Flow Speed Research Articles

Flow pattern, particle capture and contractile behaviour in the demosponge Halichondria panicea

ABSTRACT In the aquiferous system of demosponges, the flow into inhalant canals is driven by the beating flagella of the choanocytes organized in chambers imbedded in the walls and the filtered water is discharged into exhalant canals. Our aim was to characterize the laminar flow pattern and fate of captured algal cells and microplastic beads in the inhalant canals in a sandwich culture of the demosponge Halichondria panicea in contact with the ‘mother sponge’ using microscope-video technique. Algal cells traced near the centreline of an inhalant canal moved with the highest speed and travelled the furthest, and when approaching the canal walls the flow speed decreased and the cells were captured to be subsequently digested. Microplastic particles accumulated also along the inhalant canal walls but were subsequently expelled into the exhalant canals. Adding a high concentration of 2–22 µm fragmented waste plastic particles triggered contractile behaviour. It started immediately with osculum closure in the ‘mother sponge’ lasting about 25 min and it was followed by delayed and temporary contractions of first inhalant and then exhalant canals in the sandwich culture. These results support the theory of how the sponge responds to ultimately ensure the ejection of the foul particles.

Numerical study of downwash flow on rice plant protection drone with computational fluid dynamics method

Unnamed Unmanned Aerial Vehicles (UAVs) are increasingly being utilized in various industries, including agriculture, to support the growing demand for food. UAVs streamline work processes and are particularly useful in the spraying method for plant protection. This study aims to analyze the characteristics of the downwash flow, which are influenced by factors such as flight altitude, airfoil profile, and the flying speed of the drone. Unlike previous studies that used 6-blade UAVs, this research focused on a 4-blade configuration. The study employed Computational Fluid Dynamics (CFD) to analyze drone geometry and input boundary conditions based on environmental factors. The drone's flying altitude significantly impacted downwash flow, particularly concerning In Ground Effect (IGE) and Out of Ground Effect (OGE) conditions. Unlike previous research, this study considered the airfoil profile of the propeller, which, along with the drag and lift coefficients from the airfoil geometry, affected the downwash flow. The drone's flying speed, related to the relative wind speed around its working area, also influenced pressure distribution and downwash flow speed. These factors significantly impacted downwash flow and determined the distribution of plant protection droplets on the rice field. The results indicated that increasing flight altitude reduced the ground effect, affecting the quadcopter's downwash. Similarly, flight speed had a similar effect on downwash as altitude. Based on these findings, the study recommended a flight altitude of 2 m and a speed of 2 m/s for optimal downwash and proper distribution of plant protection.

Behavioral characteristics of bidirectional pedestrian-e-bike mixed flow at a signalized crosswalk: An experimental study

Mixed-traffic crosswalks are a prevalent scene in urban traffic. Understanding the movement characteristics of bidirectional e-bike-pedestrian mixed flow is helpful to enhance traffic efficiency at an intersection. In this research, a controlled experiment on bidirectional e-bike-pedestrian mixed flow was conducted. There are three variables, namely the proportion of e-bike riders (i.e., 0.5 and 0.3), the directional split ratio (namely, 1:1, 1:2 and 1:5) and the presence of obstacles on both sides of the crosswalk (i.e., yes and no). Petrack software were used to extract the participants’ trajectories. Passing time, detour ratio, selection preference, fundamental diagrams, the temporal and spatial characteristics and congestion level are analysed depending on the trajectories. It is discovered that a higher proportion of e-bike riders combined with a smaller directional split ratio contributes to increasing passing time of e-bike riders. With the decreasing directional split ratio, the average detour ratios of both pedestrians and e-bike riders decrease. With the decreasing proportion of e-bike riders, the average detour ratio of pedestrians increases, while that of e-bike riders decreases. The average crossing speed of the minor flow is greater than that of the major flow. With the decrease of the directional split ratio, the congestion level in the measurement area also reduces. Pedestrians in balanced flow are more likely to cause large congestion degree than e-bike riders. These results are beneficial for the design of crosswalks, pedestrian crossing management and the configuration of traffic signals.

