Context. Understanding the complex interactions between convection, magnetic fields, and rotation is key to modeling the internal dynamics of the Sun and stars. Under rotational influence, compressible convection forms prograde-propagating convective columns near the equator. The interaction between such rotating columnar convection and the small-scale dynamo (SSD) remains largely unexplored. Aims. We investigate the influence of the SSD on the properties of rotating convection in the equatorial regions of solar and stellar convection zones. Methods. A series of rotating compressible magnetoconvection simulations were performed using a local f -plane box model at the equator. The flux-based Coriolis number, Co * , was varied systematically. To isolate the effects of the SSD, we compared results from hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations. Results. The SSD affects both convective heat and angular momentum transport. In MHD cases, convective velocity decreases more rapidly with increasing Co * than in HD cases. This reduction is compensated for by enhanced entropy fluctuations, maintaining the overall heat transport efficiency. Furthermore, a weakly subadiabatic layer is maintained near the base of the convection zone even under strong rotational influence when the SSD is present. These behaviors reflect a change in the dominant force balance: the SSD introduces a magnetostrophic balance at small scales, while geostrophic balance persists at larger scales. The inclusion of the SSD also reduces the dominant horizontal scale of columnar convective modes by enhancing the effective rotational influence. Regarding angular momentum transport, the SSD generates Maxwell stresses that counteract the Reynolds stresses, thereby quenching the generation of mean shear flows. Conclusions. Small-scale magnetic fields interact nonlinearly with columnar convection and induce substantial modifications in the dynamics of rotating convection. These effects should be accounted for in models of solar and stellar convection.

Accurate mass, momentum, and energy transfer predictions through gas and liquid interfaces are critical in simulating gas–liquid two-phase flow dynamics. Since the interfacial transfer rates depend on the interfacial area concentration (IAC), it is essential to model the IAC accurately for robust two-phase flow analyses. The inverse of the IAC characterizes bubble characteristic length, and thus, the IAC is related to the bubble Sauter mean diameter (SMD). This study proposed a method to use neural networks for systematically developing a one-dimensional SMD correlation, i.e., an IAC correlation for forced convective and bubble columns. First, an extensive literature survey provided 799 data points, consisting of 590 data points in forced convective bubbly flows and 209 in bubble columns. The neural networks were applied to 799 data points to determine the maximum attainable prediction accuracy of the hypothetical SMD correlations. Target mean absolute percentage errors (MAPEs) of 21.2% for IAC and 15.6% for SMD were established. The neural network could identify three critical non-dimensional parameters: liquid fraction, bubble Reynolds number, and viscosity number, enabling the development of the SMD correlation. With void fraction (VF) predicted by the drift-flux correlation, the SMD correlation could be converted to the IAC correlation, i.e., IAC = 6×VF/SMD. The newly developed SMD and IAC correlations demonstrated reliable predictive capabilities. For forced convective bubbly flows, MAPEs were 19.5% for IAC and 16.1% for SMD. For bubble columns, MAPEs were 45.6% for IAC and 26.9% for SMD. Across all of the datasets, the correlation achieved MAPEs of 26.3% for IAC and 19.0% for SMD. The developed correlations were successfully applied to a wide range of flow conditions: channel geometries (medium-to-large circular pipes, rectangular ducts, rod bundles, and annuli); flow directions (upward, downward, and horizontal); gas–liquid systems (air–water, nitrogen–water, and oxygen–sodium sulfite solution); hydraulic diameters (9.0 to 304 mm); and pressures (0.10 to 2.0 MPa).

