Principles Of Fluid Mechanics Research Articles

Influence mechanism of AC electric field on rime ice accretion on the insulator and its experimental verification in the natural environment

Influence mechanism of AC electric field on rime ice accretion on the insulator and its experimental verification in the natural environment

Numerical Study of the Three‐Dimensional Interfacial Instability of MHD Between Parallel Plates

ABSTRACTThe stability of interfacial flows between electrically conducting fluids is a critical factor in various industrial and natural processes, such as metallurgical casting, magnetohydrodynamic power systems, and geophysical fluid dynamics. This study aims to investigate the linear interfacial stability of two conducting fluids confined between solid planes, focusing on the effects of an applied magnetic field on the lower plate. It seeks to understand how parameters like the Hartmann number, oblique angle, load parameter, and electrical conductivity influence flow stability and velocity profiles. The governing partial differential equations for the flow are derived using fluid mechanics principles and appropriate boundary conditions. Linear stability analysis is employed to analyze the system, leading to the Orr–Sommerfeld equations. These equations are solved numerically using the Chebyshev collocation method in MATLAB to explore the magnetic field's influence.

Model Studies of Metallurgical Processes Based on the Example of Blowing Steel with Argon

The task facing steel producers, which is to limit the negative impact of their production on the environment, necessitates changing the technologies used so far. These changes often require knowledge of the mechanisms of physical phenomena, mainly hydromechanical ones, occurring in steel reactors. Identification of these mechanisms in industrial conditions is difficult and often impossible for fundamental reasons. A frequently used research tool in such cases are water physical models of metallurgical reactors used in steel production. Such models are built in accordance with the principles of similarity and fluid mechanics. The article presents an overview of achievements in the field of physical modelling of steelmaking processes (including blowing liquid steel with inert gases), mathematical principles constituting the basis for the construction of steelmaking reactor models and the latest trends in their application. As an example, the results of model tests on the possibility of using a new solution in the construction of a slot-type gas-permeable module (KS diffuser) in the process of blowing liquid steel with inert gases in a steel ladle are presented. The tested process is aimed at preparing liquid steel for casting and largely determines the quality of the semi-finished product, which is a steel ingot.

Development of a mathematical model for the cooling channel of a liquid propellant rocket engine’s chamber with respect for variations in coolant density

This study focuses on the processes occurring within the cooling channels of a liquid rocket engine chamber. It is important to note that, from a design-stage efficiency prediction perspective, the cooling system is the most critical part of the engine chamber. This is because it cannot be tested without costly and labor-intensive fire tests. Therefore, mathematical models of heat transfer and fluid dynamics must describe accurately all processes taking place in the chamber. The study emphasizes accounting for the change in the density of the propellant component within the cooling channels. To verify the importance of this issue, an analysis was conducted on the changing parameters of the propellant components in the cooling channels of an engine. The assessment revealed that even when using high-boiling propellant components and moderate heating in the cooling channels, density changes can exceed 25 %. This paper presents the results of developing a model for the flow of propellant in the cooling channels of a liquid rocket engine chamber, taking density changes into account. The model builds on a cooling channel model previously developed by the authors. An equation that accounts for density variations was derived using established principles of fluid mechanics. Using the developed mathematical model, test calculations were performed, and the simulation results were compared with and without considering density changes. Furthermore, a comparison was conducted with calculated data available in the literature on heat transfer in the RD107 engine chamber, revealing an error margin of no more than 1.5 %. The resulting mathematical model may be recommended for use in the design of new rocket engine chambers with regenerative cooling

Development and characterization of a magnetorheological damper with low-velocity sensitivity

Magnetorheological (MR) dampers, utilizing the unique properties of advanced materials, are extensively applied in vibration control systems. However, their performance is often compromised by the structural limitations of conventional designs. The damping force in conventional MR dampers is highly sensitive to velocity variations, primarily due to the interdependence between the piston area and the dimensions of the throttling channels, which are typically inseparable. This inherent coupling restricts the simultaneous optimization of the damping force and adjustable damping ratio, reducing the effectiveness of the magnetorheological dampers in velocity-sensitive environments. Moreover, conventional MR dampers are often characterized by complex structures and large sizes. To overcome these limitations, a novel double-rod bypass magnetorheological damper is proposed. Through the application of fluid mechanics principles and the rheological behavior of MR fluids, the velocity distribution within the throttling channel is thoroughly examined. The Bingham model is employed to establish both the velocity profile and the corresponding mechanical model, and the theoretical results align closely with experimental data, confirming the accuracy of the quasi-static model. Experimental results further demonstrate the proposed damper’s superior sensitivity to low velocities. This approach provides valuable theoretical guidance for the design of advanced MR dampers.

