Fluid Resistance Research Articles

Horizontal Magnetic Field Influence on Fluid Flow Across a Variable Thickness Rotating Disk With Stretching and Melting Phenomenon

ABSTRACTAn incompressible steady‐state flow of viscous fluid subjected to a variable thickness rotating surface is examined. The laminar flow stream is also affected by the disk stretching. A horizontal magnetic field is applied along the disk to stabilize the flow dynamics depending on its orientation and strength. The implication of a horizontal magnetic field is also effective in regulating the thermal energy in high‐temperature environments such as turbines and nuclear reactors. The thermal features are also characterized by thermal radiation and melting heating. The melting phenomenon is useful in phase‐change materials for efficient thermal storage and release like polymer molding or metal casting. Similarity transformations that account for the variable thickness of the disk surface are utilized to dimensionalize the flow equations and to obtain a self‐similar solution. The numerical scheme Runge‐Kutta‐Fehlberg (RKF‐45) built‐in package is used for the solution of the normalized flow model. The salient nature of the physical parameters is illustrated in the momentum and thermal fields. The numerical data on skin‐friction coefficient and local Nusselt number at the stretchable surface is also calculated. The graphical results indicate that the flow and temperature profiles are strongly influenced by the physical parameters under consideration. It can be deduced that melting decreases the fluid resistance close to the surface, reducing drag, and in turn increasing flow velocity. The latent energy absorbed during the melting process reduces the effective thermal energy into the fluid that reduces the temperature gradients in the thermal boundary layer flow. The stabilizing effect of the horizontal magnetic field on the flow phenomenon along the radial direction is observed for the angle varying from 0 to 30 degrees. It is seen that the dimensionless radius facilitates the thermal transport phenomenon from the disk surface to the fluid, thus resulting in reduction of the thermal field.

Impact of the oxide layer and subsurface micromechanical properties of laser peened 31L stainless steel on biocorrosion resistance in simulated body fluid

Impact of the oxide layer and subsurface micromechanical properties of laser peened 31L stainless steel on biocorrosion resistance in simulated body fluid

FLOW RESISTANCE STUDY OF POROUS MEDIA BASED ON FIVE SPHERE MODEL

Flow resistance in porous media has been a challenging research topic. It has extremely important applications in many fields, such as energy, chemical industry, metallurgy, petroleum, materials, and nuclear reactors. However, it is difficult and hot to calculate the flow resistance. This paper presents the innovative five-sphere model by employing the capillary flow, pore-throat, and flowing-around models. The flow resistance of the five-sphere model incorporates capillary flow resistance, local resistance caused by the changes of pore-throat, and flowing-around resistance of fluids around the filling material, which is summarized to derive a formula for the flow resistance of porous media without empirical parameters. On the basis of 42 sets of experimental data obtained from the literature, this paper compares and validates the proposed model. When Re<sub>p</sub> < 30, the five-sphere model is compared with the Carman equation and the Ergun and WuJinsui equation; when Re<sub>p</sub> > 30, the comparison is made with the Ergun and WuJinsui equation. Of the 22 data sets with deviations in the range of 0% to 30%, the five-sphere model equation for particles had an average diameter of 0.2 to 56.8 mm, porosity ranging from 0.32 to 0.4174, superficial velocities ranging from 0.000038 to 0.5342 m/s, and Reynolds number ranging from 0.124 to 10,730. Through further analysis of viscous and inertial resistance, it was found that viscous resistance losses from capillary flow and flowing around contribute the most; when Re<sub>p</sub> is < 30, inertial resistance losses from diameter change, and flowing around contribute the most when Re<sub>p</sub> > 150. This further confirms that flowing around occupies an important position in the flow resistance of porous media.