Abstract Understanding solar turbulent convection and its influence on differential rotation has been a challenge over the past two decades. Current models often overestimate giant convection cells' amplitude, leading to an effective Rossby number (Ro) too large and a shift toward an antisolar rotation regime. This convective conundrum underscores the need for improved comprehension of solar convective dynamics. We propose a numerical experiment in the parameter space that controls Ro while increasing the Reynolds number (Re) and maintaining solar parameters. By controlling the Nusselt number (Nu), we limit the energy transport by convection while reducing viscous dissipation. This approach enabled us to construct a Sun-like rotating model (SBR97n035) with strong turbulence (Re ∼ 800) that exhibits prograde equatorial rotation and aligns with observational data from helioseismology. We compare this model with an antisolar rotating counterpart and provide an in-depth spectral analysis to investigate the changes in convective dynamics. We also find the appearance of vorticity rings near the poles, whose existence on the Sun could be probed in the future. The Sun-like model shows reduced buoyancy over the spectrum, as well as an extended quasi-geostrophic equilibrium toward smaller scales. This promotes a Coriolis–inertia (CI) balance rather than a Coriolis–inertia–Archimedes (CIA) balance, in order to favor the establishment of a prograde equator. The presence of convective columns in the bulk of the convection zone, with limited surface manifestations, also hints at such structures potentially occurring in the Sun.

Intense rainfall events frequently occur in Brazil, often leading to rapid flooding. Despite their recurrence, there is a notable lack of sub-daily studies in the country. This research aims to assess patterns related to the structure and microphysics of clouds driving intense rainfall in Brazil, resulting in high accumulation within 1 h. Employing a 40 mm/h threshold and validation criteria, 83 events were selected for study, observed by both single and dual-polarization radars. Contoured Frequency by Altitude Diagrams (CFADs) of reflectivity, Vertical Integrated Liquid (VIL), and Vertical Integrated Ice (VII) are employed to scrutinize the vertical cloud characteristics in each region. To address limitations arising from the absence of polarimetric coverage in some events, one case study focusing on polarimetric variables is included. The results reveal that the generating system (synoptic or mesoscale) of intense rain events significantly influences the rainfall pattern, mainly in the South, Southeast, and Midwest regions. Regional CFADs unveil primary convective columns with 40–50 dBZ reflectivity, extending to approximately 6 km. The microphysical analysis highlights the rapid structural intensification, challenging the event predictability and the issuance of timely, specific warnings.

Abstract The local scale of rotating convection, ℓ, is a fundamental parameter in many turbulent geophysical and astrophysical fluid systems, yet it is often poorly constrained. Here we conduct rotating convection laboratory experiments analogous to convecting flows in planetary cores and subsurface oceans to obtain measurements of the local scales of motion. Utilizing silicone oil as the working fluid, we employ shadowgraph imagery to visualize the flow, from which we extract values of the characteristic cross‐axial scale of convective columns and plumes. These measurements are compared to the theoretical values of the critical onset length scale, ℓcrit, and the turbulent length scale, ℓturb. Our experimentally obtained length scale measurements simultaneously agree with both the onset and turbulent scale predictions across three orders of magnitude in convective supercriticality , a correlation that is consistent with inferences made in prior studies. We further explore the nature of this correlation and its implications for geophysical and astrophysical systems.

Planetary cores are the seat of rich and complex fluid dynamics, in which the effects of rotation and magnetic field combine. The equilibria governing the strength of the magnetic field produced by the dynamo effect, the organisation and amplitude of the flow, and those of the density field, remain debated despite remarkable progress made in their numerical simulation. This paper describes an approach based on the explicit consideration of the variation of time scales τ with spatial scales ℓ for the different physical phenomena involved. The τ – ℓ diagrams thus constructed constitute a very complete graphic summary of the dynamics of the object under study. We highlight the role of the available convective power in controlling this dynamics, together with the relevant force balance, for which we derive a very telling τ – ℓ translation. Several scenarios are constructed and discussed for the Earth’s core, shedding new light on the width of convective columns, and on the force equilibria to be considered. A QG-MAC scenario adapted from [Aubert, 2019] gives a good account of the observations. A diversion to Venus reveals the subtlety and relativity of the notion of “fast rotator”. We discuss scaling laws and their validity domain, and illustrate “path strategies”. A complete toolbox is provided, allowing everyone to construct a τ – ℓ diagram of a numerical simulation, a laboratory experiment, a theory, or a natural object.

