Hydrodynamic Properties Research Articles

Prediction of hysteretic soil and water characteristic curve of loess based on multifractal theory and improved physical statistics

Soil and water characteristic curve (SWCC) is an important soil parameter which is used to estimate various parameters to describe unsaturated soil hydrodynamic properties. Due to the large span of soil matric suction, this procedure is time-consuming and difficult to measure it in the laboratory. However it is of great significance to find a scientifically efficient and economically viable method to predict SWCC of loess soil. Based on the measurement of soil–water characteristic curves in the laboratory, this study predicted the drying curve (DC) based on the soil particle size distribution (PSD) fractal theory. It also used the domain model to predict the wetting curve (WC) based on the pore distribution, and finally obtained the complete soil–water characteristic curve of loess. These procedures improved the research status which using the drying curve to instead of the wetting curve, and this replace usually leads to a large calculation error and underestimates the safety of the slope. The method proposed in this study can quickly obtain the hysteretic soil–water characteristic curve of loess based on only the soil particle size distribution, improve the correlative calculation accuracy of unsaturated loess, and play an important role in predicting the hydraulic parameters of loess soil.

REWORKED MESOZOIC RADIOLARIANS IN MIOCENE-PLIOCENE FORELAND SEDIMENTS IN THE ZAGROS BELT, IRAN

Micropaleontology can give important insights into the provenance and paleoenvironmental conditions in terrestrial sedimentary archives. For the current study, 84 samples representing a 2.6 km thick sedimentary profile from the SimplyFolded Zagros Mountain Belt were investigated. They span ca. 10.2 my from the late Middle Miocene (Serravallian) to the earliest Pleistocene (Gelasian), and comprised floodplain sediments and saline mudstones with an aeolian contribution. The mudstones revealed a unique Cretaceous radiolarian assemblage comprising largely of cryptothoracic Nassellarians and spherical spumellarians. This record highlights the reworking of sediments derived from Cretaceous Qulqula- Kermanshah radiolarian claystones and radiolarites in the Imbricated Zagros belt into the distal Neogene Zagros foreland sediments in Lurestan (Lurestan Arc). The high abundance of Holocryptocanium barbui (Dumitrica) and other cryptothoracic taxa compared to the Qulqula- Kermanshah radiolarian claystones and radiolarites potentially indicates a preferred erosion of softer units such as the Red Radiolarian Claystone Unit (RRCU) compared to harder radiolarian cherts. The observation of a reworked largely cryptothoracic assemblage might also point to additional sorting effects during fluvial and aeolian transport as well as during redeposition, depending on the morphology and hydrodynamic properties of individual radiolarian taxa.

CO2 capture in a novel rotating spiral contactor with hydraulic seal: Hydromechanics, mass transfer and modeling

The efficient capture of CO2 has always been a goal pursued by people. However, low gas handling capacity and low gas–liquid ratio restricts existing gas–liquid contactors, especially for non-rotating ones. In this study, a gas–liquid contactor with high gas handling capacity and high gas–liquid ratio, the rotating spiral contactor, was developed. Hydrodynamic properties of the contactor were experimentally or theoretically investigated. A novel interface model was developed to describe gas–liquid interface shape. CO2 capture using MEA/DMEA aqueous solution were evaluated in terms of space–time yield (τ), overall volumetric mass transfer coefficient (KGae) and CO2 capture efficiency (η). A rate-based model was developed and applied for the first time to predict CO2 capture in the rotating spiral contactor. The hydrodynamic results showed that liquid layer thickness was below 400 μm for the liquid with viscosity of 14.5 mPa.s. Under the rotational speed of 1200 rpm, the gas–liquid ratio ranged from 525 to 2700, while the gas–liquid surface area remained around 667 m2/m3. The interface model predicted interface thickness within a relative deviation of ± 20 %. The results also showed that τ, KGae and η respectively were 3428–17021 h−1, 1.0–6.4 kmol.m−3.h−1.kPa−1 and 38–98 % at the gas–liquid ratio range of 200–1000. The predicted KGae and η by rate-based model agreed well with the experimental data within a relative deviation of ± 15 %. This rotating spiral contactor is ideally suitable for the scenarios with large gas handling requirement and high gas–liquid ratio.