Radiation and heat generation effect on MHD natural convection in hybrid nanofluid-filled inclined wavy porous cavity incorporating a cross-shaped obstacle

Purpose This paper aims to explore, through a numerical study, buoyant convective phenomena in a porous cavity containing a hybrid nanofluid, taking into account the local thermal nonequilibrium (LTNE) approach. The cavity contains a solid block in the shape of a cross (+). It will be helpful to develop and optimize the thermal systems with intricate geometries under LTNE conditions for a variety of applications. Design/methodology/approach To attain the objective, the system governing partial differential equations (PDEs), expressed as functions of the current function and temperature, and are solved numerically by the finite difference approach. The authors carefully examine the heat transfer rates and dynamics of the micropolar hybrid nanofluid by presenting fluid flow contours, isotherms of the liquid and solid phases, as well as contours of streamlines, isotherms and concentration of the fluid. Key parameters analyzed include heated length (B = 0.1–0.5), porosity (ε = 0.1–0.9), heat absorption/generation (Q = 0–8), length wave (λ = 1–3) and the interphase heat transfer coefficient (H* = 0.05–10). The equations specific to the flow of a micropolar fluid are converted into classical Navier–Stokes equations by increasing the porosity and pore size. Findings The results showed that the shape, strength and position of the fluid circulation are dictated by the size of the inner obstacle (B) as well as the effective length of the heating wall. The lower value of obstruction size, as well as heating wall length, leads to a higher rate of heat transfer. Heat transfer is much higher for the higher amount of heat absorption instead of heat generation (Q). The higher porosity values lead to lesser fluid resistance, which leads to a superior heat transfer from the hot source to the cold walls. The surface waviness of 4 leads to superior heat transfer related to any other waviness. Research limitations/implications This work can be further investigated by looking at thermal performance in the existence of various-shaped obstructions, curvature effects, orientations, boundary conditions and other variables. Numerical simulations or experimental studies in different multiphysical contexts can be used to achieve this. Practical implications Many technical fields, including heat exchanging unit, crystallization processes, microelectronic units, energy storage processes, mixing devices, food processing, air conditioning systems and many more, can benefit from the geometric configurations investigated in this study. Originality/value This work numerically explores the behavior of micropolar nanofluids (a mixture of copper, aluminum oxide and water) within a porous inclined enclosure with corrugated walls, containing a solid insert in the shape of a cross in the center, under the oriented magnetic field, by applying the nonlocal thermal equilibrium model. It analyzes in detail the heat transfer rates and dynamics of the micropolar nanoliquid by presenting the flow patterns, the temperature of liquid and solid phases, as well as the variations in the flow, thermal and concentration fields of the fluid.

Investigation of the microstructural characteristics of laser-cladded Ti6Al4V titanium alloy and its corrosion behavior in simulated body fluid

Laser cladding technology has a wide range of potential industrial applications in the surface strengthening, repair and reuse of orthopedic implants. By employing this technique to conduct same-material surface restoration and enhancement on titanium alloys, it demonstrates significant developmental potential. However, the microstructure of laser additively manufactured titanium alloy differs significantly from that of traditional titanium alloys, which affects its corrosion resistance in human body fluids. To compare the corrosion resistance differences between the cladding layer and the substrate, this study investigates the microstructure of multi-pass laser cladding Ti6Al4V (TC4) titanium alloy and analyzes the corrosion morphology and corrosion products of the cladding layer in simulated body fluids (SBF). By comparing the electrochemical corrosion behavior of laser cladding with that of traditionally manufactured TC4, this research reveals the differences in corrosion resistance between the two titanium alloys. The research demonstrates that the microstructure of cladding primarily consists of prior-β grains and continuous grain boundary α phase, along with a complex basketweave structure composed of fine acicular α phase and lamellar α phase. Additionally, due to the complex thermal cycling process, the acicular α' colonies within the prior-β grains. These features enhance the cladding layer’s resistance to plastic deformation and increase microhardness, though with some uneven distribution. Interestingly, the TC4 cladding layer forms a porous passivation layer after corrosion, primarily composed of a TiO2 passivation film and deposits of hydroxyapatite and other phosphates. Due to the lower β-phase content, finer grains with higher energy states, and a greater proportion of high-angle grain boundaries (HAGBs) in the cladding layer, it exhibits higher electrochemical activity. As a result of these microstructural differences, the corrosion resistance of the TC4 cladding layer in SBF is inferior to that of TC4 manufactured using traditional techniques.

