non-Newtonian Fluid Properties Research Articles

Exploring biosynthesis strategies to boost the yield of exopolysaccharide-protein blend from Bacillus arachidis SY8(T), an isolated native strain, as a potent adsorbent for heavy metals removal

This investigation centers on the synthesis of a polysaccharide-protein blend produced by an isolated native strain (99.12 % phylogenetic affinity with Bacillus arachidis SY8(T)). The primary objective was to investigate the production of extracellular polymeric substances (EPS) under diverse stress conditions, encompassing exposure to heavy metal ions, salt, and toxic agents. Additionally, the impact of environmental parameters, namely pH, inoculation percentage, and time, on the production was investigated. Subsequently, the study examined the biosorption potential of the EPS produced for Pb(II), Cu(II), and Mn(II). The EPS obtained was thoroughly characterized via various tests. Rheological evaluations of an EPS solution (2 wt%) confirmed its pseudo-plastic and non-Newtonian fluid properties, while TGA analysis demonstrated its thermal stability up to 600 °C. Additional analyses, including GPC, FTIR, and H-NMR, provide further insights into the produced EPS. The best conditions for EPS production are determined: 5 % NaCl salt, serving as an effective stress inducer, and 37 °C, pH 6, with a 5 % inoculation, over 96 h. EPS demonstrates remarkable removal efficiencies of 99.9, 99.4 and 78.9 % for Pb(II), Cu(II), and Mn(II), respectively. These findings highlight the potential of EPS as an effective agent for removing heavy metal ions.

Analysis of heat and fluid flow for peristaltic wave phenomenon in sisko fluid with temperature-dependent viscosity

Peristaltic flow of Sisko fluid with temperature-dependent viscosity and viscous dissipation is considered in this paper. The constitutive equations for viscous and non-Newtonian power-law fluids are generalized to Sisko fluid. The governing equations take the form of two coupled nonlinear partial differential equations. The analytic solution is calculated using long wavelength and small Reynolds number approximations. The Sisko fluid, being the blend of viscous and non-Newtonian fluids, includes all the rheological properties of non-Newtonian fluid and viscous fluid. The effects of variable viscosity parameter translate into two independent parameters giving rise to two cases. The one corresponding to low shear rate and the other corresponding to infinite shear rate. This is a new approach to look up the effects of fluid properties characterizing Sisko fluid. The paper is essentially a theoretical work with applications in science and technology including biotechnology. In the absence of any empirical data; the results for the viscous and power-law fluids with variable viscosity are deduced from the generalized solution of Sisko fluid presented in this study.

Development and Evaluation of a Novel Antibacterial Wound Dressing: A Powder Preparation Based on Cross-Linked Pullulan with Polyhexamethylene Biguanide for Hydrogel-Transition in Advanced Wound Management and Infection Control.

As antibiotic resistance increasingly undermines traditional infection management strategies, there is a critical demand for innovative wound care solutions that address these emerging challenges. This study introduces a novel antibacterial wound dressing based on Cross-Linked Pullulan (Pul) and Polyhexamethylene Biguanide (PHMB) for enhanced wound management and infection control. The dressing's adsorption rate reached 200% of its original weight within 30 min, exceeded 300% after 5 h, and exhibited significant non-Newtonian fluid properties. The dressings were able to release the loaded medication completely within 20 min; additionally, the dressing demonstrated significant antibacterial activity against a broad spectrum of bacteria. Significantly, the therapeutic effects of the Pul-PHMB/GP dressing were evaluated in a mouse model. Compared to untreated wounds, wounds treated with Pul-PHMB/GP exhibited a significant gelation process within 5 min post-treatment and showed a significant increase in wound healing rate within 12 days. This powder preparation overcomes the limitations associated with liquid and gel dressings, notably in storage and precise application, preventing the premature expansion or dissolution often caused by PHMB in high-humidity environments. The powder form can transform into a gel upon contact with wound exudate, ensuring accurate coverage of irregular wounds, such as those from burns or pressure sores, and offers excellent chemical and physical stability in a dry state, which facilitates storage and transport. This makes the dressing particularly suitable for emergency medical care and precision therapy, significantly improving the efficiency and adaptability of wound treatment and providing robust support for clinical treatments and emergency responses.