Hydrodynamic properties of the perfect hard-sphere crystal: microscopic computations with Helfand moments

Within the framework of the local equilibrium approach, the equilibrium and nonequilibrium properties relevant to the hydrodynamics of the perfect hard-sphere crystal were obtained through molecular dynamics simulations using the Helfand moments associated with momentum and energy transport. Because this crystal is face-centered cubic, the hydrodynamic properties we considered were hydrostatic pressure, isothermal bulk modulus, specific heat capacities and their ratio, three isothermal elastic constants (C11T,C12T,C44T) , heat conductivity, and three viscosities (η11,η12,η44) (in Voigt’s notation). These properties were computed as a function of the particle density. The pressure and transport coefficients diverge near the close-packing density, as the collision frequency per particle also diverges.

Velocity and load dependent dynamic shock absorber friction at stationary conditions

When it comes to vehicle vertical dynamics, the characteristics of shock absorbers are of high importance. With the increasing use of active suspension systems, it becomes possible to adapt the hydraulic damping force to the road event, while the friction force is not controllable. As a result, friction becomes more relevant and can negatively affect passenger ride comfort. In many mechanical applications, it is observed that friction in lubricated sliding conditions is velocity and load dependent. In contrast, shock absorber friction, and therefore suspension friction, is commonly considered as quasi-static, i.e. characterised by a constant potential. Since the shock absorber is predominantly in motion over a wide velocity range, it is necessary to improve the understanding of friction characteristics especially in the dynamic domain. In this study, modified valve-free shock absorbers are presented that allow the observation of dynamic friction properties experimentally. As not covered by previous studies, the effect of side force (load) as a main parameter to increase friction is investigated. It is observed that its effect varies significantly with velocity and alters the stationary friction-velocity curve, also known as the Stribeck curve. In addition, the shape of the Stribeck curve depends strongly on the shock absorber's oil volume. These novel results emphasise a substantial, interdependent influence of load and velocity on the (elasto-)hydrodynamic properties of the dynamic shock absorber friction force, which was not identified in the literature. The dynamic friction force exceeds the quasi-static friction force multiple times, and also exceeds the hydraulic damping force for considerable side forces in the lower velocity range up to 60 mm/s. Consequently, the total shock absorber force under presence of side force is determined. The findings can be used to improve active suspension control or to improve vehicle simulation by enabling the parametrisation of dynamic shock absorber friction models.

Polyimide (PI) Composite Spunlace Nonwovens for Hygiene Material with Excellent Comfort and Antimicrobial Properties

Nonwoven fabrics with appropriate hydrophilicity and potent antimicrobial properties hold important promise for hygiene applications. However, existing materials with certain limitations and complex manufacturing steps, along with the unavoidable use of chemicals in the process, are limited to a certain extent in terms of the balance between comfort and antimicrobial properties. In this paper, a polyimide (PI) fiber was reported to be used for the preparation of PI composite nonwoven fabrics (5-P), which can effectively enhance the surface hydrodynamic and antimicrobial properties of the nonwoven by a one-step plasma treatment on one side. After treatment, the one-sided water contact angle (WCA) changed from 121.5° to 68.5°, and the permeation volume from 0.7 to 2.1 g, with a relative increase of 181.9%. Meanwhile, the reverse osmosis amount was only 0.5 g, achieving rapid permeation while keeping a low reverse osmosis amount. The antimicrobial experiment showed that plasma-treated 5-P exhibited 64.3% and 91.6% inhibitory properties against Escherichia coli and Staphylococcus aureus, respectively. Notably, the production process of antimicrobial 5-P was fast and efficient without the addition of any chemicals. This method has great potential for the industrial preparation of antimicrobial comfort materials on a large scale, which is competitive in the medical, sanitary materials, and personal care fields.

