Flow Motion Research Articles

Numerically investigation of particle distribution in industrial-scale DTB crystallizer based on CFD modelling

The suspension state of crystals in the crystallizer is one of the important indicators for evaluating the adaptability of the crystallizer. This study adopted the Euler-Eulerian two-fluid model to simulate and analyze the fluid motion of solid-liquid two-phase flow in the industrial-grade DTB crystallization kettle, as well as the phase suspension distribution of crystal particles. The main influencing factors investigated are: the heat transfer effect, the height of the bottom of the crystallizer, the number and position of the stirring paddle, crystal size and crystal volume fraction. Based on the research of Euler-Eulerian method to simulate fluids, the Euler-Lagrangian method was further used to simulate the motion state of particle phases with different particle sizes in the crystallizer. It was found that the designed DTB crystallizer has good recycle mixing effect. The particles can be mixed evenly during the operation, which can fully realize the solid-liquid mixing and suspension effect of the drug under study.

An efficient motion visual learning method for video action recognition

Currently, efficient spatio-temporal information modeling is one of the key research components to solve the action recognition problem. Previous approaches focus on enhancing the backbone features individually using hierarchical structures, and unfortunately, most of them fail to achieve a better balance between the interactional adequacy of features within the structure. In this work, we propose an effective Multi-dimensional Adaptive Fusion Network (MDAF-Net), which can be embedded into the mainstream action recognition backbone in a plug-and-play manner to fully activate the transfer and representation of action features in the deep network. Specifically, our MDAF-Net contains two main components: the Adaptive Temporal Capture Module (ATCM) and the Extended Spatial and Channel Module (ESCM). The ATCM effectively suppresses the over-expression of similar features in adjacent frames and activates the expression of motion flow information. The ESCM further improves temporal modeling efficiency by extending the spatial feature perceptual field and enhancing channel attention. Extensive experiments on several challenging action recognition benchmarks, such as Something-Something V1&V2 and Kinetics-400, demonstrate that the proposed MDAF can achieve state-of-the-art and competitive performance.

Метод потоков в диагностике угроз национальной экономической безопасности России

The work identifies the problem of discrepancy between the rapidly growing importance of national economic security (NES) of Russia and the degree of its scientific elaboration according to such criteria as clarity in defining the subject of NES, methodology for studying NES, mechanisms for connecting scientific research with education and practice of NES. The article is devoted to the study of the dynamics of teacher and scientist staff. The research is carried out using a new method developed by the author – the Flow Method. The novelty of the Flow Method begins with a change in the idea of the object of study. In traditional approaches, an object is fixed, and is studied from different sides in different periods of time; the Flow Method focuses the researcher’s attention on the movement of resource flows in the economic environment. In such a movement of resources, the following are distinguished: inflows, outflows, accumulations. Normally, the movement of resources is balanced. It is appropriate to consider sanctions as the most important component of a hybrid war, aimed at unbalancing the resources of the national economy by blocking flows. The study showed that the representation of the movement of resources by the Flow Method differs from traditional representations in statistics and accounting. Approbation of the Method in diagnosing the state of personnel in scientific and educational institutions showed strategic threats to the national security of the Russian Federation. Since 2015, the number of scientists and teachers with an academic degree has been continuously decreasing. The flow method allows us to dispel the myth that if scientists leave region A, they will simply work in another region. This study refutes such a hypothesis. Scientists, in particular, can change their specialty, leave the country, etc. The noted situation is similar for all 16 cities with a population of over a million in Russia, including Moscow and St. Petersburg and 18 constituent entities of the Russian Federation. The influx of young scientists is decreasing while the workforce continues to age. If we ignore the results obtained, then in 5–10 years, for example, the Omsk region will begin to lose the ability to train specialists with higher education, not to mention candidates and doctors of science. A similar situation awaits other regions.

The Evolution of Grain Microstructure in Friction Stir Welding of Dissimilar Al/Mg Alloys with Ultrasonic Assistance.

