost low-frequency plasma turbulence to the level routinely observed throughout the explored solar system.

Edge turbulence characteristics and transport during the ELM mitigation with n = 1 resonant magnetic perturbation on EAST

The edge localized mode (ELM) has been mitigated by n = 1 resonant magnetic perturbation (RMP) in EAST tokamak. The turbulence characteristics and transport during the ELM mitigation have been measured by a series of diagnostics. The edge coherent mode (ECM) with a frequency about 25 kHz almost disappears when ELM is mitigated. The scrape-off layer (SOL) radial turbulent transport is measured by a four-tip Langmuir probe mounted on the manipulator at the outer midplane, exhibiting a strong enhancement of outward particle during the ELM mitigation in the SOL region (3–25 mm outside the LCFS). This enhanced outward radial transport is mainly driven by the low frequency turbulence (< 50 kHz), and is compared with the particle flux deposited on divertor targets quantitatively, revealing a good agreement with each other. It is suggested that a new channel for particle exhaust induced by the low frequency turbulence is beneficial to maintain the ELM mitigation by RMP.

Influence of Rotating Wheels and Moving Ground Use on the Unsteady Wake of a Small-Scale Road Vehicle

New insights into how different ground simulation methods affect road vehicle aerodynamics are presented. Experiments are conducted on a 1/24th-scale model, representative of a Heavy Goods Vehicle, at a Reynolds number, based on width of 2.3 × 105. Particular focus lay in characterising differences in unsteady wake development, with mean drag, base pressures, and wake velocities quantified, compared, and evaluated. Distinctly, these tests include the effects of elevated blockage ratio and wheel rotation. Results show moving ground use can have a substantial influence under these conditions, with increases in wake length and average base pressure coefficient of 17% and 9%, respectively. The dominant wake dynamics, characterised by a global streamwise oscillation commonly referenced as the bubble pumping mode, was also found dependent with asymmetric shedding frequencies from both vertical and horizontal base edges higher with static ground use. For these conditions, development of a low-frequency turbulence source, near omni-directional in nature, positioned behind the model, further contaminates the flow-field. This feature disappears with moving ground use. Both the nature and characteristics of the turbulence generated behind the wheels were also found to evolve differently, with a moving ground promoting stronger and more defined oscillatory behaviour up to model mid-height, two-and-a-half widths downstream. Overall, these results highlight that while variations in time-independent quantities to differing ground simulation can often be very subtle, prompting the interpretation of negligible overall effects, in-depth consideration from a time-dependent perspective may lead to a different conclusion.

Effect of the low-frequency turbulence on the aeroelastic response of a long-span bridge in wind tunnel

The influence of the low frequency turbulence components on the buffeting response of long span bridges was studied through experimental tests performed on a full bridge aeroelastic model in the wind tunnel of the Politecnico di Milano, using an active turbulence generator producing a correlated deterministic harmonic turbulence. The experimental evidence underlined the nonlinear effect of the low frequency incoming turbulence on the dynamic resonant response of the structure at higher frequencies.Numerical simulations are used to explain the bridge behavior considering the variation of the aeroelastic properties of the bridge with the instantaneous angle of attack and reduced velocity. Even though wind tunnel experiment uses an oversimplified wind spectrum with an intentionally high correlation along the main span, it helps to understand the nonlinear interaction between the low frequency and the high frequency buffeting response on a full bridge.

P93 The usefulness of dual cardiac autonomic nervous modulation assessment for prediction of mortality in patients with relatively preserved left ventricular ejection fraction

Abstract Background Recent guidelines have stated that reduced left ventricular ejection fraction (LVEF) is the gold standard marker for identifying patients at risk for cardiac mortality. Although reduced LVEF identifies patients at an increased risk of cardiac arrest, sudden cardiac deaths (SCDs) occur considerably more often in patients with relatively preserved LVEF. Current guidelines on SCDs risk stratification do not adequately cover this general population pool. Heart rate variability (HRV) and heart rate turbulence (HRT) are non-invasive electrocardiography (ECG)-based techniques capable of providing relevant information on the cardiac autonomic nervous modulation. Although a large body of evidence about autonomic nervous modulation markers has been reported, the usefulness of HRV and HRT parameters for risk stratification in such patients with relatively preserved LVEF has not yet been elucidated. Purpose This study aimed to evaluate HRV and HRT parameters for predicting cardiac mortality in patients with structural heart disease (SHD), including ischemic heart disease, dilated cardiomyopathy and valvular heart disease, who have mid-range left ventricular dysfunction (LVD). Methods We prospectively enrolled 229 patients (187 men, age 63 ± 13 years) with SHD who have mid-range LVD (LVEF &amp;gt; 40%). HRV and HRT parameters based on 24-hour ambulatory ECG recordings (Fukuda Denshi Co., Ltd., Tokyo, Japan) were evaluated as follows; SDNN, triangular index, high and low frequency HRV, turbulence onset and slope. The primary endpoint was all-cause mortality. Univariate and multivariate Cox regression analysis were used to assess the association between these cardiac autonomic nervous modulation and mortality. Results During a mean follow-up of 21 ± 11 months, all-cause mortality was seen in 11 (4.8%) patients. Univariate Cox regression analysis showed that reduced SDNN (&amp;lt;50ms), reduced triangular index (&amp;lt;20ms) and HRT category 2 were significantly associated with the primary endpoint (P &amp;lt; 0.05). When HRT category 2 combined with reduced SDNN, Multivariate Cox regression analysis revealed that this combination more strongly associates with the primary endpoint (hazard ratio =7.91, 95%CI, 1.82-34.2; P = 0.006). Conclusion Dual cardiac autonomic nervous modulation assessment which combined HRT and HRV could be a superior technique to predict mortality in patients with relatively preserved LVEF.