Numerical analysis of accelerating and decelerating ducts modified by camber on the unsteady flow field of pump-jet

Utilizing the Reynolds-averaged Navier-Stokes equations method in conjunction with Detached Eddy Simulation model, this paper investigates effects of duct camber (f) on transient hydrodynamic characteristics, particularly propulsion performance and flow field behavior. The research begins by validating the numerical methodology through experimental and numerical assessments of propeller VP1304 and a pump-jet operating under mooring conditions. The exploration commences with examining propulsion characteristics, followed by analyzing time-domain and frequency-domain data, wherein thrust fluctuations and pulsating pressures are scrutinized via fast Fourier transform (FFT). The pressure distribution and velocity field are subsequently presented to unveil the mechanisms triggered by variations in f. Comparative findings highlight that in cases of pump-jets with lower camber, the outlet velocity exceeds the inlet velocity, a trend contrary to scenarios involving higher f values. Additionally, by analyzing vorticity magnitude distribution and vortices, this study attains comparative insights into the effects of accelerating and decelerating ducts on rotor and stator trailing vortices, offering a window into the flow instability mechanism amidst diverse duct configurations. The results showcased to demonstrate the substantial impact of f variation on hydrodynamic properties. This comprehensive investigation yields practical guidance for the optimal design of pump-jets, potentially informing future design endeavours.

Effect of Heat Source on MHD Convective Flow of Non- Newtonian Fluid past an Oscillating Porous Plate in Porous Medium

Introduction: An investigation was conducted to analyse the impact of unsteady flow caused by non-Newtonian fluid with magneto hydrodynamic properties on an oscillating plate made of porous material in a porous medium. The analysis of convective heat transfer included additional parameters such as electrically conducting unsteady flow-facing applied magnetic force. The Perturbation method was used to transform the governing equations into non-linear differential equations with utmost precision. Moreover, MATLAB was used to precisely evolve temperature and velocity profiles for different parameters such as Grashof number, Prandtl number, skin friction, magnetic parameter, and source/sink. The heat transfer rate was thoroughly evaluated and compiled using graphs and tables, guaranteeing the accuracy of the results.

Flexible structural arrangement and DNA-binding properties of protein p6 from Bacillus subtillis phage φ29.

The genome-organizing protein p6 of Bacillus subtilis bacteriophage φ29 plays an essential role in viral development by activating the initiation of DNA replication and participating in the early-to-late transcriptional switch. These activities require the formation of a nucleoprotein complex in which the DNA adopts a right-handed superhelix wrapping around a multimeric p6 scaffold, restraining positive supercoiling and compacting the viral genome. Due to the absence of homologous structures, prior attempts to unveil p6's structural architecture failed. Here, we employed AlphaFold2 to engineer rational p6 constructs yielding crystals for three-dimensional structure determination. Our findings reveal a novel fold adopted by p6 that sheds light on its self-association mechanism and its interaction with DNA. By means of protein-DNA docking and molecular dynamic simulations, we have generated a comprehensive structural model for the nucleoprotein complex that consistently aligns with its established biochemical and thermodynamic parameters. Besides, through analytical ultracentrifugation, we have confirmed the hydrodynamic properties of the nucleocomplex, further validating in solution our proposed model. Importantly, the disclosed structure not only provides a highly accurate explanation for previously experimental data accumulated over decades, but also enhances our holistic understanding of the structural and functional attributes of protein p6 during φ29 infection.

Global sensitivity analysis of the dynamics of a distributed hydrological model at the catchment scale

The PESHMELBA model simulates water and pesticide transfers at the catchment scale. Its objective is to help the process of decision making in the common management of long-term water quality. Performing the global sensitivity analysis (GSA) of this type of model is necessary to trace the output variability to the input parameters. The goal of the present work is to perform a GSA, while considering the spatio-temporal nature and the high dimensionality of the model. The output considered is the surface moisture simulated over a two-month period on a catchment of assorted mesh elements (plots). The GSA is performed on the dynamical outputs, rewritten through their functional principal components. Sobol’ indices are then estimated through polynomial chaos expansion on each principal component. The analysis differs between the two types of behaviour observed in the surface moisture outputs. The hydrodynamic properties of the surface soil have a dominant influence on the average surface moisture. Nonetheless, the parameters describing deeper soil layers influence the output dynamics of those plots where the surface moisture is saturated. We obtain Sobol’ indices with high precision while using a limited number of model estimations and considering the models spatio-temporal nature. The physical interpretation of the GSA confirms and augments our knowledge on the model.