An experimental study of noise generated by tandem blades

To facilitate the low-noise design of tandem lift bodies as applied in aeroengines and aircraft, the acoustic features of tandem blades are investigated by wind-tunnel experiments. This is further specialized for the rotating blades applied in contra-rotating open rotors under the concept of frozen-rotor. A 70-channel phased microphone array and nine high-precision free-field microphones are employed. The beamforming method, enhanced by a source filtering technique, is employed to locate noise sources, providing insights into the source patterns of blade-blade interaction noise concerning flow speed, blade spacing, and aft blade clipping. The results show the following: (A) Sources of tandem-blade noise exist in the form of concentrated source clusters, resulting in two major clusters: the mid-span interaction noise and the tip-induced noise. (B) These source clusters tend to separate as flow speed or blade spacing increases. (C) By increasing blade spacing, the band-pass filtered overall sound pressure level is reduced by 2.9 dB. (D) A two-phase noise suppression pattern is observed with blade clipping, resulting in a total reduction of 3.0 dB for the interaction noise through the removal of tip-induced noise sources and the replacement of mid-span noise sources. Based on these findings, suggestions concerning blade spacing and clipping are discussed.

GSM Based Canal Gate and Flood Monitoring and Control System

Technology based modern Irrigation systems are the recent requirement in every part of world today. The irrigation water is being used for agricultural, industrial and domestic purposes. Owing to mismanagement and inequitable distribution of water, it is necessary to have a fool-proof system where water is supplied to the end-users judiciously. Due to the variable atmospheric circumstances these conditions sometimes may vary from place to place, which makes very difficult to operate the canal gate manually and instantly. Therefore, we proposed. The “GSM based Canal gate and Flood monitoring and control system’’ canal gates are monitored and controlled after sensing the water level and flow speed. In our project the water level and flow will be calculated automatically and send towards the operator through SMS and the Canal Gate is operated according to the collected data, this system also Announce flood in case of high level of water and speed of water in River or canals by the help of Alarming as well as lightning tower with green, yellow and red lights indication of normal, intermediate and flood conditions respectively.

400. MODIFICATION OF THE LESSER CURVATURE INCISION ENHANCES GASTRIC CONDUIT BLOOD FLOW AND DECREASE ANASTOMOTIC LEAKAGE RISK AFTER ESOPHAGECTOMY

Abstract Background We conducted this study to investigate the effectiveness of a modified incision line on the lesser curvature for gastric conduit formation during esophagectomy in enhancing the perfusion of the gastric conduit, as determined by indocyanine green (ICG) fluorescence imaging, and reducing the incidence of anastomotic leakage. Methods A total of 272 patients who underwent esophagectomy at our institution between June 2014 and August 2022 were enrolled in the study. The patients were divided into two groups in accordance with the type of cutline on the lesser curvature: the Conventional group, consisting of patients operated on until 2018 (Conventional group; n = 141), in which the traditional cutline (5.0 cm from the pylorus in routine) was adopted, and the Current group, consisting of patients operated on from 2019 until date (Current group; n = 131), in which a modified cutline on the lesser curvature was adopted, that allowed preservation of the entire right gastric artery was adopted (hereinafter, modified cutline) was adopted. Gastric conduit perfusion during the surgery was assessed by intraoperative ICG fluorescence imaging, and the clinical outcomes after esophagectomy were also evaluated. Results All patients underwent esophagectomy with regional lymph node dissection and gastric conduit reconstruction via the retrosternal route. The distance from the pylorus to the cutline was significantly longer in the Current group as compared with the Conv group (median: 9.0 cm vs. 5.0 cm, p < 0.001). The blood flow speed in the gastric conduit wall assessed by ICG fluorescence imaging was significantly higher in the Current group than that in the Conventional group (median: 2.81 cm/sec vs. 2.54 cm/sec, p = 0.001). Furthermore, the incidence of anastomotic leakage was significantly lower (p = 0.024) and the hospital stay significantly shorter (p < 0.001) in the Current group as compared with the Conventional group. Logistic regression analysis using the data of the entire cohort identified the blood flow velocity in the gastric conduit wall as the only variable that was significantly (negatively) associated with anastomotic leakage. Conclusions ICG fluorescence imaging is a feasible, reliable method for intraoperative assessment of gastric conduit perfusion. Use of the modified lesser curvature cutline could enhance gastric conduit perfusion, promote blood circulation around the anastomosis and ultimately reduce the risk of anastomotic leakage after esophagectomy.