Context. Rotation is thought to influence the size of convective eddies and the efficiency of convective energy transport in the deep convection zones of stars. Rotationally constrained convection has been invoked to explain the lack of large-scale power in observations of solar flows. Aims. Our main aims are to quantify the effects of rotation on the scale of convective eddies and velocity as well as the depths of convective overshoot and subadiabatic Deardorff layers. Methods. We ran moderately turbulent three-dimensional hydrodynamic simulations of rotating convection in local Cartesian domains. The rotation rate and luminosity of the simulations were varied in order to probe the dependency of the results on Coriolis, Mach, and Richardson numbers measuring the influences of rotation, compressibility, and stiffness of the radiative layer. The results were compared with theoretical scaling results that assume a balance between Coriolis, inertial, and buoyancy (Archimedean) forces, also referred to as the CIA balance. Results. The horizontal scale of convective eddies decreases as rotation increases, and it ultimately reaches a rotationally constrained regime consistent with the CIA balance. Using a new measure of the rotational influence on the system, we found that even the deep parts of the solar convection zone are not in the rotationally constrained regime. The simulations captured the slowly and rapidly rotating scaling laws predicted by theory, and the Sun appears to be in between these two regimes. Both the overshooting depth and the extent of the Deardorff layer decrease as rotation becomes more rapid. For sufficiently rapid rotation, the Deardorff layer is absent due to the symmetrisation of upflows and downflows. However, for the most rapidly rotating cases, the overshooting increases again due to unrealistically large Richardson numbers that allow convective columns to penetrate deep into the radiative layer. Conclusions. Relating the simulations with the Sun suggests that the convective scale, even in the deep parts of the Sun, is only mildly affected by rotation and that some other mechanism is needed to explain the lack of strong large-scale flows in the Sun. Taking the current results at face value, the overshoot and Deardorff layers are estimated to span roughly 5% of the pressure scale height at the base of the convection zone in the Sun.

This study focuses on understanding municipal wastewater (MWW) constituents and assessing technological options to harness the energy content of wastewater in developing countries. There are numerous research studies related to water treatment technologies and wastewater energy value. However, it remains to be seen which perspectives actually make technology adoption feasible. This study explores and presents the potential for some viable and innovative MWW treatment plant (WWTP) systems as a paradigm shift towards resource recovery, energy neutrality and the production of renewable energy by WWTPs. Various cost-effective opportunities related to operational strategies, plant redesign and the upgrading of current WWTPs that can foster self-reliant communities were visualised. Thermal and chemical pretreatments, sequential batch reactors, anaerobic membrane fluidised bioreactors, ammonia-based aeration control and combined heat and power systems can collectively contribute to energy recovery by WWTPs, ranging from 85 to 111%. The study suggests that upgrading the system to become an energy self-reliant water treatment system outweighs the multimode costs associated with health and ecological damages by reducing diseases, pollution and poor productivity regimes.

An open-source Finite Element Quench Simulator (FiQuS) is being developed as part of the STEAM framework following CERN's open science policy (CERN, 2022). The tool is based solely on open-source software and uses Python to generate geometries and meshes with Gmsh and compute solutions with GetDP. FiQuS scripts have a modular structure to accommodate a broad range of geometries and simulation requirements, focusing mainly on superconducting accelerator magnets. At its advanced stage, the tool will be capable of 1D, 2D, and 3D geometry generation of superconducting elements such as bus bars, multi-pole, solenoid, and canted-cos-theta (CCT) magnets. It already has the capability for parametrized mesh control and subsequent model generation of 2D multi-pole and 3D CCT magnets. It will be possible to perform either electromagnetic (EM), thermal (TH), or coupled EM-TH simulations for static or transient analysis. The focus is on aspects related to the powering and quench transients, enabling parametric analyses and co-simulations to support comprehensive quench protection studies. In this contribution, we lay the foundation of FiQuS by presenting its structure and three specific capabilities that represent the basis upon which the future modules will be built, mainly: enabling cooperative simulations and the Single Source Of Truth (SSOT) practice; seamlessly integrating magnet design details around a set of input files; enabling parametric analysis and multi-objective optimization with Dakota software developed by Sandia National Laboratories. These capabilities showcase the integration of FiQuS with software developed at CERN, at other national laboratories, and within the STEAM framework.