Review of Potential Capabilities of 3D Printed Parts Reinforced with a Non- Newtonian Fluid for Enhancing Impact Resistance

This theoretical paper presents a comprehensive review of the promising prospects offered by the integration of non-Newtonian fluids in 3D printed parts to enhance impact resistance. Non-Newtonian fluids exhibit unique rheological behavior, and their ability to alter mechanical properties makes them an intriguing candidate for reinforcing 3D printed objects. The paper delves into the underlying principles of non-Newtonian fluid mechanics and how these fluids can be effectively utilized to augment the impact resistance of 3D printed structures. By surveying recent advancements and emerging applications, this review explores the potential benefits and challenges associated with the incorporation of non-Newtonian fluids in additive manufacturing. Furthermore, it offers valuable insights into the design, material selection, and manufacturing processes crucial for achieving robust, impact-resistant 3D printed components. This paper aims to provide a foundation for further research and development in the field, shedding light on the transformative possibilities of non-Newtonian fluid reinforcement in 3D printing.

Assessing the viability of using ground-air heat exchangers during winter months in different climatic conditions of Iran

ABSTRACT Ground combined with subsurface tubes as heat exchangers, known as Ground-Air Heat Exchangers (GAHEs), have recently gained attention for heating and cooling. However, several simplifications were used to capture complex airflow characteristics in previous studies which potentiate inaccuracy in their results. This gap is addressed in this study by developing a 3D transient model incorporating realistic heat dynamics and turbulent airflow simulation using the k-epsilon model over a complete temperature cycle. The experimental result serves to corroborate the model’s accuracy. Further, the model is utilised to assess energy-conversion potential of GAHEs for heating a generic building during January in four Iranian cities with different climates. Findings show distinct differences between the GAHE’s energy-conservation capacity in these cities. The GAHE can conserve up to 714.6 kWh of energy monthly in the coldest climate and reduce peak heating loads by up to 36.0% in the hottest climate, with these averages observed across all soil types. GAHE energy saving is increased up to 27.7% when the soil around it is silt with a higher conductivity. Additionally, an adverse impact on building’s heating is created by the GAHE in some cases, highlighting the significance of hourly management of the system. Highlights A 3D transient numerical scheme was created based on fluid mechanics principles to simulate a multitube GAHE, and the solution was verified using empirical data. The effectiveness of the GAHE and its ability to reduce the maximum heating demand of a particular building for different climates within Iran in January were examined. The impact of soil characteristics on the energy-saving capability of the GAHE was found to be significant in the four cities under study, and a distinct difference in heat flux to the working fluid was discovered in different climates.

Study on the Diffusion Characteristics of Polymer Grouting Materials Applied for Crack Filling in Underground Mines Based on Numerical Simulation and Experimental Methods.

Polymer grouting materials are increasingly used in the filling of mine fissures. Unlike conventional inorganic grouting materials, the self-expansion of polymers adds complexity to their diffusion process within the crack. The objective of this research was to examine how polymer grouting material spreads in cracks at ambient temperatures and pressure. The investigation involved conducting grouting tests and performing numerical fluid simulation calculations using the finite-volume method in the computational fluid dynamics software, ANSYS FLUENT 2022 R1. The fluid volume approach was employed to determine the boundary between fluid and air and to ascertain the variation patterns of density in the slurry and the fracture system. This study applied the principles of fluid mechanics to investigate the patterns of variation in the physical characteristics of polymer grouting materials, including their density, pressure, flow velocity, and movement distance, during the diffusion process. The results indicated that the density of the polymer grouting material decreased exponentially over time throughout the diffusion process. With the increase in the grouting's volume, the grout's pressure and the permeable distance of the grout increased. The slurry's pressure near the grouting hole exceeded the other points' pressure. The physical parameters of the slurry were numerically simulated by ANSYS FLUENT 2022 R1 software, and the results were compared with the experimental data. After comparing the numerical simulation results with the test data, it was clear that the numerical simulation method was superior in accurately predicting the distribution pattern of each parameter of the polymer slurry during diffusion. The grouting volume, pressure distribution, and real-time change in the position of the flow of slurry could be efficiently determined through numerical calculation and simulated grouting tests. This work can offer valuable information for designing polymer grouting materials used in underground mine fissures.