Auroral Bead Propagation: Explanation Based on the Conservation of Vorticity

AbstractThe beading of auroral arcs often takes place at substorm onset. It is known that auroral beads propagate more often eastward than westward at several km/s, which is difficult to explain by existing models. We investigate this issue observationally and theoretically. First, based on previous research and additional statistical analysis, we suggest that (a) auroral beads often propagate eastward in the presence of westward background convection, and (b) background ionospheric convection may be better represented by large‐scale convection for westward propagation, and by meso‐scale convection for eastward propagation. Then we model auroral beads as vortices of ionospheric flow, and consider the longitudinal propagation of their meridional displacement based on the conservation of vorticity. Here it is crucial that the background zonal flow has vorticity (i.e., flow shear) changing with latitude. It is found that the wave propagates either parallel or anti‐parallel to the background flow depending on whether the background vorticity increases or decreases in latitude, and if its latitudinal scale is significantly smaller than the longitudinal wavelength, the phase velocity exceeds the background flow speed. The result suggests that the latitudinal structure of the background flow is crucial for the bead propagation. More specifically, the aforementioned feature (a) implies that the zonal flow associated with eastward propagation is confined in latitude, which may correspond to the preonset approach of mesoscale flows. In contrast, the large‐scale ionospheric flow suggested for westward propagation as described in (b) may correspond to the global convection of the conventional growth phase.

Advancing Blood Flow in Stenotic Arteries through Magnetohydrodynamic Peristaltic Motion of Hybrid Nanoparticles

This research aims to investigate the efficacy of hybrid nanoparticles in improving magnetohydrodynamic (MHD) peristaltic blood flow in stenotic arteries. Hybrid nanoparticles combining MHD processes and peristaltic motion show promise for increasing blood flow through constricted arteries. To evaluate the impact of nanoparticles on blood flow parameters, researchers use theoretical modelling and analytical solutions. Incorporating copper and aluminium oxide nanoparticles (Cu-Al2O3) into blood, leading to the formation of an ionic solution, is a crucial step in creating a homogeneous hybrid blood suspension. The mathematical model uses approximations of the stenosis and non-dimensional parameters for a mild stenosis scenario to simplify the underlying coupled nonlinear partial differential equations. Analytical solutions for various blood flow parameters such as velocity, temperature, stream function, wall shear stress, Nusselt number, and flow resistance impedance are obtained using the perturbation technique. This study visually analyzes how different physiological variables affect arterial blood flow characteristics. The heat conductivity of blood is an essential aspect of preserving one's sustenance, which is largely determined by the concentration of hybrid nanoparticles. A streamlined pattern depicts the direction of blood flow within an artery. This research demonstrates that the adverse effects of vascular stenosis can be mitigated by using hybrid nanoparticles. In order to aid narrowed arteries, these nanoparticles lessen wall shear stress, boost axial flow speed, and enhance the velocity profile.