Interdisciplinary studies on a distribution property of tomato fruit: What is the initial abnormal response of their chilling injury occurrence?

Tomatoes develop chilling injury after low-temperature storage, which is often indicated by ion leakage from the tissues caused by cell membrane damage. However, the chilling injury causes a decline in tomato quality, which was already serious due to ion leakage. This study assumed that other physiological reactions precede cell membrane damage in tomatoes exposed to chilling stress. This hypothesis was investigated by measuring several physical, chemical and physiological parameters of tomatoes. Using samples stored at 2 or 5°С without chilling injury-induced cell membrane damage, this study confirmed other abnormal physiological reactions, such as ethylene production, respiration, electrochemical resistance in extracellular fluids, gene expression of heat shock protein, succinic acid content, and others. The obtained information can help clarify the initial response of chilling injury and is useful to determine the distribution property of tomatoes for avoiding chilling injury-induced cell membrane damage.

Modeling and Visual Simulation of Bifurcation Aneurysms Using Smoothed Particle Hydrodynamics and Murray's Law.

Aneurysm modeling and simulation play an important role in many specialist areas in the field of medicine such as surgical education and training, clinical diagnosis and prediction, and treatment planning. Despite the considerable effort invested in developing computational fluid dynamics so far, visual simulation of blood flow dynamics in aneurysms, especially the under-explored aspect of bifurcation aneurysms, remains a challenging issue. To alleviate the situation, this study introduces a novel Smoothed Particle Hydrodynamics (SPH)-based method to model and visually simulate blood flow, bifurcation progression, and fluid-structure interaction. Firstly, this research consider blood in a vessel as a kind of incompressible fluid and model its flow dynamics using SPH; and secondly, to simulate bifurcation aneurysms at different progression stages including formation, growth, and rupture, this research models fluid particles by using aneurysm growth mechanism simulation in combination with vascular geometry simulation. The geometry incorporates an adjustable bifurcation structure based on Murray's Law, and considers the interaction between blood flow, tissue fluid, and arterial wall resistance. Finally, this research discretizes the computation of wall shear stress using SPH and visualizes it in a novel particle-based representation. To examine the feasibility and validity of the proposed method, this research designed a series of numerical experiments and validation scenarios under varying test conditions and parameters. The experimental results based on numerical simulations demonstrate the effectiveness and efficiency of proposed method in modeling and simulating bifurcation aneurysm formation and growth. In addition, the results also indicate the feasibility of the proposed wall shear stress simulation and visualization scheme, which enriches the means of blood analysis.

Insights into the carbonate/bicarbonate ion-induced failure mechanism of bentonite in drilling fluids

During deep oil and gas drilling, drilling fluids are often polluted with carbon dioxide (CO2). The intrusion of CO2 can affect bentonite performance, leading to deterioration or even failure of drilling fluids. To further investigate the influence of CO2 pollution on the bentonite and its failure mechanism, Na2CO3 simulation experiments were conducted. Performance evaluation showed that as the concentration of HCO3− and CO32− increased, the viscosity, filtration loss, and mud cake permeability of drilling fluids significantly increased. Meanwhile, the drilling fluid foaming was particularly evident. Mechanism studies indicated that the adsorption of HCO3− and CO32− on the bentonite diminished the electrostatic interactions and interlayer spacing between particles, leading to the particles aggregation and a decrease in Zeta potential, ultimately causing the hydration film on the bentonite to become thinner. Simultaneously, this also led to a decline in the dispersibility of bentonite. This study can offer a new research thread for the failure mechanism of bentonite under CO2 pollution and indicate the direction for the study of drilling fluid resistance to acidic gas pollution.

Contributions Regarding the Study of Pulsatility and Resistivity Indices of Uterine Arteries in Term Pregnancies-A Prospective Study in Bucharest, Romania.