In this work we study the global solvability of moisture dynamics with phase changes for warm clouds. We thereby in comparison to previous studies (Hittmeir et al. in Nonlinearity 30:3676–3718, 2017) take into account the different gas constants for dry air and water vapor as well as the different heat capacities for dry air, water vapor and liquid water, which leads to a much stronger coupling of the moisture balances and the thermodynamic equation. This refined thermodynamic setting has been demonstrated to be essential, e.g. in the case of deep convective cloud columns in Hittmeir and Klein (Theoret Comput Fluid Dyn 32(2):137–164, 2017). The more complicated structure requires careful derivations of sufficient a priori estimates for proving global existence and uniqueness of solutions.

Increased need for plasmid DNA (pDNA) with sizes above 10kbp (large pDNA) in gene therapy and vaccination brings the need for its large-scale production with high purity. Chromatographic purification of large pDNA is often challenging due to low process yields and column clogging, especially using anion-exchanging columns. The goal of our investigation was to evaluate the mass balance and pDNA isoform composition at column outlet for plasmids of different sizes in combination with weak anion exchange (AEX) monolith columns of varying channel size (2, 3 and 6µm channel size). We have proven that open circular pDNA (OC pDNA) isoform is an important driver of reduced chromatographic performance in AEX chromatography. The main reason for the behaviour is the entrapment of OC pDNA in chromatographic supports with smaller channel sizes. Entrapment of individual isoforms was characterised for porous beads and convective monolithic columns. Convective entrapment of OC pDNA isoform was confirmed on both types of stationary phases. Porous beads in addition showed a reduced recovery of supercoiled pDNA (on an 11.6kbp plasmid) caused by diffusional entrapment within the porous structure. Use of convective AEX monoliths or membranes with channel diameter >3.5µm has been shown to increase yields and prevent irreversible pressure build-up and column clogging during purification of plasmids at least up to 16kbp in size.

Abstract Orographically‐locked diurnal convection involves interactions between local circulation and the thermodynamic environment of convection. Here, the relationships of convective updraft structures over orographic precipitation hotspots and their upstream environment in the TaiwanVVM large‐eddy simulations are analyzed for the occurrence of the orographic locking features. Strong convective updraft columns within heavily precipitating, organized systems exhibit a mass flux profile gradually increasing with height through a deep lower‐tropospheric inflow layer. Enhanced convective development is associated with higher upstream moist static energy (MSE) transport through this deep‐inflow layer via local circulation, augmenting the rain rate by 36% in precipitation hotspots. The simulations provide practical guidance for targeted observations within the most common deep‐inflow path. Preliminary field measurements support the presence of high MSE transport within the deep‐inflow layer when organized convection occurs at the hotspot. Orographically‐locked convection facilitate both modeling and field campaign design to examine the general properties of active deep convection.

The aim was to study the quality stability of a high-pressure (HP) processed avocado puree-based smoothie beverage and to determine its shelf life. To achieve this mathematical description of HP process parameters (pressure, temperature, and pH conditions) on polyphenoloxidase (PPO) inactivation of avocado-puree (base of the smoothie beverage), use of the appropriate kinetic models was undertaken. Inactivation rate constants were obtained for combinations of constant pressure (600, 700, 750 MPa) and temperature (25, 35, 45 °C) for pH values 4 and 5. According to the Eyring and Arrhenius equations, activation volumes and activation energies, respectively, representing pressure and temperature dependence of the inactivation rate constant, were calculated for all temperatures and pressures studied. The combined use of HP led to PPO inactivation (<10% remaining PPO activity). An increase in the temperature at pressure 600 or 750 MPa caused an increase in PPO inactivation (4.5 and 9.0%, respectively). The ultimate goal was to produce a HP processed avocado puree-based smoothie beverage (containing acid whey and other ingredients) with superior quality and increased shelf life (under refrigeration). The blended ingredients were HP processed in PET packages (600 MPa-25 °C-10 min, 600 MPa-35 °C-10 min, 750 MPa-25 °C-5 min, 750 MPa-35 °C-5 min) based on PPO inactivation as well as industrial practices. Non-processed as well as thermally (TM) processed (90 °C-5 min) samples were used as control samples. No significant differences were found in sensorial attributes between non-processed and HP samples, although the aroma and acceptability scores decreased significantly for thermally pasteurized smoothies. Based on the data obtained, 600 MPa-25/35 °C-10 min are sufficient to obtain safe smoothies (of pH 5 approximately) (up to 6 months) whose organoleptic properties are equally as acceptable to consumers as freshly made smoothies.