Test particle dynamics in low-frequency tokamak turbulence

We study the evolution of one million test particles in a turbulent plasma simulation, using the gyrokinetic code Trapped Element REduction in Semi-Lagrangian Approach (TERESA), as a method to get insights into the type of transport governing the plasma. TERESA (Trapped Element REduction in Semi-Lagrangian Approach) is a collisionless global 4D code which treats the trapped particles kinetically, while the passing particles are considered adiabatic. The Vlasov-Poisson system of equations is averaged over the cyclotron and the trapped particle's bounce motion, and thus, the model focuses on slow phenomena of the order of the toroidal precession motion of the banana orbits. We initialize the test particles, which are de facto “test banana-centers,” at a time of the simulation when the plasma is turbulent. We impose an initial temperature and density gradients, and only the Trapped Ion Mode (TIM) instability can develop in this system. We then calculate the Mean Squared Displacement of the test particles as a function of time in order to obtain a random walk diffusion coefficient. We observe that the radial diffusion of the test particles depends on their toroidal precession kinetic energy (E), in such a way that the transport of particles is dominated by a strong, relatively narrow peak at the resonant energies. A radial particle diffusion flux is then calculated and compared to the total radial particle flux accounting for all the transport processes such as diffusion and advection which is obtained directly from the TERESA code. We can thus compare the diffusive contribution to the particle flux against the nondiffusive contributions. The results show that the total flux is essentially diffusive which is consistent with our simulation setup aiming for “global turbulence.” Both fluxes present a peak around a resonance energy ER≈1.74Ti between the TIM and the particles. Both thermal and high-energy particles do not contribute significantly to radial transport.

An experimental investigation of blob behaviors in lower hybrid wave dominant heating scenarios on EAST

Systematic measurements on scrape-off layer (SOL) blob behaviors have been performed by lithium beam emission spectroscopy on EAST in lower hybrid wave (LHW) heating dominant low confinement (L-mode) discharges. With the application of LHW, blob fluctuation amplitude and associated blob radial transport flux are profoundly suppressed. The reductions of the blob amplitude and transport flux are concomitant with the increase of SOL poloidal velocity and Er×B flow shear. Meanwhile, the blob eddy is strongly tilted and the radial correlation length is reduced. All the measurements point toward the important influences of the LHW induced Doppler shift effect and Er×B flow shear on the suppression of blobs and low frequency turbulence.

Evolution of turbulence in a wind turbine flow field with a neutral atmospheric boundary layer and an analysis of the blade root load

In this study, a neutral atmospheric boundary layer and wind turbine blades were constructed in a large eddy simulation and actuator line model for conducting a field experiment of a wind turbine. Further, the flow field of the wind turbine was simulated in a neutral atmospheric boundary layer. The evolution of the turbulence in the front and back of the rotor with a neutral atmospheric boundary layer and its correlation with the load were studied by analyzing the continuous wavelets, the spectrum, and the correlation. The results indicate that the coherent structure of the turbulence in the neutral atmospheric boundary layer becomes stronger from one-diameter (1 D ) front of the rotor plane to 1 D back of it. The coherent structure of the turbulence in inflow is affected by the rotation of the rotor. Subsequently, strong small-scale turbulence structures appear in the rotor plane, which are continuously dissipated in the wind direction. The turbulent energy with small scales at 1 D back of rotor is feeble, and the turbulence mainly moves on a large scale. The frequency of the small-scale turbulence is approximately 1.82 Hz at the tip, which corresponds to the passing frequency of the blade and is mainly generated because of the rotation of the rotor. The flapwise load of the blade root is high when the turbulent energy is high. The results of wavelet analysis denote that the turbulence structure at the monitoring points has a good relation with the flapwise load of the blade root, and the flapwise load of the blade root of the wind turbine has obvious response to the turbulent structure of the atmosphere. A multi-resolution analysis of two points at the center and tip of the rotor and the flapwise load of the blade root denotes that the low-frequency turbulent structure at the center of the rotor (B3–B6 frequency band) is dependent on the low-frequency flapwise load of the blade root, whereas the high-frequency turbulent structure (B1–B2 frequency band) has no obvious corresponding relation with the flapwise load of the blade root. The high-frequency turbulent structure at the tip (B1–B2 frequency band) is related to the high-frequency flapwise load of the blade root, whereas the low-frequency turbulent structure (B3–B6 frequency band) has no obvious corresponding relation with the flapwise load of the blade root. Therefore, the low-frequency turbulence structure significantly influences the low-frequency band of the flapwise load of the blade root, whereas the high-frequency turbulence structure significantly influences the high-frequency band of the flapwise load of the blade root. When compared with the high-frequency turbulent structure at the blade root, the high-frequency turbulent structure has a higher frequency and a higher energy at the blade tip, and its influence on the high-frequency band of the flapwise load of the blade root is more obvious, exhibiting a consistent regular periodic variation.