Numerical model of changes in current patterns due to reclamation around the Mireng River estuary, Gresik

Abstract The Mireng River is in Gresik Regency and empties into the Madura Strait. Around the mouth of the Mireng River, two industrial areas require construction facilities through reclamation. The consequences of reclamation will cause phenomena due to the interaction of marine and environmental dynamics, which can change current patterns, wave heights, and sedimentation processes, affecting the surrounding environment. This study explicitly discusses the changes in flow patterns that occur due to reclamation. The investigation was performed using numerical model simulations with Delft 3D software. The model results show the movement pattern and current speed during the highest and lowest low tides. There was a change in the average flow speed to 0.18 m/s around the reclamation area due to flow obstruction due to reclamation. This condition has the potential for sedimentation to occur in the area. Therefore, mitigation efforts are needed to reduce this impact.

Isogeometric modeling and vibro-acoustic analysis of flow-excited irregular cavity-plate-exterior space coupled system

The flow-induced noise has become an important noise source in marine sonar self-noise, which can adversely affect the normal operation of sonar. The marine sonar cabin is simplified as a cavity-plate-exterior space coupled system whose flow-induced vibro-acoustic characteristics are investigated in this paper. An isogeometric vibro-acoustic formulation is proposed in which the cavity with an irregular geometry is precisely described by adjusting the control points and corresponding weights. The flow-induced vibro-acoustic response is obtained by transferring the turbulent pressure data from computational fluid dynamics into the isogeometric vibro-acoustic model. Imposing turbulent pressure into the isogeometric control points is proposed to achieve this objective using a node-based interpolation method. The vibro-acoustic modeling is validated and compared with previous experimental results. These comparisons demonstrate that the developed formulation accurately predicts the vibro-acoustic characteristics of the fluid-excited coupled system. The influences of flow speed, acoustic medium, and cavity shape on flow-excited vibration and sound radiation are discussed. Results show a decrease in radiated acoustic power and radiation efficiency in the exterior space, and a shift in the plate-exterior space coupling modal frequency to lower frequencies when the cavity changes from convex to concave.

Numerical investigation on the ventilated supercavitating model with propeller

To achieve stable and continuous supercavitating flow over underwater vehicles, artificial ventilation is implemented, particularly effective at lower speeds. Previous research on supercavitation primarily focused on analyzing ventilated supercavitating flow with various cavitator types and/or ventilation rates. In this investigation, we examine the behavior of ventilated supercavitating flow over an axisymmetric model featuring both a disk cavitator and a Postdam propeller placed at the bow. Utilizing the Large Eddy Simulation turbulence model, Volume of Fluid method, and Kunz cavitation model, our simulation aims to capture the cavitating flow around the propeller and the ventilated supercavitating flow over the model. Validation of our numerical methods is achieved by comparing our results with experimental data of a ventilated model by Chung and Cho [“Ventilated supercavitation around a moving body in a still fluid: Observation and drag measurement,” J. Fluid Mech. 854, 367–419 (2018)] and the cavitating Postdam propeller by SVA Postdam [S. Potsdam, “PPTC smp'11 Workshop,” in Proceedings of the Workshop on Cavitation and Propeller Performance (2011)]. The results show that with a rotating propeller at the bow of the supercavitating model, the cavitating flow extends and stabilizes compared to configurations utilizing a traditional disk cavitator. The presence of the propeller accelerates the formation of supercavitating flow at a consistent incoming flow speed. Additionally, coupling the propeller with the disk cavitator results in significant increases in propeller thrust, torque, and efficiency. While there is an observed rise in model drag, the impact is not substantial.