Effects of Rheological Properties of Non-Newtonian Middle Fluids on the Formation Dynamics of Double Emulsions in Coflowing Microfluidic Emulsification

Effects of Rheological Properties of Non-Newtonian Middle Fluids on the Formation Dynamics of Double Emulsions in Coflowing Microfluidic Emulsification

Numerical investigation of double emulsion formation in non-Newtonian fluids using double co-flow geometry

This paper uses the Volume of Fluid (VOF) method to simulate a double Co-Flow microfluidic device that can produce double emulsions in both Newtonian (water) and non-Newtonian fluids. The simulation is 2D axisymmetric and involves three phases. A model is evaluated in this study to examine how the size and double emulsion’s generation rate are impacted by factors such as phase velocity, viscosities, interfacial tension, and the rheological properties of non-Newtonian fluids. The model predicted the process of emulsification successfully in dripping and jetting regimes and predicted the impacts of phase velocity on the dimension and frequency of compound droplets. Increasing the flow rate of the inner phase causes the inner droplets to grow, while the outer droplet dimensions remain mostly unchanged. Vice versa, an increase in outer phase flow rate reduces compound droplet size. However, when the middle phase's flow rate is enhanced, the size of detached droplets in the inner and outer phases undergoes opposite changes, i.e., decreasing and increasing, respectively. The results showed that in non-Newtonian fluids, smaller droplets are formed compared to water, and the diameter of the double emulsions formed decreases with the rise in the viscosity at zero shear rate of the non-Newtonian fluid.

Ion current rectification properties of non-Newtonian fluids in conical nanochannels.

Ionic current rectification generated by the geometric asymmetry of conical nanochannels has gradually attracted attention, but most studies have been limited to Newtonian fluids. In this study, the ionic current rectification characteristics in conical nanochannels filled with non-Newtonian fluids are investigated by numerical simulations. Electroosmotic flow and ion transport in Sisko fluids are solved using the Poisson-Nernst-Planck equations and the Navier-Stokes equations. The effects of the Debye parameter, power-law indexes and applied voltage on the ionic current, axial potential, ion concentration, radial velocity and rectification ratio in the nanopores are investigated. When κRt = 1, the current rectification ratio increases with the increase of the power-law index. However, when κRt = 6, the current rectification ratio first increases and then decreases with the increase of the power law index, reaching the maximum value at n = 1.0. These findings have positive implications for the construction of some nanodevices such as nanofluidic diodes.

Influence of Hazelnut and Walnut Oil Cakes Powder on Thermal and Rheological Properties of Wheat Flour.

The aim of the study was to assess the influence of the addition of powdery hazelnut oil cakes (HOC) or walnut oil cakes (WOC) to wheat flour (WF) on its selected thermal and rheological properties. In the research material, part of the wheat flour (5%, 10%, 15%) was substituted with powdery oil cakes based on hazelnuts and walnuts. The control sample was wheat flour (100% WF). In the tested systems with the addition of hazelnut oil cakes (WFHOC) and walnuts (WFWOC), the characteristics of the gelatinization and retrogradation processes were determined using the DSC method, the gelatinization characteristics of 10% pastes using the RVA method, flow curves and viscosity curves, as well as mechanical spectra. Based on the results obtained, it was found that the type of oil cakes and the level of their addition significantly influenced the thermal and rheological properties of the tested systems. Partial replacement of wheat flour with HOC or WOC significantly influenced most DSC parameters. The highest values of gelatinization enthalpy ∆HG and retrogradation ∆HR were characteristic of the WFWOC5% sample (5.9 J/g) and the control sample (1.3 J/g), respectively. All tested systems showed the properties of shear-thinning non-Newtonian fluids, and the partial replacement of wheat flour with HOC or WOC resulted in a significant reduction in the maximum viscosity of pastes, increasing with the increase in the proportion of oil cakes. WFHOC-based pastes were characterized by higher values of the G' and G″ modulus, while their values and the values of the K' and K″ parameters decreased as the share of oil cakes increased. Gels based on all tested systems showed the nature of weak gels (tan δ = G″/G' > 0.1). Replacing part of the wheat flour with nut oil cakes modified the thermal and rheological properties of pastes and gels, and the observed changes were influenced by both the origin and the level of addition of powdered oil cakes. It was found that WFHOC/WFWOC15% systems had reduced viscosity and weakened viscoelastic properties compared to systems with a lower OC content, which is not a favorable feature from the technological point of view. However, these systems were the most stable, which is an advantageous feature. However, for baking purposes, research should be carried out on the rheological properties of dough made from these mixtures.