Fluid energy theory of membrane

Membrane science is the key strategy to solve water shortage in the future, and its essence is energy and mass transfer. Due to the complexity and variety of the internal structure of membrane, the energy transfer theory of membrane is still a black box theory. Herein, a new fluid mechanics principle is introduced to establish the energy fluid theory of membrane, which is translated into the energy formula: such as the initial total pressure difference (ΔP), the flow rate of fluid exiting the membrane (v1 and v2), fluid density (ρ), and energy consumption by salt resistance (NSR): { [Formula: see text] +12ρv23}. The theoretical framework is not only helpful for the data analysis of the energy transfer process of membranes, but also helps to allow for more in-depth and specific theoretical research. For instance, the relationship between NSR and the concentration difference (C) of salt can be expressed as NSR = aCb (a-product constant, b-exponential constant, R2>0.99). Hence, the basic theory can not only be widely applied to a variety of membranes with complex internal structure, but also have a profound impact on the application and research of membrane science.

Leveraging the fundamentals of heat transfer and fluid mechanics in microscale geometries for automated next-generation sequencing library preparation

Next-generation sequencing (NGS) is emerging as a powerful tool for molecular diagnostics but remains limited by cumbersome and inefficient sample preparation. We present an innovative automated NGS library preparation system with a simplified mechanical design that exploits both macro- and microfluidic properties for optimizing heat transfer, reaction kinetics, mass transfer, fluid mechanics, adsorption–desorption rates, and molecular thermodynamics. Our approach introduces a unique two-cannula cylindrical capillary system connected to a programmable syringe pump and a Peltier heating element able to execute all steps with high efficiency. Automatic reagent movement, mixing, and magnetic bead-based washing with capillary-based thermal cycling (capillary-PCR) are completely integrated into a single platform. The manual 3-h library preparation process is reduced to less than 15 min of hands-on time via optimally pre-plated reagent plates, followed by less than 6 h of instrument run time during which no user interaction is required. We applied this method to two library preparation assays with different DNA fragmentation requirements (mechanical vs. enzymatic fragmentation), sufficiently limiting consumable use to one cartridge and one 384 well-plate per run. Our platform successfully prepared eight libraries in parallel, generating sequencing data for both human and Escherichia coli DNA libraries with negligible coverage bias compared to positive controls. All sequencing data from our libraries attained Phred (Q) scores > 30, mapping to reference genomes at 99% confidence. The method achieved final library concentrations and size distributions comparable with the conventional manual approach, demonstrating compatibility with downstream sequencing and subsequent data analysis. Our engineering design offers repeatability and consistency in the quality of sequence-able libraries, asserting the importance of mechanical design considerations that employ and optimize fundamental fluid mechanics and heat transfer properties. Furthermore in this work, we provide unique insights into the mechanisms of sample loss within NGS library preparation assays compared with automated adaptations and pinpoint areas in which the principles of thermodynamics, fluid mechanics, and heat transfer can improve future mechanical design iterations.