Hydrodynamic and heat transfer characteristics of two circular cylinders in series under two-degrees-of-freedom vortex-induced vibration

The heat transfer and hydrodynamic properties of two rigid cylinders in series with fluid disturbance at the laminar flow under vortex-induced vibration were studied numerically. The six DOF model was chosen and combined with user-defined functions (UDF) to seek a solution for the cylindrical equations of motion. The coupled calculation between fluid flow and rigid body motion was realized by combining the dynamic mesh technique. The effects of two types of motion conditions of the upstream cylinder, i.e. fixed (referred to as model A) and with two degrees-of-freedom (referred to as model B), on the flow field and heat transfer of the downstream cylinder with two degrees-of-freedom were investigated. The numerical results showed that in the reduced velocity (Ur ) range considered in this work, the heat transfer and motion conditions of the downstream cylinder were subjected to the self-shedding vortices and the shedding vortices of the upstream cylinder. The comparison of models A and B at Ur = 4 and Ur = 5, respectively, displayed that the force frequency of the downstream cylinder was close to the natural frequency when it was impacted by the tail vortices shedding of the upstream cylinder and the self-shedding vortices. This resulted in the maximum transverse amplitude and strongest heat transfer of the downstream cylinder.

Hyperbranched TEMPO-based polymers as catholytes for redox flow battery applications.

Application of redox-active polymers (RAPs) in redox flow batteries (RFBs) can potentially reduce the stack cost through substitution of costly ion-exchange membranes by cheap size-exclusion membranes. However, intermolecular interactions of polymer molecules, i.e., entanglements, particularly in concentrated solutions, result in relatively high electrolyte viscosities. Furthermore, the large size and limited mobility of polymers lead to slow diffusion and more sluggish heterogeneous electron transfer rates compared to quickly diffusing small molecules. Although a number of RAPs with varying electrolyte viscosities have been reported in the literature, the relation between the RAP structure and the hydrodynamic properties has not been thoroughly investigated. Herein, hyperbranched 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO)-based polymers intended for application as low-viscosity catholytes for RFBs are presented and the influence of the structure and the molar mass distribution on the hydrodynamic properties is investigated. A new synthesis approach for TEMPO-based polymers is established based on step-growth polymerization of a TEMPO-containing monomer using an aza-Michael addition followed by a postpolymerization modification to improve solubility in aqueous solutions. The compact structure of hyperbranched polymers was demonstrated using size-exclusion chromatography (SEC) with viscometric detection and the optimum molar mass was found based on the results of viscometric and crossover investigations. The resulting RAP revealed a viscosity of around 21 mPas at a concentration corresponding to around 1 M TEMPO-containing units, according to the calculated mass of the repeating unit, showing potential for high capacity polymer-based catholytes for RFBs. Nevertheless, possible partial deactivation of TEMPO units lowered the active TEMPO concentration of the hyperbranched RAPs. A faster diffusion and higher charge transfer rate were observed for the hyperbranched polymer compared to the previously reported linear polymers. However, in RFB tests, a poor performance was observed, which is attributed to the side reactions of the oxidized TEMPO moieties. Finally, pathways for overcoming the main remaining challenges, i.e., high loss of material during dialysis as an indication of being prone to crossover, the partial deactivation of TEMPO moieties, and the subsequent side reactions under battery conditions, are suggested.

ПРИНЦИПЫ, ОБЩАЯ СХЕМА И ОБОСНОВАНИЕ ЭФФЕКТИВНОСТИ ТЕПЛОПЕРЕДАЧИ ПРИ ПРОИЗВОДСТВЕ МЯСНЫХ ПРОДУКТОВ ПИТАНИЯ

The article studies flow chart development for production line of liquid packaged broths in the form of a finished fast-food product. It reports on the results of analytical justification of technological operations and heat transfer process of meat cooking in liquid packaged broths production. The research was based on theoretical analysis of thermal conductivity patterns from hydrodynamic and capacitive properties of medium and processed product. Based on the results of the study, closed flow line was developed, being an integral structured system. It includes all technological process operations and their interaction in complex in liquid packaged broth production. Optimization of continuous process operations ensures high sterility, liquid broth quality and resource economy.