The process of grain refinement during welding significantly influences both the final microstructure and performance of the weld joint. In the present work, merits of acoustic addition in the conventional Frictions Stir Welding (FSW) process were evaluated for joining dissimilar Al/Mg alloys. To capture the near "in situ" structure around the exit hole, an "emergency stop" followed by rapid cooling using liquid nitrogen was employed. Electron Backscatter Diffraction analysis was utilized to characterize and examine the evolution of grain microstructure within the aluminum matrix as the material flowed around the exit hole. The findings reveal that two mechanisms, continuous dynamic recrystallization (CDRX) and geometric dynamic recrystallization (GDRX), jointly or alternatively influence the grain evolution process. In conventional FSW, CDRX initially governs grain evolution, transitioning to GDRX as material deformation strain and temperature increase. Subsequently, as material deposition commences, CDRX reasserts dominance. Conversely, in acoustic addition, ultrasonic vibration accelerates GDRX, promoting its predominance by enhancing material flow and dislocation movements. Even during the material deposition, GDRX remains the dominant mechanism.

Capital Flow Management Within Macroeconomics Stability Framework in Indonesia (2008 – 2022)

Indonesia is an EMDEs (Emerging Market and Developing Economies) country, and adopting an open economy causes foreign capital flow, especially FDI (Foreign Direct Investment) and PI (Portfolio Investment) can be free flows, and its movements are unpredictable. The movement of capital flows will affect the money supply transmitted to monetary and macroeconomic variables. This study aims to determine the response and contribution of macroeconomic variables to FDI and PI, as well as examining the causality between macroeconomic variables, FDI and PI. This research used the Vector Error Correction Model Granger Causality. The results show that exchange rate and inflation shocks significantly impact FDI and PI. While the results of Granger causality, changes in macroeconomic variables cause changes in FDI and PI. This research recommends that stakeholders continue implementing policy mix and monetary policy to improve exchange rates and inflation stability. In addition, the management of capital flows is still considered because the potential risks posed to the economy are quite large

Выставочное пространство российских музеев как объект культуры

The article examines the exhibition space of Russian museums of the Soviet and post-Soviet periods as an object of culture. Emphasis is placed on its importance in shaping and reflecting social values, and the evolution of exhibition spaces, design elements, and the role they play in presenting, interpreting, and preserving cultural heritage are examined. The discussion covers the layout, interconnection and functionality of the various zones inside the museum. The tasks in designing architectural and artistic solutions for museum complexes are perhaps one of the most difficult in environmental design. Here it is necessary to take into account functionality, ergonomics, aesthetics, subordinating them to the general concept of the museum complex, considering the regularity of the location of objects, the movement of visitor flows, the zoning of space, taking into account the safety and preservation of cultural objects. The article highlights the design features of the museum space of the XX–XXI centuries, taking into account historical changes, political realities, stylistic trends and trends in art.

Flow structure and heat transfer of a two-cylinder array

Two cylinders in staggered and tandem configurations were experimentally investigated to understand how the flow structure influences heat transfer. The results indicate the heat transfer of downstream cylinder exhibits more variability than that of the upstream cylinder as the stagger angle changes. The heat transfer characteristics for each flow pattern and the mechanisms governing heat transfer for the cylindrical array were clarified. Additionally, the significant effects of flow motion on the local Nusselt number of the cylinder surfaces resulting from varying stagger angles were elucidated. The overall Nusselt number in a staggered array system increases with the stagger angle, whereas in a tandem array system, it increases with the distance ratio. Notably, staggered cylinder arrangements exhibited a more pronounced enhancement in heat transfer compared to the tandem arrangement.