Context. The dissipation of tidal inertial waves in planetary and stellar convective regions is one of the key mechanisms that drive the evolution of star–planet and planet–moon systems. This dissipation is particularly efficient for young low-mass stars and gaseous giant planets, which are rapid rotators. In this context, the interaction between tidal inertial waves and turbulent convective flows must be modelled in a realistic and robust way. In the state-of-the-art simulations, the friction applied by convection on tidal waves is commonly modeled as an effective eddy viscosity. This approach may be valid when the characteristic length scales of convective eddies are smaller than those of the tidal waves. However, it becomes highly questionable in the case where tidal waves interact with potentially stable large-scale vortices such as those observed at the poles of Jupiter and Saturn. The large-scale vortices are potentially triggered by convection in rapidly-rotating bodies in which the Coriolis acceleration forms the flow in columnar vortical structures along the direction of the rotation axis. Aims. We investigate the complex interactions between a tidal inertial wave and a columnar convective vortex. Methods. We used a quasi-geostrophic semi-analytical model of a convective columnar vortex, which is validated by numerical simulations. First, we carried out linear stability analysis using both numerical and asymptotic Wentzel–Kramers–Brillouin–Jeffreys (WKBJ) methods. We then conducted linear numerical simulations of the interactions between a convective columnar vortex and an incoming tidal inertial wave. Results. The vortex we consider is found to be centrifugally stable in the range –Ωp ≤ Ω0 ≤ 3.62Ωp and unstable outside this range, where Ω0 is the local rotation rate of the vortex at its center and Ωp is the global planetary (stellar) rotation rate. From the linear stability analysis, we find that this vortex is prone to centrifugal instability with perturbations with azimuthal wavenumbers m = {0,1, 2}, which potentially correspond to eccentricity, obliquity, and asynchronous tides, respectively. The modes with m > 2 are found to be neutral or stable. The WKBJ analysis provides analytic expressions of the dispersion relations for neutral and unstable modes when the axial (vertical) wavenumber is sufficiently large. We verify that in the unstable regime, an incoming tidal inertial wave triggers the growth of the most unstable mode of the vortex. This would lead to turbulent dissipation. For stable convective columns, the wave-vortex interaction leads to the mixing of momentum for tidal inertial waves while it creates a low-velocity region around the vortex core and a new wave-like perturbation in the form of a progressive wave radiating in the far field. The emission of this secondary wave is the strongest when the wavelength of the incoming wave is close to the characteristic size (radius) of the vortex. Incoming tidal waves can also experience complex angular momentum exchanges locally at critical layers of stable vortices. Conclusions. The interaction between tidal inertial waves and large-scale coherent convective vortices in rapidly-rotating planets (stars) leads to turbulent dissipation in the unstable regime and complex behaviors such as mixing of momentum and radiation of new waves in the far field or wave-vortex angular momentum exchanges in the stable regime. These phenomena cannot be modeled using a simple effective eddy viscosity.

UAV-based multispectral and thermal cameras to predict soil water content – A machine learning approach

Abstract Fire-generated tornadic vortices (FGTVs) linked to deep pyroconvection, including pyrocumulonimbi (pyroCbs), are a potentially deadly, yet poorly understood, wildfire hazard. In this study we use radar and satellite observations to examine three FGTV cases during high-impact wildfires during the 2020 fire season in California. We establish that these FGTVs each exhibit tornado-strength anticyclonic rotation, with rotational velocity as strong as 30 m s−1 (60 kt), vortex depths of up to 4.9 km AGL, and pyroCb plume tops as high as 16 km MSL. These data suggest similarities to EF2+ strength tornadoes. Volumetric renderings of vortex and plume morphology reveal two types of vortices: embedded vortices anchored to the fire and residing within high-reflectivity convective columns and shedding vortices that detach from the fire and move downstream. Time-averaged radar data further show that each case exhibits fire-generated mesoscale flow perturbations characterized by flow splitting around the fire’s updraft and pronounced flow reversal in the updraft’s lee. All the FGTVs occur during deep pyroconvection, including pyroCb, suggesting an important role of both fire and cloud processes. The commonalities in plume and vortex morphology provide the basis for a conceptual model describing when, where, and why these FGTVs form.