Pregnancy is a complex stage in a woman's life, considering the physical and psychological changes that occur. The introduction of Doppler studies of the pregnant woman's vessels and those of the fetus has proven to be a useful tool in evaluating the maternal-fetal relationship. Objective: The study aims to assess the correlations of PI and RI values in term pregnancies. Methods: This analysis is based on the prospective evaluation of medical data from 60 patients who were admitted to the Obstetrics and Gynecology department of Saint Pantelimon Hospital in Bucharest, Romania, from May to August 2024. Among the examined parameters are patient age, blood pressure, amniotic fluid quantity, placenta location, and pulsatility and resistivity indices of uterine arteries. Results: A higher diastolic blood pressure is associated with higher mean PI and RI values, indicating that diastolic blood pressure has a significant correlation to these values. The mean RI shows a moderately negative and significant correlation, suggesting that a lower level of amniotic fluid is associated with a higher mean RI. Regarding the PI value of the uterine arteries, the p-value suggests that the difference between the groups with and without associated diseases is statistically significant. Placental insertion on the anterior or posterior uterine wall does not have a significant impact on the PI and RI values of the uterine arteries, but the values are higher in the contralateral part of the placental insertion. Conclusions: These results strengthen the evidence previously demonstrated. Uterine artery Doppler ultrasonography is an extremely useful tool in monitoring and managing high-risk pregnancies.

Numerical Simulation of the Horizontal Water-Entry Process of High-Speed Vehicles

Based on the RNG k-ε turbulence model and VOF multiphase flow model, a numerical model of horizontal water-entry of the vehicle was established, and the numerical method was verified by experimental results. The cavitation characteristics, fluid resistance, and motion of the vehicle under different conditions were studied during the vehicle’s water-entry process. The results show that the cavitation process can be divided into the cavity development stage, saturation stage, and collapse stage. With the increase in initial velocity and mass of the vehicle, more water vapor will be generated during the water-entry process. The initial velocity of the vehicle had a limited effect on the resistance coefficient. The resistance coefficient in the stable stage remained almost unchanged for vehicles with different masses. Nevertheless, the time interval of the stable stage was shortened, and the resistance coefficient was greater in the gradually increasing stage for the vehicle with a smaller mass. For vehicles with higher initial velocity or smaller mass, the instantaneous velocity decreased faster after it entered the water. The vehicle with a streamlined design was able to reduce the generation of water vapor and decrease fluid resistance and its coefficient, and the vehicle can run farther during the water-entry process.

Influence of habituation on pseudo-haptic weight perception of virtual objects

As the demand for realistic sensations in virtual reality (VR) environments escalates, interfaces that exploit cross-modal interactions between vision and haptics are gaining prominence. Pseudo-haptics, offering a tactile illusion without mechanical feedback devices, has emerged as a viable solution to enhance user immersion by simulating various sensations such as texture, fluid resistance, and weight. However, a potential issue in the long-term effectiveness of these illusions, particularly habituation, where the illusion diminishes after prolonged exposure, remains a concern. This study investigates whether habituation to pseudo-haptic weight illusions occurs with extended use. We conducted quantitative measurements of pseudo-haptic weight perception before and after prolonged exposure. The findings indicate a diminishing effect of pseudo-haptic weight illusion with repeated exposure, particularly among participants with high accuracy in weight perception. This study contributes important insights into the design of VR experiences, highlighting the need to consider the habituation effects when implementing pseudo-haptic illusions for weight perception.