RESULTS OF EXPERIMENTAL STUDIES ON THE IMPROVED SEED DELIVERY SYSTEM OF A PNEUMATIC PRECISION SEEDER

The research is dedicated to improving the structural and technological parameters of pneumatic seeders, particularly the seed delivery system in John Deere 90 series seeders. It has been identified that existing designs have shortcomings, especially when using No-till, Strip-till, and Mini-till technologies, leading to uneven seeding and reduced yields. To enhance the efficiency of the crop seeding process, it is necessary to refine the design of the elements within the seed delivery system of the pneumatic seeder, including the seed decelerator, seed channel of the seeder shoe, and seed stabilizer, by employing well-founded structural and technological parameters that ensure precise seeding and by using materials that increase their durability. The goal of the research was to optimize the structural parameters of the seed delivery system by developing and testing a new seed decelerator. Experimental studies were conducted using a laboratory setup that allows for variation in parameters such as air flow speed, seeder movement speed, seed injection speed, and the ratio of outlet areas to the inlet area of the seed decelerator. As a result of the experimental studies, patterns of changes in air flow speed at the seeder shoe outlet, seed flow speed of rapeseed and peas, seeding rate, and accuracy (coefficient of variation) were established depending on the ratio of outlet areas to the inlet area of the seed decelerator, air flow speed at the inlet, seeder movement speed, and seed injection (dosing) speed. The results showed that increasing the air flow speed at the inlet leads to an increase in the flow speed at the outlet, which affects the seeding rate and accuracy. The seeder movement speed and seed injection speed significantly influence the seeding rate but may reduce accuracy. A relationship was established between the number of holes in the seed decelerator (ε), seeder movement speed, and seeding rate, allowing for maximum seeding accuracy. The obtained equations will be used for the automated control system of the seed decelerator damper.

Evaluation of an experimental prototype in an aerodynamic tunnel with characteristics of a small wind turbine with two blades

The experimental consideration of wind turbines in an aerodynamic tunnel is a powerful alternative to determine the performance of these equipment, both to assimilate their behavior in operation, and to identify constructive and aerodynamic aspects, aiming to convert these characteristics to the real turbine. In the understanding described in this work, the aerodynamic characteristics of the prototype were evaluated, the static torque for the different flow speeds and the power coefficient was estimated based on the concept of variation in the amplitude of movement of the drying when crossing the turbine at different speeds of the flow. The results are compared with the values achieved analytically. The research theory predicted the aerodynamic and structural event, investing numerical and experimental tools. The present work constituted the first experimental event to evaluate the aerodynamic performance of the research project. At this stage, the experimental assessment of static torque was carried out, analyzing the aerodynamic wake of the prototype and determining the RPM curves for the attached wind speeds. The perspective is that it will be possible to describe a new process to, based on the correlation coefficients, determine a curve of the amount of energy granted by a source in a reliable unit of time through simulation or prototyping before starting the survey of real module equipment.

Application of Abrasive Water Jet Cutting on Rubber Wood Plastic Composites

Wood-plastic composites (WPCs) possess a diverse arrange of advantageous characteristics resulting from the combination of wood and plastic. These include a prolonged lifespan, cost-effectiveness, and environmental friendliness. However, the net shape can only be roughly achieved by the extrusion method used to make WPCs. WPCs require additional machining to comply with the dimensional accuracy and assembly conditions. As a result, more research into the cutting process of this composite is needed. In this work, abrasive water jet cutting was used to cut WPCs manufactured from rubber wood flour and polypropylene (PP). The emphasis was on two distinctive architectures of 1-layered and 3-layered WPCs with a thickness of 10 mm. The effects of cutting factors including water pressure, traverse speed, and abrasive mass flow rate were taken into account. The study employed a full factorial analysis to investigate the correlation between cutting parameters and cutting performance, including kerf characteristics and machined surface roughness. The abrasive and water pressure in the experiment had a significant effect in cutting both materials. In some cutting conditions, without an abrasive, non-through cutting happens, particular for the 3-layered WPC structures, that are particularly strong. An increase in water pressure decreased machining surface roughness and kerf width. The cutting parameters of 350 MPa water pressure, 30 mm/s traverse speed, and 6.67 g/s abrasive flow rate were suggested for both the 1-layered and 3-layered WPCs structures. This procedure was considered suitable for post-cutting without requiring for surface finishing.