An exceptional record of soft-sediment deformation within Pliocene deposits of Faro Drift (SW Iberia margin) - IODP Expedition 339 Sites U1386 and U1387

The occurrence of soft-sediment deformation structures (SSDS) have long been recognized in several types of sedimentary environments and deposits. However, their presence in contourite drift deposits is still unreported in the literature. In this work, we present the first detailed description of SSDS found within the Pliocene sedimentary record of the Faro Drift, recovered during the Integrated Ocean Drilling Program (IODP) Expedition 339. The Faro Drift is the largest contourite drift of the Contourite Drift Depositional System developed in the Gulf of Cadiz since the Late Miocene by the circulation of the Mediterranean Outflow Water. The SSDS were identified in archive-halves of core sections located between ∼458 and ∼ 510 m below seafloor (mbsf) (hole U1386C), and between ∼599 and ∼ 670 mbsf (hole U1387C). Their identification and characterization was made by visual core description, structural geometrical analysis in core-scan high-resolution images, and scanning electron microcopy (SEM) analysis in selected intervals. The SSDS were classified based on the exhibited geometry, structural configuration and respective kinematics. The main deformation process and potential trigger were inferred from the geometrical and kinematics analysis. We identified five categories of SSDS: i) microfaults (normal and thrust faults), ii) slump sheet (formed by several types of folds, such as eye-folds, fish-hook folds, spiral folds), iii) convolute bedding, iv) folds within debrite mudclasts', and v) sigmoidal-like structures. Although the first three are well known types of SSDS, the folds within debrite mudclasts' and sigmoid-like structures have been scarcely recognized and described at core-scale. The inferred deformation processes responsible for the formation of these SSDS were i) brittle deformation by hydrofracturing and compaction faulting (microfaults), ii) hydroplastic (ductile) deformation (slump folds, folds within debrite mudclasts'), iii) liquefaction (convolute bedding), iv) shearing by flow movement (sigmoid-like structures). The most probable triggering agents seem to have been overloading, downslope movement of slump sheet and debris flow, and shearing by currents.

Diversity of solitonic wave structures to the M‐truncated dynamical system in ultrasound imaging

The utilization of ultrasound imaging has become extensively prevalent and well‐established in clinical practice. The fundamental technologies that serve as the foundation for various applications in the field include transducers, beam shaping, pulse compression, tissue harmonic imaging, contrast agents, methodologies for quantifying blood flow and tissue motion, and three‐dimensional imaging. This article focuses on the examination of ultrasonic propagation, which involves the transmission of mechanical vibrations within the molecules or particles of a material. It quantifies the velocity of sound propagation in the medium of air. The third‐order nonlinear M‐fractional Westervelt model has been used as a governing model in the imaging process for securing the different wave structures. The recently developed computational methods have been applied in this study. The different wave structures are secured in various forms of solitary wave solutions including bright, dark, and combo solitons. In the domains of medical imaging and therapy, the investigation of sound wave propagation and high‐amplitude phenomena is facilitated by the utilization of wave structures. The effectiveness of these solutions extends to acoustic cavitation, acoustic levitation, underwater acoustics, and facilitating the process of ultrasonic propagation in tissue. Ultrasound imaging technologies currently find application in the medical field, enabling the visualization and examination of internal human tissue. This technology exhibits a wide array of applications in the fields of industry and medicine. A representation of the graphs is produced using the appropriate parametric values. The results suggest that the chosen approaches exhibit effectiveness, viability, and adaptability when implemented in complex systems in various fields, with particular emphasis on ultrasonic imaging.

Control on Flow Separation over a Cylinder by a Ferrofluid Film Adsorbed by a Magnet

Flow separation can lead to increased resistance and vibration generation, which is a difficult problem that cannot be ignored in engineering. In this paper, we propose a method of controlling flow separation by adsorbing ferrofluid onto the surface of a magnetized cylinder, taking the common flow around a cylinder as an example. Parametric effects of the ferrofluid film, including its viscosity and thickness, on the flow behavior were investigated in terms of the vortex shedding process, velocity distribution, dominant frequency, pressure distribution, and the flow motion inside the ferrofluid film. The results indicate that the ferrofluid film can suppress the generation of flow separation and achieve effective control, which is mainly caused by wall slip and the internal movement of the ferrofluid film. Furthermore, the flow separation control effect of ferrofluid thin films with different parameters varies, with low-viscosity ferrofluid exhibiting a superior control effect.