Transient Dynamics of a Porous Sphere in a Linear Fluid

This article describes the unsteady translational motion of a porous sphere with slip-surface in a quiescent viscous fluid. Apart from its radius a and density ρs , the particle is characterized by its permeability parameter γ , slip-length l and effective viscosity-ratio ϵ for interior flow. The Reynolds number for the system is assumed to be small leading to negligible convective contribution, though the transient inertia for both the liquid and the solid is comparable to viscous forces. The resulting linearized but unsteady flow-equations for both inside and outside the porous domain are solved in time-invariant frequency domain by satisfying appropriate boundary conditions. The analysis ultimately renders frequency-dependent hydrodynamic friction for the suspended body. The frictional coefficient is computed under both low and high frequency limit for different values of γ, l and ϵ so that the findings can be compared to known results with impermeable surface. Moreover, the parametric exploration shows that the sphere acts like a no-slip body even with non-zero l if aγ ≫ 1/√ϵ . Scaling arguments from a novel boundary layer theory for flow inside porous media near interfaces explain this rather unexpected observation. Also, computed fluid resistance is incorporated in equation of motion for the particle to determine its time-dependent velocity response to a force impulse. This transient response shows wide variability with ρs, γ, l and ϵ insinuating the significance of the presented study. Consequently, the paper concludes that slip and permeability should be viewed as crucial features of submicron particles if unexpected variability is to be explained in nano-scale phenomena like nano-fluidic heat conduction or viral transmission. Thus, the theory and findings in this paper will be immensely useful in modeling of nano-particle dynamics.

Enhanced drag reduction of superhydrophobic coatings with femtosecond laser processing and TEOS/KH-SiO2/SA hybridization: CFD simulation and particle image velocimetry

Superhydrophobic surfaces have gained significant attention due to their potential applications in reducing frictional drag in various fluid flow systems. These surfaces mimic the lotus leaf's natural water-repellent properties, resulting in minimal contact between water droplets and the surface. The F-L@TEOS/KH-SiO2/SA coatings are developed using a combination of femtosecond laser ablation and chemical modification with tetraethyl orthosilicate (TEOS), KH550-modified SiO2 (KH-SiO2), and stearic acid (SA). The micro-nano structures formed on the surface enhanced its hydrophobicity, with a contact angle (CA) of 165.94°and sliding angle (SA) of 2.35°. The drag reduction performance is evaluated through experimental methods, including particle image velocimetry and gravity-driven motion analysis, as well as numerical simulations using computational fluid dynamics (CFD). Results showed that the superhydrophobic surface significantly reduced drag compared to untreated aluminum, with an average drag reduction ratio of 10.4 % in experiments and a calculated reduction rate of 9.86 % in simulations. The presence of micro-nano structures promoted the formation of an air layer at the solid-liquid interface, decreasing friction and enhancing slip flow. Additionally, the biomimetic surface generated turbulence at specific distances, aiding in energy dissipation and further reducing resistance. These findings demonstrate the potential of superhydrophobic coatings for applications requiring reduced fluid resistance, such as in marine vessels, pipelines, and fluid transport systems.

Intelligent neuron based interpretation of carreau trihybrid nanofluid model with streamline analysis: Configuration of distinct geometries

This current attempt develops a more efficient predictive model that can accurately simulate the behavior of Carreau trihybrid nanofluids in non-trivial configurations. This study interprets thermal behavior of Carreau trihybrid nanofluid model with streamline analysis considering the two geometries wedge and cone. Three nanoparticles are involved in base fluid (water) with physical effects of non-uniform heat sink source and nonlinear thermal radiation are assumed for heat transport and Lorentz forces are considered for velocity inspection. Furthermore, this study employs intelligent neural networks to interpret data for streamline and thermal transport analysis, focusing on the specific cases of wedge and cone geometries. Initial data fetched through bvp4c and further, obtained data trained through supervised neural scheme, Levenberg marquardt neural network (LM-NN) is applied and required predictions are made. Higher “Gc” indicates stronger solutal buoyancy forces, which promote upward fluid movement, thereby increasing the velocity gradient. With increasing (M), the velocity profile decreases. Fluid exhibits enhancing the velocity gradient with higher (n). Higher particle concentration enhances the fluid's viscosity and resistance.