Research on the Pressure Distribution Law of Synchronous Grouting in Shield Tunnels and the Force on Segments

The pressure distribution and the force on tunnel segments of synchronous grouting in the shield tail gap channel of shield tunnels are key to controlling the stability and surface settlement of the strata surrounding such tunnels. Based on the basic principles of fluid mechanics and the limit equilibrium method, this study establishes a mathematical model of synchronous grouting in shield tunnels, derives the expressions of the grouting pressure and the force on tunnel segments in the shield tail gap channel, and verifies them using an engineering case study. Studies have shown that the force on tunnel segments and the speed of shield excavation are increasing. An excessive shield excavation speed will cause the load on tunnel segments to increase, which exacerbates the uneven distribution of the grouting pressure. The force on tunnel segments and the grouting pressure also have a positive relationship with the thickness of the shield tail gap, but the impact is limited to a certain range. With an increase in the tunnel radius, the number of grouting holes should be appropriately increased to balance the water and soil pressure in the surrounding strata. These research results can provide a theoretical reference for the design of synchronous grouting for shield tunnels in the future.

Mathematical Modelling of Non-Stop Heron’s Fountain and its Practical Applications

Abstract: Heron’s fountain is one of the brilliant ideas given by Heron (Mathematician and Physicist) in which we get free kinetic energy to run our fountain. The schematic diagrams of the physical demonstration of the magic fountain are given in this paper. The fundamental work principles of magic fountain are hydraulics and Pneumatics. In engineering, it is important to analyze a system by developing mathematical models, so we used the principle of fluid mechanics and Bernoulli’s theorem to develop the equation for the velocity of a free jet. It is a very important thing in engineering to make use of energy, The free jet having kinetic can used for energy production purposes. In this paper, Mathematical Modelling and some fundamental applications of the non-stop fountain have been discussed. Heron’s fountain due to its perpetual nature has thrilling applications in the micro hydropower sector. Moreover, it has keen value in environmental sustainability and air pollution. The contribution of the fountain cannot be underestimated towards the beauty of buildings and relaxation of mind.

A Microfluidic Chip for Single-Cell Capture Based on Stagnation Point Flow and Boundary Effects.

The capture of individual cells using microfluidic chips represents a widely adopted and efficient approach for investigating the biochemical microenvironment of singular cells. While conventional methods reliant on boundary effects pose challenges in precisely manipulating individual cells, single-cell capture grounded in the principle of stagnation point flow offers a solution to this limitation. Nevertheless, such capture mechanisms encounter inconsistency due to the instability of the flow field and stagnation point. In this study, a microfluidic device for the stable capture of single cells was designed, integrating the principle of fluid mechanics by amalgamating stagnation point flow and boundary effects. This innovative microfluidic chip transcended the limitations associated with single methodologies, leveraging the strengths of both stagnation point flow and boundary effects to achieve reliable single-cell capture. Notably, the incorporation of capture ports at the stagnation point not only harnessed boundary effects but also enhanced capture efficiency significantly, elevating it from 31.9% to 83.3%, thereby augmenting capture stability. Furthermore, computational simulations demonstrated the efficacy of the capture ports in entrapping particles of varying diameters, including 9 μm, 14 μm, and 18 μm. Experiment validation underscored the capability of this microfluidic system to capture single cells within the chip, maintaining stability even under flow rate perturbations spanning from 60 μL/min to 120 μL/min. Consequently, cells with dimensions between 8 μm and 12 μm can be reliably captured. The designed microfluidic system not only furnishes a straightforward and efficient experimental platform but also holds promise for facilitating deeper investigations into the intricate interplay between individual cells and their surrounding microenvironment.

Experimental investigation of a novel high performance multi-walled carbon nano-polyvinylpyrrolidone/silicon-based shear thickening fluid damper

A novel high performance multi-walled carbon nano-polyvinylpyrrolidone/silicon-based shear thickening fluid (MWCNTs-PVP/SiO2-STF), abbreviated and subsequently referred to as MPS-STF, is developed in this paper. The rheological properties of the MPS-STF are investigated, and the viscosity model of MPS-STF is established. Furthermore, the MPS-STF based viscous fluid damper (MPS-STF-VFD) is designed according to the rheological characteristics of the novel fluid. The impact of loading frequencies, displacement amplitudes and the numbers of piston holes on the dynamic performance of the damper is studied through sophisticated multiple cases loading tests using MTS facility. The test results show that the loading frequency, displacement amplitudes and the number of piston holes have great influence on the rheological properties of MPS-STF. This directly affects the maximum damping force and heat dissipation capacity of MPS-STF-VFD. Finally, the mechanical model of the damper is established based on the principle of fluid mechanics. The simulation results agree well with the experimental data. The high damping performance of the MPS-STF-VFD can be achieved based on the characteristics of the modified fluid. Relevant results reported in this paper can provide an important solution for the development and application of damping technology in engineering structures.