Synthesis of NO by rotating sliding arc discharge reactor with conical-spiral electrodes

The present work investigates the potential applications of nitrogen oxides (NO x ), particularly nitric oxide (NO) and nitrogen dioxide (NO2), generated through discharge plasma in diverse sectors such as medicine, nitrogen fixation, energy, and environmental protection. In this study, a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO x , followed by the utilization of a molybdenum wire redox reactor for NO2-to-NO conversion. The outcomes reveal that the discharge states and generations of NO x are affected by varying parameters, including the applied energies, frequencies and airflow states (1.3–2.6 m/s are the laminar flow, 2.6–5.2 m/s are the transition state, 5.2–6.5 m/s are the turbulent flow), and the concentrations of NO x within the arc discharge are higher than that in the spark discharge. Moreover, the concentrations of NO, NO2 and NO x gradually increased, and the concentration ratios of NO/NO2 and NO x /NO2 decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ. Meanwhile, the concentrations of NO, NO2 and NO x gradually decreased, and the concentration ratios of NO/NO2 and NO x /NO2 first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz. Further, the concentrations of NO, NO2 and NO x gradually decreased, and the concentration ratios of NO/NO2 and NO x /NO2 first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s. Lastly, the concentrations of NO increased and NO2 decreased with increasing temperature from 25 °C to 400 °C using molybdenum converted. These findings provide experimental support for the application of plasma in the fields of medicine, nitrogen fixation, energy and environmental protection.

Synchronous PIV measurements of a self-powered blood turbine and pump couple for right ventricle support

A blood turbine-pump system (iATVA), resembling a turbocharger was proposed as a mechanical right-heart assist device without external drive power. In this study, the iATVA system is investigated with particular emphasis on the blood turbine flow dynamics. A time-resolved 2D particle image velocimetry (PIV) set-up equipped with a beam splitter and two high speed cameras, allowed simultaneous recordings from both the turbine and pump impellers at 7 different phased-locked instances. The iATVA prototype is 3D printed using an optically clear resin following our earlier PIV protocols. Results showed that magnetically coupled impellers operated synchronously. As the turbine flow rate increased from 1.6 to 2.4 LPM, the rotational speed and relative inlet flow angle increase from 630 to 900 rpm, and 38 to 55% respectively. At the trailing edges, backflow region spanned 3/5 of the total passage outlet flow, and an extra leakage flow was observed at the leading edge. For this early turbine design, approximately, 75% of the turbine blade passage was not contributing to the impulse operation mode. The maximum non-wall shear rate was ~ 2288 s−1 near to the inlet exit, which is significantly lower than the commercial blood pumps, encouraging further research and blood experiments of this novel concept. Experimental results will improve the hydrodynamic design of the turbine impeller and volute regions and will be useful in computational fluid dynamics validation studies of similar passive devices.

Numerical approach for the simulation of flow-induced noise around a structure with complex geometry: High-speed train bogie in a cavity

The bogie region is a significant source of aerodynamic noise on high-speed trains. Owing to its complex geometry and flow field, numerical simulations using computational fluid dynamics are especially challenging. The main challenge is to achieve a grid with adequate resolution, especially in the boundary layer, while ensuring computational affordability. This challenge is addressed here by employing a hybrid grid, integrating a structured hexahedral mesh near solid surfaces with an unstructured polyhedral mesh in the remaining volume. To limit the number of cells in the boundary layer region, the delayed detached eddy simulation method is adopted. Additionally, to achieve a further reduction in the cell count, the Reynolds number of the model is decreased by scaling down the model size and lowering the inflow speed. The hybrid grid generation and numerical settings are guided by validated simulations of flow over cylinders. A grid sensitivity study, conducted with a simplified half-width bogie model, reveals the meshing requirements for the full-width model. Aerodynamic results highlight the rear section of the cavity and bogie as primary noise sources, emphasizing the critical role of the detached shear layer from upstream components. Time-resolved surface pressure data are input into the Ffowcs Williams–Hawkings equation for far-field noise calculation. The results indicate that the sound energy is concentrated below 200 Hz in the full-scale model, with the cavity contributing more than the bogie. This study provides a practical numerical approach for simulating a structure with complex geometry, offering insights for realistic model simulations.