Rainfall-Triggered Landslides and Numerical Modeling of Subsequent Debris Flows at Kalli Village of Suntar Formation in the Lesser Himalayas in Nepal

Hazardous debris flows are common in the tectonically active young Himalayas. The present study is focused on the recurrent, almost seasonal, landslides and debris flows initiated from Kalli village in Achham District of Nepal, located in the Lesser Himalayas. Such geological hazards pose a significant threat to the neighboring communities. The field survey reveals vulnerable engineering geological conditions and adverse environmental factors in the study area. It is found that a typical complete debris transport process may consist of two stages depending on the rainfall intensity. In the first stage, debris flows mobilized from a landslide have low mobility and their runout distance is quite modest; in the second stage, with an increase in water content they are able to travel a longer distance. Numerical simulations based on a multi-phase flow model are conducted to analyze the characteristics of the debris flows in motion, including the debris deposition profiles and runout distances in both stages. Overall, the numerical results are reasonably consistent with relevant field observations. Future debris flows may likely occur again in this area due to the presence of large soil blocks separated by tension cracks, rampant in the field; numerical simulations predict that these potential debris flows may exhibit similar characteristics to past events.

Simulating dynamics of ellipsoidal particles using lattice Boltzmann method.

Anisotropic particles are often encountered in different fields of soft matter and complex fluids. In this work, we present an implementation of the coupled hydrodynamics of solid ellipsoidal particles and the surrounding fluid using the lattice Boltzmann method. A standard link-based mechanism is used to implement the solid-fluid boundary conditions. We develop an implicit method to update the position and orientation of the ellipsoid. This exploits the relations between the quaternion which describes the ellipsoid's orientation and the ellipsoid's angular velocity to obtain a stable and robust dynamic update. The proposed algorithm is validated by looking at four scenarios: (i) the steady translational velocity of a spheroid subject to an external force in different orientations, (ii) the drift of an inclined spheroid subject to an imposed force, (iii) three-dimensional rotational motions in a simple shear flow (Jeffrey's orbits), and (iv) developed fluid flows and self-propulsion exhibited by a spheroidal microswimmer. In all cases the comparison of numerical results shows good agreement with known analytical solutions, irrespective of the choice of the fluid properties, geometrical parameters, and lattice Boltzmann model, thus demonstrating the robustness of the proposed algorithm.

Research on the multiphase flow interference and motion characteristics of vehicles during an underwater salvo

A cavitation flow can greatly impact a vehicle's attitude and stability when leaving water. This paper adopts an improved delayed detached eddy turbulence model and Schnerr–Sauer cavitation model as well as the volume-of-fluid method and an overlapping grid technique to investigate this effect. The simulation method used for the cavitation model is validated. The interference effects of a transient multiphase flow, collapse loads, and the motion instability of vehicles during an underwater salvo are studied. The results show multiple obvious pressure peaks during the process of cavity collapse, which do not overlap significantly. Instead, they are sequentially arranged from the top to the end of the bubble, and the synchronous collapse pressure peak is much stronger than the other pressure peaks. The synchronous collapse pressure has a high peak and a short pulse width, and its action position is at the bottom of the shoulder cavity. The salvo time interval is zero, the launch depth is equal to the length of the vehicle, the initial cavitation number is 0.233, and the lateral launch spacing is varied from 2 times the diameter to 5 times the diameter. When the lateral spacing is in the range of 4 times the diameter to 5 times the diameter, the effect of flow interference on the underwater travel and water exit stages disappears.