First order event plane correlated directed and triangular flow in Au+Au collisions from BES-II at STAR

In heavy-ion collisions, the measurements of anisotropic flow coefficients (vn) offer insights into collective hydrodynamic expansion and transport properties of the produced medium at higher collision energies, while also being sensitive to the compressibility of the nuclear matter and nuclear equation of state at lower collision energies. In this contribution, we present the measurement of charged particle v1 over ten units of pseudorapidity (η) in Au+Au collisions at √SNN = 27 and 19.6 GeV and compare it with multiple model calculations. Only UrQMD was able to reproduce a sizable v1 at the forward pseudorapidity as observed in the experiment. We also present the results of v1 and v3 at √SNN = 3 - 3.9 GeV for identified hadrons and light nuclei with respect to Ψ1. The results are compared with theoretical models to identify the source of nonzero v3{Ψ1} and to demonstrate its vital connection to the equation of state.

Studies of the hydrodynamic properties of the formation of an oil and gas condensate field

This paper presents the experience of well testing conducted by several geological associations. The studies were conducted to assess the characteristics of productive formations, such as hydroconductivity, productivity, saturation pattern and operating mode. Various methods and equipment were used, including various types of drilling rigs and drills. Some disadvantages of the tests are also described, such as the erroneous choice of perforation intervals or poor-quality gas condensate studies. The data on the tools and techniques used, as well as the results of studies on stationary and unsteady filtration modes are presented. The findings of the study will help to improve understanding of the geological characteristics of the formations and improve production efficiency.

Dilute polyelectrolyte solutions: recent progress and open questions.

Polyelectrolytes are a class of polymers possessing ionic groups on their repeating units. Since counterions can dissociate from the polymer backbone, polyelectrolyte chains are strongly influenced by electrostatic interactions. As a result, the physical properties of polyelectrolyte solutions are significantly different from those of electrically neutral polymers. The aim of this article is to highlight key results and some outstanding questions in the polyelectrolyte research from recent literature. We focus on the influence of electrostatics on conformational and hydrodynamic properties of polyelectrolyte chains. A compilation of experimental results from the literature reveals significant disparities with theoretical predictions. We also discuss a new class of polyelectrolytes called poly(ionic liquid)s that exhibit unique physical properties in comparison to ordinary polyelectrolytes. We conclude this review by listing some key research challenges in order to fully understand the conformation and dynamics of polyelectrolytes in solutions.

Relativistic shocks in conductive media

Context. Relativistic shocks are present in all high-energy astrophysical processes involving relativistic plasma outflows interacting with their ambient medium. While they are well understood in the context of relativistic hydrodynamics and ideal magnetohydrodynamics (MHD), there is a limited understanding of the properties related to their propagation in media characterized by finite electrical conductivity. Aims. This work presents a systematic method for the derivation and solution of the jump conditions for relativistic shocks propagating in MHD media with finite electrical conductivity. This method is applied to the numerical solution of the Riemann problem and the determination of the conditions inside the blastwave that is formed when ultrarelativistic magnetized ejecta interact with the circumburst medium during a gamma-ray burst. Methods. We derived the covariant relations expressing the jump conditions in a frame-independent manner. The resulting algebraic equations expressing the Rankine-Hugoniot conditions in the propagation medium’s frame were then solved numerically. A variable adiabatic index equation of state was used in order to obtain a realistic description of the post-shock fluid’s thermodynamics. This method was then employed for the solution of the Riemann problem for the case of a forward and a reverse shock, both of which form during the interaction of a gamma-ray burst ejecta with the circumburst medium. This allowed us to determine the kinematics of the resulting blastwave and the dynamical conditions in its interior. Results. Our solutions clearly depict the impact of the plasma’s electrical conductivity in the properties of the post-shock medium. Two characteristic regimes are identified with respect to the value of a dimensionless parameter that has a linear dependence on the conductivity. For small values of this parameter, the shock affects only the hydrodynamic properties of the propagation medium and leaves its electromagnetic field unaffected. No current layer forms in the shock front; thus, we refer to this as the current-free regime. For large values of this parameter, the ideal MHD regime has been retrieved. We also show that the assumption of a finite electrical conductivity can lead to higher efficiencies in the conversion of the ejecta energy into thermal energy of the blastwave through the reverse shock. The theory developed in this work can be applied to the construction of Riemann solvers for resistive relativistic MHD (RR4MHD).