Radiation Absorption on Non- Newtonian Fluid over A Vertical Plate with Radiation Heat Flux

The study of radiation absorption in non-Newtonian fluids flowing over a vertical plate subjected to radiation heat flux is a complex yet critical area of research that finds wide applications in engineering, physics, and environmental sciences. In this investigation, we explore the intricate interplay between radiation heat transfer, the unique rheological properties of non-Newtonian fluids, and the resulting fluid dynamics and heat transfer phenomena. Non-Newtonian fluids, characterized by their nonlinear relationship between shear stress and shear rate, exhibit behavior that deviates from traditional Newtonian fluids. This departure introduces complexity into the heat transfer process when subjected to radiation heat flux. The vertical plate, a common boundary encountered in practical engineering scenarios, serves as a platform for examining these interactions. Research in this field employs a multidisciplinary approach, encompassing experimental investigations, mathematical modeling, and computational simulations. These methodologies are instrumental in unraveling the complexities of radiation absorption in non-Newtonian fluids over vertical plates and provide a foundation for advancements in various engineering and scientific domains.
 Keywords: Radiation, Absorption, Transfer, Modeling, non-Newtonian

Biomechanics of abdominal aortic aneurysm in the framework of Windkessel effect and fully-developed inflow velocity via two-way non-linear FSI

Abdominal aortic aneurysm (AAA) is a pathological condition characterised by localised dilation of the infrarenal aorta, which can be fatal if rupture occurs. Current diagnostic criteria for repair are not patient-specific, but computational modelling may help to predict the potential growth and risk of AAA rupture accurately. This paper highlights how important using the Windkessel effect and fully-developed inflow velocity framework for the biomechanical analysis of AAA is; in other words, this research investigates how different boundary conditions in modelling methods affect the ability to correctly represent the biomechanics of AAA with complex non-linear parameters using a two-way fluid–structure interaction (FSI) technique. Time-averaged wall shear stress (TAWSS) is highly sensitive to boundary conditions, so unrealistic or simplified boundary conditions can lead to very different TAWSS results. This study also revealed that the use of outflow 3-element Windkessel boundary conditions on pulsatile pressure affects the flow pattern and increases the flow recirculation period. By accounting for the Windkessel effect and preventing backflow in numerical studies of AAA, the maximum displacement found in the distal branches can also be reduced. Models assuming plug velocity profiles overestimate peak wall stress by approximately 20% compared with models using fully developed parabolic inlet velocity profiles. This study incorporated a three-layer anisotropic material model and non-Newtonian fluid properties into the simulation, providing a more realistic representation of the effect of boundary condition selection on AAA mechanics. The results summarised from the parametric study could contribute to better prediction of AAA growth and rupture risk, and have important implications for the development of improved treatment strategies for AAA patients.

Variable viscosity effects on unsteady MHD reactive third-grade fluid with asymmetric convective cooling within porous Couette device

The principal motive of this study is to present a detailed account of the impact of both flow and energy profile of a time-dependent, incompressible, reactive third-grade fluid having low electrical conductivity besides variable viscosity through a porous channel accompanied by asymmetric cooling at the walls. The highly coupled equation of motion and energy manifested as non-linear partial differential equations are represented as algebraic equations using an implicit finite difference scheme and solved numerically by implementing the damped-Newton method. The solution obtained is eventually simulated using MATLAB and the resulting graphs representing the influence of non-dimensional parameters on the flow field and temperature field are discussed thoroughly. It is noted that an increase in γ values enhances non-Newtonian fluid properties which result in the thickening of the fluid and consequently fall in fluid velocity. An increase in reaction parameter and variable viscosity values remarkably enhances viscous heating source terms and contributes to the overall rise in fluid temperature. It is also observed that due to the nature of coupling of the source terms, for the majority of the non-dimensional parameters, there is a simultaneous increase or decrease in the momentum and energy profile of the fluid.

Navigation and Control of Motion Modes with Soft Microrobots at Low Reynolds Numbers.