Numerical investigation of sequential water entry for two projectiles at varied entry angles

In this paper, the effect of the water entry angle on the sequential water entry process of two projectiles was investigated numerically. A numerical method is established based on the STAR-CCM+ fluid simulation software, which employs the finite volume method, the volume of fluid multiphase flow model, and overlapping grid technology. The validity of the numerical method was confirmed by comparing the simulation results with experimental data. The sequential water entry processes are simulated at angles of 90°, 75°, 60°, 45°, and 30°, respectively. The flow field characteristics, motion stability, and drag reduction of both projectiles are analyzed. The results show that projectile 1 generates a series of air bubbles shedding from its cavity's tail, which distorts projectile 2's cavity. This air bubble reduces the wet area at projectile 2's head, enhancing its drag reduction capability. Projectile 1's motion remains unaffected by projectile 2 under varying water entry angles, while distinct motion characteristics are observed in projectile 2 due to significant interference from projectile 1. These results provide valuable theoretical insights for further research on sequentially launched trans-media weapons.

АНАЛИЗ ТЕХНИЧЕСКИХ РЕШЕНИЙ ДЛЯ ПОВЫШЕНИЯ ЭФФЕКТИВНОСТИ РАБОТЫ ВОДОГРЕЙНЫХ КОТЛОВ ДЛЯ СЖИГАНИЯ ОТХОДОВ В НЕПОДВИЖНОМ СЛОЕ И ВЫБОР КОНСТРУКЦИИ ГАЗОХОДА ДЛЯ РАЗРУШЕНИЯ ВРЕДНЫХ ВЕЩЕСТВ В ПРОДУКТАХ СГОРАНИЯ

The purpose of the work is to analyze technical solutions used to improve the efficiency of hot water boilers for waste combustion. As a result of the analysis of available design solutions for low-power water heating boilers, in which waste is burned in a fixed bed, their main disadvantages were identified: low combustion temperature; ineffective heat transfer from combustion products to the coolant; contamination of flues and heating surfaces; incomplete combustion of fuel; the impossibility of accurately regulating the combustion process, which leads to the formation of a large amount of harmful emissions and a decrease in the heat output and efficiency of the boiler. It is proposed to install a flue after firing the boiler, in which the gases will remain for more than 2 seconds and the organic harmful substances contained in the combustion products will be completely destroyed. To determine the passage time and select the optimal design of the gas duct, a numerical simulation of the movement of the gas flow was carried out using the developed numerical model implemented in the ANSYS Fluent software package. To ensure uniformity of the gas flow in the gas duct, options with different heights of the window between the firebox and the gas duct and the installation of a dividing partition in the gas duct to organize two-pass gas movement were considered. The best results were obtained for a horizontal flue. For further design development and search for ways to increase the residence time of gas in the gas duct, the most effective option with a horizontal gas duct was chosen.

A New Approach to the Assessment of Erectile Dysfunction Based on Vasomotion Monitored by the Flow-Mediated Skin Fluorescence (FMSF) Technique-A Preliminary Study.

Background: Erectile dysfunction (ED) most often has vascular etiology and usually is the earliest symptom of vascular dysfunction. The aim of this study was to evaluate vascular dysfunction with the use of the Flow-Mediated Skin Fluorescence (FMSF) technique in men with and without ED. Methods: Included were 39 men (median age 53) with ED and 40 men (median age 41.5) without ED. Medical interview, physical examination, and anthropometrical measurements were performed for all participants. The serum total testosterone, LH, and SHBG determinations were performed in patients with ED, and the Free Testosterone Index (FTI) was calculated. The FMSF technique was used to measure the microcirculatory oscillations at the baseline and to determine the flowmotion (FM) and vasomotion (VM) parameters. The Normoxia Oscillatory Index (NOI) was calculated, which represents the contribution of the endothelial (ENDO) and neurogenic (NEURO) oscillations relative to all oscillations detected at low-frequency intervals (<0.15 Hz): NOI = (ENDO + NEURO)/(ENDO + NEURO + VM). Results: In men with ED were found significantly lower FM and VM parameters, but the NOI was significantly higher in comparison to men without ED. VM and FM correlated significantly positively with erectile function, orgasmic function, and general sexual satisfaction in the whole group and the FTI in the ED group. The thresholds of 53.5 FM (AUC = 0.7) and 8.4 VM (AUC = 0.7) were predictive values for discriminating men with ED. Conclusions: It was shown that the FMSF diagnostic technique may be helpful in the early diagnosis of microcirculation dysfunction due to impaired vasomotion caused by decreased testosterone activity.