Evaluation of hydrodynamic coefficients and sensitivity analysis of a work-class remotely operated vehicle using planar motion mechanism tests

This paper presents a comprehensive analysis of the hydrodynamic forces and moments relating to the drag on an open-frame work-class remotely operated vehicle (ROV) AUTO-1000. We describe the results of planar motion mechanism experiments conducted with the aim of modeling and simplifying the mathematical maneuverability model for such an ROV. The scale of the model is 1:4. Various experiments are performed in a nonlinear wave channel. The flow speeds in the static drag tests range from ±0.2–±0.5 m/s and the angle in the drift tests is less than 10°. The motion frequencies of the dynamic tests range from 0.25 to 3.14 rad/s. The amplitude of the translation motions is 0.03 m and the largest angular amplitude in the rolling tests is 5°. The viscous and inertial hydrodynamic coefficients are estimated. Normalized sensitivity coefficients are used to investigate the sensitivity of both the viscous and inertial hydrodynamic coefficients considering the multi-degree-of-freedom motion and velocity effect. The drag, drift, and stationary random motions are used to examine the sensitivity. A comparison of the motion simulation results given by simplified and complete models shows that a threshold normalized sensitivity coefficient value of 0.01 is suitable for filtering the ROV coefficients.

Validation study of RWM stability in DIII-D high-βN plasmas

Abstract The n = 1 (n is the toroidal mode number) resistive wall mode (RWM) stability is numerically investigated for two DIII-D high-β N discharges 176440 and 172461, utilizing the MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) and MARS-K (Liu et al 2008 Phys. Plasmas 15 112503) codes. Systematic validation efforts are attempted, for the first time, for discharges with very slow or vanishing toroidal flow for a large fraction of the plasma volume. While gaining physics insights in accessing stable operation regime at β N exceeding the Troyon no-wall limit in these slow-rotation experiments, the predictive capability of fluid and non-perturbative magnetohydrodynamic-kinetic hybrid models for the RWM is further confirmed. The MARS-F fluid model, with a strong but numerically tunable viscosity mimicking ion Landau damping of parallel sound waves, finds complete stabilization of the n = 1 RWM in the considered DIII-D plasmas under the experimental flow conditions. Similarly, either full stabilization (for discharge 176440) or marginal stability (for discharge 172461) of the mode is computed by the MARS-K hybrid model, which is first-principle based without free model parameters. In particular, all drift kinetic resonances, including those of thermal and energetic particles, are found to synergistically act to marginally stabilize the RWM in discharge 172461. These MARS-F/K modeling results explain the experimentally observed stable operational regime in DIII-D, as far as the RWM stability is concerned. Extensive numerical sensitivity studies, with respect to the plasma toroidal flow speed as well as the radial location of the resistive wall, are also carried out to further support the validation study.

Development of snow-blowing structures for protection roads from snow drifts

Introduction. The article discusses the use of the snow blowing method and the possibility of installing snowblowing structures on highways to protect against snow drifts. The problem of snow tolerance is identified due to the location of many highways in remote, hard-to-reach areas and difficult climatic conditions. Snow drifts significantly increase the cost of winter maintenance of roads, are a partial consequence of destruction and maintenance in the summer, and also pose a serious threat to safety, causing loss of control over the vehicle.Research methodology. The article discusses the application of the snow blowing method and the possibility of installing snow-blowing structures on roads to protect against snow drifts. The process of movement of snow particles in a snowstorm and the influence of these processes on snow blowing are considered.Results. The paper highlights the issues related to the analysis and assessment of the speed and composition of the air flow, weather conditions affecting the operation of structures. The main purpose and working conditions of snow-blowing structures on highways have been determined. The optimum speed at which the snow blowing effect is created is determined.Conclusion. The snow blowing process on the developed snow blowing structure in different conditions is modelled. Based on the considered approach, a comparative analysis of the operation of the snow blowing structure is performed. Based on the data obtained, the possibilities for the introduction of snow-blowing structures and refinement in real working conditions have been studied.