Mechano-synthesized wollastonite-forsterite composite coatings on the plasma electrolytic oxidized Ti-6Al-4V alloy for dental implant

This study investigated an innovative approach for dental implant coatings by developing mechano-synthesized wollastonite-forsterite composite coatings (MC) on plasma electrolytic oxidized (PEO) Ti-6Al-4V alloy. The process involved PEO treatment using a pulsed DC power supply in an electrolyte solution of mono-calcium acetate and calcium glycerophosphate, followed by MC with mixed wollastonite (CaSiO3) and forsterite (Mg2SiO4) powders. After MC treatment, FESEM, EDS analysis, cross-section, XPS, Raman analysis, corrosion test, and an in vitro test for biocompatibility were performed. Comprehensive surface characterization revealed that wollastonite particles transformed into smaller needle-like shapes, while forsterite particles became slightly less uniform but retained their spherical shape. Higher wollastonite content resulted in greater pore filling with fine particles, whereas increased forsterite content led to fewer fine particles on the surface. Cross-sectional analysis showed Si concentration inside the pores. Notably, wollastonite-rich samples exhibited superior corrosion resistance and rapid initial apatite formation in simulated body fluid (SBF) studies. In contrast, forsterite-containing samples demonstrated more controlled and sustained bioactivity, forming magnesium-substituted hydroxyapatite over time. The novelty of this work lies in combining the bioactive properties of wollastonite and forsterite with enhanced PEO surface characteristics, resulting in coatings with tailored corrosion resistance and bioactivity profiles suitable for dental implant applications.

Investigation and In Vitro Studies of a ZrO2/g‐C3N4 Composite Coated on 316L Stainless Steel for Biomedical Applications

ABSTRACTThe advancement of smart coatings for bioimplants has yielded a combination of biocompatibility and corrosion resistance. 316L stainless steel (316LSS) is a commonly used commercial implant, but it has limitations in biocompatibility and durability, which hinders the widespread utilization of 316LSS alloys. In this study, the 316LSS alloy is coated with a mixture of zirconium dioxide (ZrO2), prepared using the sol–gel method, and graphitic carbon nitride (g‐C3N4), synthesized by thermal polymerization. XRD and Raman analyses confirmed the crystal structure and purity of the synthesized samples. The corrosion resistance property was assessed using OCP, POL, and PEIS. The findings demonstrate that the ZrO2/g‐C3N4‐coated 316LSS shows significantly enhanced corrosion resistance and biocompatibility in a simulated body fluid. The in vitro bioactivity test reveals that the ZrO2/g‐C3N4 coating leads to the formation of an apatite layer over the surface of 316LSS. The elemental composition of the HAP deposition was confirmed by Raman analysis. The results suggested that the ZrO2/g‐C3N4–coated 316LSS substrate is a promising material for use in biomedical applications.

A bio-inspired liquid-like smooth copolymer coating with superior biofouling resistance and drag reduction

The marine biofouling and fluid resistance have a detrimental impact on underwater vehicles. It is essential to develop functional material integrated with both antifouling and drag reduction effects for maritime transportation and navigation. Herein, to avoid the disadvantages of common slippery liquid-infused surfaces, such as the complexity of preparation micro/nanopores and the depletion of the lubricant layer, the novel liquid-like coating was fabricated by integrating the synthesized long chain organosilicon monomer (HPSM) to the self-polishing polymer chains. It is that the ingenious design integrated anti-fouling and drag reduction functions. The surface composition and structure, mechanical properties, antifouling and drag reduction properties of the coating were characterized by FT-IR, XPS, SEM, μ-PIV. These results indicated that the unique monomer HPSM endowed the coating with unique liquid-like properties, including special wettability, viscoelasticity and extremely low roughness. The flexibility of HPSM promoted the self-adaption ability of the coating in the seawater environment, which can effectively either reduce the fluid resistance when the fluid flowed through the surface or the adhesion strength of the biofouling, such as lots of protein (BSA) and alga (Porphyridium sp.and Navicula sp.). Moreover, the synergistic effect between liquid-like properties and the interface renewal behavior of self-polishing components further strengthened the antifouling performance of the coating. The marine field test further indicated the comprehensive anti-fouling performance and mechanical stability of the coating in practical application scenarios. This research provided a facile approach for preparing antifouling and drag-reduction coating. Therefore, it was believed to be a great inspiration for the design of functional coating against biofouling and drag reduction in the ship and marine industry field.