Modeling cerebrospinal fluid dynamics across the entire intracranial space through integration of four-dimensional flow and intravoxel incoherent motion magnetic resonance imaging

BackgroundBidirectional reciprocal motion of cerebrospinal fluid (CSF) was quantified using four-dimensional (4D) flow magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) MRI. To estimate various CSF motions in the entire intracranial region, we attempted to integrate the flow parameters calculated using the two MRI sequences. To elucidate how CSF dynamics deteriorate in Hakim’s disease, an age-dependent chronic hydrocephalus, flow parameters were estimated from the two MRI sequences to assess CSF motion in the entire intracranial region.MethodsThis study included 127 healthy volunteers aged ≥ 20 years and 44 patients with Hakim’s disease. On 4D flow MRI for measuring CSF motion, velocity encoding was set at 5 cm/s. For the IVIM MRI analysis, the diffusion-weighted sequence was set at six b-values (i.e., 0, 50, 100, 250, 500, and 1000 s/mm2), and the biexponential IVIM fitting method was adapted. The relationships between the fraction of incoherent perfusion (f) on IVIM MRI and 4D flow MRI parameters including velocity amplitude (VA), absolute maximum velocity, stroke volume, net flow volume, and reverse flow rate were comprehensively evaluated in seven locations in the ventricles and subarachnoid spaces. Furthermore, we developed a new parameter for fluid oscillation, the Fluid Oscillation Index (FOI), by integrating these two measurements. In addition, we investigated the relationship between the measurements and indices specific to Hakim’s disease and the FOIs in the entire intracranial space.ResultsThe VA on 4D flow MRI was significantly associated with the mean f-values on IVIM MRI. Therefore, we estimated VA that could not be directly measured on 4D flow MRI from the mean f-values on IVIM MRI in the intracranial CSF space, using the following formula; e0.2(f−85) + 0.25. To quantify fluid oscillation using one integrated parameter with weighting, FOI was calculated as VA × 10 + f × 0.02. In addition, the FOIs at the left foramen of Luschka had the strongest correlations with the Evans index (Pearson’s correlation coefficient: 0.78). The other indices related with Hakim’s disease were significantly associated with the FOIs at the cerebral aqueduct and bilateral foramina of Luschka. FOI at the cerebral aqueduct was also elevated in healthy controls aged ≥ 60 years.ConclusionsWe estimated pulsatile CSF movements in the entire intracranial CSF space in healthy individuals and patients with Hakim’s disease using FOI integrating VA from 4D flow MRI and f-values from IVIM MRI. FOI is useful for quantifying the CSF oscillation.

Applying SPH-DEM theory to the motion of particulate solid-liquid flow on continuous screening

Challenges in current research on fine mesh wet screening (≥50 mesh) include representing fine wire boundaries, contentious porous media handling, and low computational efficiency. To address these challenges, this study employs an averaged SPH-DEM method for modeling solid-liquid flow on screen. It integrates the Symplectic scheme and quaternion method to enhance computational accuracy and scalability. The fine wire boundaries are discretized into spheres to facilitate Hertz contact of DEM particles, and a novel screen aperture-fluid resistance model is introduced to calculate the resistance exerted on SPH particles by screen surface. The simulation results of dam break and periodic screening exhibit robust consistency with experimental data and other models, effectively validating the feasibility and accuracy of this methodology. Moreover, simulations of continuous screening using a 0.2 mm wire demonstrate that liquid enhances particle passage, further substantiating the practical viability of employing this model for simulating fine mesh wet screening.

Secondary motions in turbulent ribbed channel flows

Secondary motions in turbulent ribbed channel flows

Numerical Study on Nanoparticles Aggregation with Brownian Motion in Fluid Flow Induced by Squeezing Porous Slider

Numerical Study on Nanoparticles Aggregation with Brownian Motion in Fluid Flow Induced by Squeezing Porous Slider