Study of electromagnetic mode contributing inward particle pinch in the scrape-off layer during H-mode discharge

With the application of a four-tip Langmuir probe, the anomalous transport contributed by the turbulence and its impact on particle decay length in the scrape-off layer (SOL) has been studied on HL-2A tokamak. A high-frequency electromagnetic mode (HFM, 100 kHz < fHFM < 400 kHz) is reported, which can both be observed in the pedestal region and the SOL during the type-III ELMy H-mode discharge. In SOL, the HFM propagates in the electron diamagnetic direction in both the laboratory frame (22 km s−1) and plasma frame (24 km s−1) with m ≃ 28, n ∼ 8 and kθ ρi ∼ 0.04. Direct measurement shows that the HFM can drive inward particle flux, which can be explained by the electron diamagnetic rotation of the HFM. The time evolutions of particle flux driven by the low frequency turbulence (LFT, ‘blobby’ structures) and the HFM as well as the typical decay length of divertor particle flux suggest that the decay length in SOL can both be modified by the outward particle transport of the ‘blobby’ structures (Γr,LFT, <40 kHz) and inward particle transport by the HFM (Γr,HFM). The decay length of the particle flux is mostly suppressed when a significant inward flux by the HFM bursts under the condition of a low-level outward flux by ‘blobby’ events, suggesting the important role of anomalous transport on the decay length in the SOL.

Research on the Loads of NREL 5MW Wind Turbine under Stable Atmospheric Conditions

To study how the atmospheric turbulence affects the wind turbine, blade element momentum theory coupled with harmony superposition method was used to study the loads of NREL 5MW wind turbine based on the standard Von Karman spectrum and NWTC measured spectra with different atmospheric stability. The results show that the standard Von Karman spectrum overestimates power and thrust relative to NWTC spectrum. From a frequency domain perspective, there is a critical frequency linearly related to the tip speed ratio, which determines the range of turbulence scales that can affect the wind turbine. The wind-turbine loads are mainly affected by the low-frequency turbulent structure in the flow below the critical frequency and decoupled from the flow above the critical frequency. From an intuitive perspective, the low-frequency turbulence structure can’t be effectively absorbed by the rotor, but is transformed into fatigue loads by the structure.

GDB: A global 3D two-fluid model of plasma turbulence and transport in the tokamak edge

The global drift-ballooning (GDB) code is developed to study tokamak edge low frequency turbulence and transport, and their relationship to global profile evolution. The code employs a 3D electromagnetic fluid model that does not discriminate between equilibrium and perturbative contributions, capturing arbitrary amplitude fluctuations. Primitive plasma variables, including the E×B flow profiles, are evolved self-consistently in both closed-flux surfaces and the scrape-off-layer (SOL). A suite of numerical techniques described here handle the linear and non-linear components of the model efficiently so as to support realistic discharge parameters (such as realistic deuterium mass ratio mi∕me≈60) and yield good scaling on high performance computing (HPC) systems. GDB resolves turbulence slower than the ion gyrofrequency in simulations that capture the millisecond-scale evolution of global plasma profiles.

Gyrofluid vortex interaction

Low-frequency turbulence in magnetised plasmas is intrinsically influenced by gyroscale effects across ion Larmor orbits. Here we show that fundamental vortex interactions like merging and co-advection in gyrofluid plasmas are essentially modified under the influence of gyroinduced vortex spiraling. For identical initial vorticity, the fate of co-rotating eddies is decided between accelerated merging or explosion by the asymmetry of initial density distributions. Structures in warm gyrofluid turbulence are characterised by gyrospinning enhanced filamentation into thin vorticity sheets.