This study investigates the motion characteristics of soft alginate microrobots in complex fluidic environments utilizing wireless magnetic fields for actuation. The aim is to explore the diverse motion modes that arise due to shear forces in viscoelastic fluids by employing snowman-shaped microrobots. Polyacrylamide (PAA), a water-soluble polymer, is used to create a dynamic environment with non-Newtonian fluid properties. Microrobots are fabricated via an extrusion-based microcentrifugal droplet method, successfully demonstrating the feasibility of both wiggling and tumbling motions. Specifically, the wiggling motion primarily results from the interplay between the viscoelastic fluid environment and the microrobots' non-uniform magnetization. Furthermore, it is discovered that the viscoelasticity properties of the fluid influence the motion behavior of the microrobots, leading to non-uniform behavior in complex environments for microrobot swarms. Through velocity analysis, valuable insights into the relationship between applied magnetic fields and motion characteristics are obtained, facilitating a more realistic understanding of surface locomotion for targeted drug delivery purposes while accounting for swarm dynamics and non-uniform behavior.

Tracer dispersion due to non-Newtonian fluid flows in hydraulic fractures with different geometries and porous walls

Tracer transport in hydraulic fractures is substantially affected by the rock matrix surrounding them. Nevertheless, there is not yet an expression in literature to address the relationship among the transport coefficients, porous walls, hydraulic fracture geometries, and non-Newtonian fluid properties. Therefore, the tracer dispersion due to non-Newtonian fluid flows in hydraulic fractures with different geometries and porous walls is mathematically derived and studied in the current work. Rectangular, triangular, and elliptical models and power-law model are considered here to describe the hydraulic fracture geometry and the non-Newtonian fluid rheology, respectively. The results reveal that as the flow behavior index grows, the coefficient of the shear dispersion term in the case of the shear thinning and Newtonian fluids follows an order of triangular > elliptical > rectangular and in the case of the shear thickening while the same order is followed at the beginning, it turns first to triangular > rectangular > elliptical, then to rectangular > triangular > elliptical, and finally to rectangular > elliptical > triangular. The coefficient of the shear dispersion term increases sharply for each geometrical model with the flow behavior index when the fluid is shear thinning while it first increases slightly and then flattens when the fluid is shear thickening. However, the coefficient of the shear dispersion term for porous walls is lower than the one for nonporous walls. It is also found that the average tracer dispersion coefficients in rectangular, triangular, and elliptical nonporous-walled and porous-walled hydraulic fractures and their ratio dictate that the hydraulic fracture-rock matrix communication through the continuity of the tracer concentration and the mass flux needs to be considered for determination of the tracer dispersion during the transition for intermediate Peclet numbers and the advection-dominated tracer transport for large Peclet numbers. This study along with its findings can pave the way for future investigations on the tracer dispersion in a network of hydraulic fractures with rough and porous walls.

Interactions between Fuzi (Aconiti Lateralis Radix Preparata) total alkaloids and Fuzi starch: Structural, physicochemical, and rheological properties

Interactions between starch and nonstarch components have attracted enormous attention, but limited information is available on the interactions between starch and alkaloids. To elucidate the interaction mechanism between Fuzi total alkaloids (FTA) and Fuzi starch, Fuzi starch-FTA complexes with different FTA concentrations (0, 1, 3, and 5 g/100 g Fuzi starch) were prepared, and their structural characteristics, physicochemical properties, and rheological behaviors were investigated. Fourier transform infrared spectroscopy results demonstrated that FTA interact with starch via hydrogen bonding. Moreover, the addition of FTA increased the formation of a short-range ordered structure. X-ray diffraction results confirmed the existence of hydrogen bonding and suggested that the relative crystallinity of Fuzi starch decreases with the presence of FTA. Furthermore, FTA elevated the solubility of Fuzi starch and reduced its swelling power, coagulability, gelatinization temperature, and enthalpy change. Based on rheological analyses, Fuzi starch-FTA complexes exhibited non-Newtonian fluid properties and a typically weak gel rheological behavior. After adding FTA, the shear stress, viscosity, and storage/loss modulus of Fuzi starch decreased. Overall, our work enriches the theory of starch-alkaloid interactions and provides data to support investigation into the future applications of Fuzi starch.