Research on temperature distribution characteristics of oil‐immersed power transformers based on fluid network decoupling

AbstractDue to the complex structure and large size of large‐capacity oil‐immersed power transformers, it is difficult to predict the winding temperature distribution directly by numerical analysis. A 180 MVA, 220 kV oil‐immersed self‐cooling power transformer is used as the research object. The authors decouple the internal fluid domain of the power transformer into four regions: high voltage windings, medium voltage windings, low voltage windings, and radiators through fluid networks and establish the 3D fluid‐temperature field numerical analysis model of the four regions, respectively. The results of the fluid network model are used as the inlet boundary conditions for the 3D fluid‐temperature numerical analysis model. In turn, the fluid resistance of the fluid network model is corrected according to the results of the 3D fluid‐temperature field numerical analysis model. The prediction of the temperature distribution of windings is realised by the coupling calculation between the fluid network model and the 3D fluid‐temperature field numerical analysis model. Based on this, the effect of the loading method of the heat source is also investigated using the proposed method. The hotspot temperatures of the high‐voltage, medium‐voltage, and low‐voltage windings are 89.43, 86.33, and 80.96°C, respectively. Finally, an experimental platform is built to verify the results. The maximum relative error between calculated and measured values is 4.42%, which meets the engineering accuracy requirement.

The Carrying Behavior of Water-Based Fracturing Fluid in Shale Reservoir Fractures and Molecular Dynamics of Sand-Carrying Mechanism

Water-based fracturing fluid has recently garnered increasing attention as an alternative oilfield working fluid for propagating reservoir fractures and transporting sand. However, the low temperature resistance and stability of water-based fracturing fluid is a significant limitation, restricting the fracture propagation and gravel transport. To effectively ameliorate the temperature resistance and sand-carrying capacity, a modified cross-linker with properties adaptable to varying reservoir conditions and functional groups was synthesized and chemically characterized. Meanwhile, a multifunctional collaborative progressive evaluation device was developed to investigate the rheology and sand-carrying capacity of fracturing fluid. Utilizing molecular dynamics simulations, the thickening mechanism of the modified cross-linker and the sand-carrying mechanism of the fracturing fluid were elucidated. Results indicate that the designed cross-linker provided a high viscosity stability of 130 mPa·s and an excellent sand-carrying capacity of 15 cm2 at 0.3 wt% cross-linker content. Additionally, increasing reservoir pressure exhibited enhanced thickening and sand-carrying capacities. However, a significant inverse relationship was observed between reservoir temperature and sand-carrying capacity, attributed to changes in the drag coefficient and thickener adsorption. These results verified the effectiveness of the cross-linker in enhancing fluid viscosity and sand-carrying capacity as a modified cross-linker for water-based fracturing fluid.

Viscosity of deep eutectic solvents: Predictive modeling with experimental validation

Viscosity, the measure of a fluid's resistance to deformation, is a critical parameter in many industries. Being able to accurately predict viscosity is essential for the successful design and optimization of technological processes. In this research, regression models were created to predict the viscosity of deep eutectic solvents (DESs). Machine learning models were trained using a data set of 3440 data points for two component DESs. Different algorithms, such as Multiple Linear Regression, Random Forest, CatBoost, and Transformer CNF, were employed alongside a variety of structural representations like fingerprints, σ-profiles, and molecular descriptors. The effectiveness of the models was assessed for interpolation tasks within the training data and extrapolation outside of it. The results indicate that a rigorous splitting of the dataset into subsets is necessary to accurately evaluate the performance of the models. Two new choline chloride-based DESs were prepared and their viscosities were measured to evaluate the predictive capabilities of the models. The CatBoost algorithm with CDK molecular descriptors was chosen as the recommended model. The average absolute relative deviations (AARD) of this model exhibited fluctuations during 5-fold cross-validation, ranging from 10.8 % when interpolating within the dataset to 88 % when extrapolating to new mixture components. The open access model was presented in this study (http://chem-predictor.isc-ras.ru/ionic/des/).