The geomagnetic field is among the most striking features of the Earth. By far the most important ingredient of it is generate in the fluid conductive outer core and it is known as the main field. It is characterized by a strong dipolar component as measured on the Earth’s surface. It is well established the fact that the dipolar component has reversed polarity many times, a phenomenon dubbed as dipolar field reversal (DFR). There have been proposed numerous models focused on describing the statistical features of the occurrence of such phenomena. One of them is the domino model, a simple toy model that despite its simplicity displays a very rich dynamic. This model incorporates several aspects of the outer core dynamics like the effect of rotation of Earth, the appearance of convective columns which create their own magnetic field, etc. In this paper we analyse the phase space of parameters of the model and identify several regimes. The two main regimes are the polarity changing one and the regime where the polarity remains the same. Also, we draw some scaling laws that characterize the relationship between the parameters and the mean time between reversals (mtr), the main output of the model.

The eccentric dipole (ED) is the next approach of the geomagnetic field after the generally used geocentric dipole. Here, we analyzed the evolution of the ED during extreme events, such as the Matuyama-Brunhes polarity transition (~780 ka), the Laschamp (~41 ka) and Mono Lake (~34 ka) excursions, and during the time of two anomalous features of the geomagnetic field observed during the Holocene: the Levantine Iron Age Anomaly (LIAA, ~1000 BC) and the South Atlantic Anomaly (SAA, analyzed from ~700 AD to present day). The analysis was carried out using the paleoreconstructions that cover the time of the mentioned events (IMMAB4, IMOLEe, LSMOD.2, SHAWQ-Iron Age, and SHAWQ2k). We found that the ED moves around the meridian plane of 0–180° during the reversal and the excursions; it moves towards the region of the LIAA; and it moves away from the SAA. To investigate what information can be extracted from its evolution, we designed a simple model based on 360-point dipoles evenly distributed in a ring close to the inner core boundary that can be reversed and their magnitude changed. We tried to reproduce with our simple model the observed evolution of the ED, and the total field energy at the Earth’s surface. We observed that the modeled ED moves away from the region where we set the dipoles to reverse. If we consider that the ring dipoles could be related to convective columns in the outer core of the Earth, our simple model would indicate the potential of the displacement of the ED to give information about the regions in the outer core where changes start for polarity transitions and for the generation of important anomalies of the geomagnetic field. According to our simple model, the regions in which the most important events of the Holocene occur, or in which the last polarity reversal or excursion begin, are related to the regions of the Core Mantle Boundary (CMB), where the heat flux is low.

Direct numerical simulations are employed to reveal three distinctly different flow regions in rotating spherical Rayleigh‐Bénard convection. In the high‐latitude region I vertical (parallel to the axis of rotation) convective columns are generated between the hot inner and the cold outer sphere. The mid‐latitude region II is dominated by vertically aligned convective columns formed between the Northern and Southern hemispheres of the outer sphere. The diffusion‐free scaling, which indicates bulk‐dominated convection, originates from this mid‐latitude region. In the equator region III, the vortices are affected by the outer spherical boundary and are much shorter than in region II.

With increasing growth of industrial units in developing countries and pollutants produced by these units, nowadays distribution and dispersion modelling of atmosphere pollutants especially in urban areas is an inevitable importance. Dispersion modelling of atmosphere pollutants is a methodology to estimate focus and concentration values of pollutants related to emission source in different seasons. In current study, using numerical analysis, a thermal diffusion of flare and focus values of industrial pollutants simulation using air zonal methodology has been presented. After studying pollutants emission in open area, validation has been done using laboratory data results and computational fluid dynamics method. The results of this study indicate the ability of presented air zonal methodology to predict thermal diffusion of flare and distribution concentration of pollutant source and information gained from this analysis. Then an exploration of effective parameters in pollution emission such as wind velocity, flare height, and pollution emission rate in downstream has been done. As the results show, when wind velocity rises by 130%, pollution will reach far away from production source and with increase in flare height by 25%, the pollution concentration values on the ground has been reduced by 44%. Also with addition of barrier in pollution dispersion path, pollution level will increase by 60%.