Casson Nanofluid Instability with Viscosity and Conductivity Variation Using Brinkman Model

The present work investigates the onset of convective instability of a non-Newtonian Casson nanofluid layer saturating a porous medium. Conductivity and viscosity are taken to be linear functions of nanoparticle volume fraction and Darcy-Brinkman model is used to modify the momentum equation. It is assumed that all the physical variables undergo a small disturbance on the basic solution and the normal mode technique is used to convert partial differential equations into ODE’s to get the expression of thermal Rayleigh number. Darcy parameter, non-Newtonian fluid property and conductivity variation parameter are coupled together leading to a significant increase in the stability of the layer. Numerical computations are carried out for various base fluids (water, oil, blood, glycol) under different porous phases (glass wool, limestone, sand) for metallic and non-metallic nanoparticles (copper, Iron, alumina, silicon oxide) using the software Wolfram Mathematica (version 12.0). The novelty of the work lies in the fact that the conductivity variation pattern for porous media is established as glass wool < limestone < sand and for base fluids as water < blood < glycol < oil. Maximum conductivity variation is observed for copper-oil nanofluid with sand as porous medium and glass saturated with alumina-water nanofluid shows the minimum variation. Oscillatory mode is found to dominate the instability state for bottom-heavy fluid layer. Darcy parameter stabilizes the fluid layer while porosity effects are destabilizing. Metals are found to be more stable as compare to non-metals.

Experimental Study on a Liquid-Solid Phase-Change Autogenous Proppant Fracturing Fluid System.

In this paper, a liquid-solid phase-change autogenous proppant fracturing fluid system (LSPCAP) was proposed to solve the problems that was caused by "sand-carrying" in conventional fracturing technology in oil and gas fields. The characteristic of the new fluid system is that no solid particles will be injected in the whole process of fracturing construction except liquids. The fluid itself will transform into solid particles under the formation temperature to resist the closure stress in the fractures. There are two kinds of liquids that make up the new fracturing fluid system. One of the liquids is called phase-change liquid (PCL) which occurs in the liquid-solid phase change under the formation temperature to form solid particles. Another is called nonphase-change liquid (NPCL) which controls the dispersity and size of PCL in the two-phase fluid system. Based on the molecular interaction theory and organic chemistry, bisphenol-A epoxy resin was selected as the building unit of the PCL, and the NPCL consisted of deionized water + nonionic surfactant. The test results indicated that the new fracturing fluid shows the properties of non-Newtonian fluid and has no wall-building property. The new fluid system has good compatibility with the formation fluid, conventional fracturing fluid, and hydrochloric acid. Through the filtration test, the filtration coefficients of PCL, NPCL, and mixture are found to be 1.56 × 10-4 m/s1/2, 2.66 × 10-4 m/s1/2, and 1.7 × 10-4 m/s1/2, respectively, and the damage rate of mixture and NPCL is 18 and 17.7%. The friction test results show that the resistance reduction rate reaches 69% when the volume ratio of PCL and NPCL is 1:10. The shear rate and time only affect the size of the autogenous solid particles, and the sorting coefficient (S) of the particles is 1.04-1.73, indicating good sorting. Crushing resistance and conductivity test results show that the crush rate of autogenous solid particles is 3.56-8.42%. The conductivity of the autogenous solid particles is better than those of quartz sand and ceramsite under a pressure of 10-30 MPa.

Bioconvective Peristaltic Transport of a Nano Eyring-Powell Fluid in a Vertical Asymmetric Channel with Gyrotactic Microorganism

Peristaltic nanofluid’s flow due to the enhanced thermal performances of nanoparticles and their importance in many sectors play a vital role in medicine, cosmetics, manufacturing, and engineering processes. In this regard, the current theoretical work examines the swimming behavior of migratory gyrotactic microorganisms in a non- Newtonian blood-based nanofluid that is subjected to a magnetic field. The addition of motile microorganisms improves heat and mass transmission by stabilizing the nanoparticle suspension created by the combined actions of buoyancy force and magnetic field. This fluid pattern may display both Newtonian and non-Newtonian fluid properties. Continuity, temperature, motile microbe, momentum, and concentration equations are used in the mathematical formulation. The series solutions are found using the perturbation technique, and the leading parameters are described using graphs. Further, the impact of various physical constraints on different physiological quantities is addressed and illustrated through graphs and is pondered in detail. Bioconvection reduces the density of gyrotactic bacteria, according to the findings. Such findings are beneficial to biomedical sciences and engineering. Microorganisms are helpful in the breakdown of organic matter, the production of oxygen, and the maintenance of human health.