ANALYSIS OF THE RESISTANCE TO THE ADVANCE OF THE HULL OF A BOAT IN WATERS OF THE SINU RIVER

The aim of this article is to determine the resistance to the advance of a boat in the waters of the Sinu River, using principles of fluid mechanics, with the help of computational tools such as Maxsurf and Ansys Fluent, validating the results with a scale model. The method consists of establishing dimensional relationships of the hull by creating 9 models with the help of Maxsurf Modeler with which the geometries are created and Maxsurf Resistance to determine the resistance to the advance. With the help of ANSYS Fluent the drag is determined using the selected model with Maxsurf Modeler. Finally, a scale model is built and tested in a test channel, thus validating the hull design to minimise the drag. For the resistance analysis it is concluded that the most influential relationship is the length to beam, with speeds between 0.5 and 1.5 m/s, the results obtained by the three methods are consistent, however, at speeds higher than 2.2 m/s, a significant divergence between the results is observed. This phenomenon highlights the importance of considering the specific speed range when assessing the boat’s drag in moving water such as a river.

气固耦合条件下多孔热风式茶叶杀青理条机数值模拟与性能试验

The gas–solid coupling of a porous hot-air tea de-enzyming and carding machine was studied by means of computational fluid dynamics and discrete element coupling. In the numerical model, the discrete phase of tea particles was simulated using Rocky-DEM software, while the gas phase was described by ANSYS Fluent software. A mathematical model of the movement characteristics of tea particles in air was established according to the principle of fluid mechanics, to carry out dynamic analysis of tea particles’ movement process and derive how the motion of gas and tea particles is governed. Three sets of prototype tests were carried out on the basis of the design and simulation, and the average of their results taken. This showed that the hourly output of the test prototype was 3.89 kg/h, the bar-type rate was 89.14%, the de-enzyming moderation rate was 91.67%, and the average value of the measured effective operating temperature of the pot slot was 189 °C. The performance of the prototype was also tested and analyzed. After conducting a tea sensory evaluation expert appraisal, the sensory evaluation indices of the prototype-processed tea satisfied all current market requirements, being superior to those of the conventional de-enzyming and carding machine. The quality of the finished tea also met the agronomic standards and the operational requirements of the de-enzyming and carding machine.

Magnetohydrodynamic effects on a pathological vessel: An Euler–Lagrange approach

For numerically studying blood flow in a pathological vessel under the influence of a magnetic field, it is necessary to develop an approach that tracks the moving tissue and accounts for interactions between the fluid, the arterial wall, and the magnetic field. The current study discusses a mathematical approach of the fluid's motion under the influence of a magnetic field using fluid mechanics principles. A mixed Euler–Lagrange formulation is introduced to mathematically describe the blood flow in the aneurysm during the entire cardiac cycle. Blood is considered a Newtonian, incompressible, and electrically conducting fluid, subjected to a static and uniform magnetic field. Generalized curvilinear coordinates are used to transform the transport equations into body-fitted geometries and provide a manageable form of equations. The system of equations related to motion consists of a coupled and nonlinear system of partial differential equations (PDEs). The discretization of the PDEs is performed using the finite volume method. The addition of the Lorentz force in the momentum PDEs describes the applied uniform magnetic field in the blood flow. Due to strong coupling and nonlinear terms, a simultaneous solution approach is applied. The results show that the magnetic field strongly influences blood flow, reducing the velocity field q¯ and increasing the pressure drop, Δp.

Fluid Mechanics of Droplet Spreading of Chitosan/PVA-Based Spray Coating Solution on Banana Peels with Different Wettability.