Electrophoresis, a transport technology that transitioned from moving boundary method to zone method.

Gel electrophoresis, a transport technology, is one of the most widely used experimental methods in biochemical and pharmaceutical research and development. Transport technologies are used to determine hydrodynamic or electrophoretic properties of macromolecules. Gel electrophoresis is a zone technology, where a small volume of sample is applied to a large separation gel matrix. In contrast, a seldom-used electrophoresis technology is moving boundary electrophoresis, where the sample is present throughout the separation phase or gel matrix. While the zone method gives peaks of separating macromolecular solutes, the moving boundary method gives a boundary between solute-free and solute-containing phases. We will review electrophoresis as a transport technology of zone and moving boundary methods and describe its principles and applications.

Integrated evaluation of biomechanical and biological properties of the biomimetic structural bone scaffold: Biomechanics, simulation analysis, and osteogenesis

A porous structure is essential for bone implants because it increases the bone ingrowth space and improves mechanical and biological properties. The biomimetically designed porous Voronoi scaffold can reconstruct the structure and function of cancellous bone; however, its comprehensive properties need to be investigated further. In this study, algorithms based on scaling factors were used to design the Voronoi scaffolds. Classic approaches, such as computer-aided design and the implicit surface method, have been used to design Diamond, Gyroid, and I-WP scaffolds as controls. All scaffolds were prepared by selective laser melting of titanium alloys and three-dimensional printing. Mechanical tests, finite element analysis, and in vitro and in vivo experiments were performed to investigate the biomechanical, cytologic, and osteogenic performance of the scaffolds, while computational fluid dynamics simulations were used to explore the underlying mechanisms. Diamond scaffolds have a better loading capacity, and the mechanical behaviors and fluid flow of Voronoi scaffolds are similar to those of the human trabecular bone. Cells showed more proliferation and distribution on the Diamond and Voronoi scaffolds and exhibited evident differentiation on Gyroid and Voronoi scaffolds. Bone formation was apparent on the inner part of the Gyroid, the outer part of the I-WP, and the entire Diamond and Voronoi scaffolds. The hydrodynamic properties and stimulus response of cells influenced by the porous structure account for the varied biological performance of the scaffolds. The Voronoi scaffolds with bionic mechanical behavior and an appropriate hydrodynamic response exhibit evident cell growth and osteogenesis, making them preferable for porous structural bone implants.

Energy spectrum analysis on a red blood cell model.

It is important to understand the dynamics of red blood cells (RBCs) in blood flow. This requires the formulation of coarse-grained RBC models that reproduce the hydrodynamic properties of blood accurately. One of the models that successfully reproduces the rheology and morphology of blood has been proposed by Fedosov et al. [Comput. Methods Appl. Mech. Eng. 199, 1937-1948 (2010)]. The proposed RBC model contains several parameters whose values are determined by either various experiments or physical requirements. In this study, we developed a new method of determining parameter values precisely from the fluctuations of the RBC membrane. Specifically, we studied the relationship between the spectra of the fluctuations and model parameters. Characteristic peaks were observed in the spectra, whose peak frequencies were dependent on the parameter values. In addition, we investigated the spectra of the radius of gyration. We identified the peaks originating from the spring potential and the volume-conserving potential appearing in the spectra. These results lead to the precise experimental determination of the parameters used in the RBC model.