The spreading behavior of a coating solution is an important factor in determining the effectiveness of spraying applications. It determines how evenly the droplets spread on the substrate surface and how quickly they form a uniform film. Fluid mechanics principles govern it, including surface tension, viscosity, and the interaction between the liquid and the solid surface. In our previous work, chitosan (CS) film properties were successfully modified by blending with polyvinyl alcohol (PVA). It was shown that the mechanical strength of the composite film was significantly improved compared to the virgin CS. Here we propose to study the spreading behavior of CS/PVA solution on fresh bananas. The events upon droplet impact were captured using a high-speed camera, allowing the identification of outcomes as a function of velocity at different surface wettabilities (wetting and non-wetting) on the banana peels. The mathematical model to predict the maximum spreading factor, βmax, was governed by scaling law analysis using fitting experimental data to identify patterns, trends, and relationships between βmax and the independent variables, Weber (We) numbers, and Reynolds (Re) numbers. The results indicate that liquid viscosity and surface properties affect the droplet's impact and spreading behavior. The Ohnesorge (Oh) numbers significantly influenced the spreading dynamics, while the banana's surface wettability minimally influenced spreading. The prediction model reasonably agrees with all the data in the literature since the R2 = 0.958 is a powerful goodness-of-fit indicator for predicting the spreading factor. It scaled with βmax=a+0.04We.Re1/3, where the "a" constants depend on Oh numbers.

Workability Properties of Specified Density Concrete with Municipal Solid Waste Incinerator Tailings Added as a Lightweight Aggregate

The application of municipal solid waste incineration tailings lightweight aggregate (MSWI-TLA) for reducing carbon emissions, energy consumption, and environmental pollution of bulk solid waste treatment has received extensive attention. As a new type of green lightweight aggregate, MSWI-TLA exhibits considerably good performance and broad prospects; however, its working performance in cement-based materials is not as good as that of ordinary aggregates. In this study, a standardized municipal solid waste incineration tailings lightweight fine aggregate (MSWI-TLFA) with a fineness modulus of 3.1 and a municipal solid waste of 10 mm were utilized as substitutes for the common aggregate. The incineration tailings lightweight coarse aggregate (MSWI-TLCA) with the particle size ranging from 5 to stirring process and the fluidity and filling properties were improved, and stratification was slowed down. Based on the slump, fluidity, and stratification data of municipal solid waste incineration tailings lightweight aggregate specific density concrete (MSWI-TLA-SDC), the internal and external stacking structure model, matrix density three-phase diagram, and stratification function relationship were established, and the formation mechanism of fluidity and homogeneity under the synergistic effect of MSWI-TLA-SDC matrix density was revealed. Simultaneously, the qualitative analysis of homogeneity was carried out intuitively and visualized using computed tomography (CT) technology, and the accurate quantitative analysis model of stratification degree and aggregate separation factor was established using the principle of fluid mechanics, and the optimization effect was verified. The results show that the fluidity of MSWI-TLA-SDC decreases by 3.3%–30.5% and the delamination degree increases by 4.9%–22.9% compared with ordinary concrete. The main reason for the poor fluidity and homogeneity of MSWI-TLA-SDC is the poor density synergy between tailings lightweight aggregate, ordinary aggregate, and mortar matrix. The preabsorbed gravel-type small-size tailings lightweight aggregate along with technical measures like combining water-reducing agent, fine tailings aggregate, and tailings powder can be used to reduce the difference in matrix density and fully exploit the synergistic effects of matrix density. For the closed-loop absorption of tailings lightweight aggregate as well as the technical advancement and promotion of MSWI-TLA-SDC, it is crucial to increase the fluidity and homogeneity of MSWI-TLA-SDC.

The Application of Fluid Mechanics in Engineering

Whether an item is popular or not depends largely on its cost performance. For manufacturers, it is very important to create the most high-quality items with the least amount of money. For example, in the case of the same material, what kind of bridge structure is the most material-saving and long-life, what specific design can make the car more fuel-efficient and faster, and what kind of special pipeline design can make the flow of water resources more efficient are problems that manufacturers need to constantly explore, and fluid mechanics can help and solve these problems to a large extent. This paper mainly introduces the application of fluid mechanics in bridge engineering, automobile design, and agricultural production. The author analyzes the working principle of fluid mechanics, including some speculations on the future development direction of fluid mechanics.