Structural evolutionary behavior of Zr-based bulk metallic glasses under thermoplastic deformation

Zr55·7Cu22·4Al14.7Ni7.2 alloy rods with a diameter of 3 mm were prepared by copper mold suction casting. The microstructure, thermomechanical properties and high temperature plastic deformation behavior of the alloy specimens before and after uniaxial compression in supercooled liquid region (SLR) were investigated by X-ray diffractometer, scanning electron microscope, differential scanning calorimeter and microcomputer-controlled electronic universal testing machine. And the effects of different deformation conditions on the thermomechanical properties and microhardness of the specimens after high temperature deformation were analyzed. The results show that during plastic deformation in SLR, this alloy exhibits stress overshoot in the low temperature region - high strain rate conditions, exhibiting non-Newtonian fluid properties, while alloy softening occurs in the high temperature region - medium to high strain rate, showing the deformation behavior of a Newtonian fluid. The alloy crystallizes after deformation at high temperature and low strain rate (750 K, 2 × 10−4 s−1 and 760 K, 2 × 10−4 s−1∼5 × 10−4 s−1), generating dendritic τ3 phase (Zr51Cu28Al21), while still maintaining an amorphous structure in the low and medium temperature region, but this structure has part of the amorphous matrix that has been transformed into ordered clusters of atoms, and the degree of transformation increases sharply with decreasing strain rate, which in turn causes a sharp reduction in the crystallization incubation period and the exothermic enthalpy of crystallization. And the effect of high temperature deformation on the Vickers microhardness of metallic glass was analyzed.

Study of the Wear Resistance of a Friction unit with a Non-Standard Support Profile and a Metal Coating

The theoretical calculations and the results of experiment for a friction unit consisting of a wedge-shaped support surface are presented in this research paper. The slider on the tread surface has a metal alloy. The lubricating fluid is represented by a lubricant with non-Newtonian characteristics; it has the laminar flow in this unit. The friction unit functions when the cavity between the slider and the support ring is completely filled. To solve the theoretical problem under given conditions, the equations of continuity, the rate of mechanical energy dissipation, the values of the expression for the displacement of a non-Newtonian fluid were used. In addition, equations were used to characterize the profile of a slider with a melt on the tread surface. The presented problem was solved by the self-similar variable method with asymptotic expansion in the smallest parameter. Upon calculation, it is given the equations for the first and zero pressure approximations and it is determined the velocity field are determined with and without the molten metal. Further, the friction force and load capacity were found using the non-Newtonian properties of the lubricating fluid and the above structural characteristics of non-standard surfaces for friction contact.

THE EFFECT OF POLYDEXTROSE ON RHEOLOGICAL CHARACTERISTICS AND SENSORY PROPERTIES OF REDUCED SUCROSE STARCH-MILK DESSERTS

Introduction. The aim of the study was to assess the impact of replacing sucrose with polydextrose (E 1200) on the rheological characteristics and sensory properties of starch-milk desserts sweetened with steviol glycosides (E 960). The study materials were desserts made of oxidized potato starch (E 1404), skimmed milk powder, curcumin, vanilla flavorsucrose and/or a mixture of polydextrose (E 1200) and steviol glycosides (E 960). As part of the rheological analyses, the pasting characteristics, viscosity curves and mechanical spectra of the desserts were determined. As part of the sensory analysis, palatability and texture were assessed using a quantitative descriptive analysis. The acceptability of the desserts was also assessed. Results and discussion. Based on the results, it was found that the partial or complete elimination of sucrose from the composition of desserts and replacing it with a mixture of polydextrose and steviol glycosides led to a reduction in their maximum viscosity determined at the heating stage in the pasting test, but did not change the starch pasting temperature. The desserts showed shear-thinning non-Newtonian fluid properties, and the modification of the recipe resulted in a reduction of the consistency coefficient and a reduction in the share of elastic properties without a significant impact on the viscous properties of the system. The desserts in which sucrose was completely, or in a greater degree, replaced with polydextrose and steviol glycosides had a cooling effect and had a licorice aftertaste in the sensory assessment, while retaining sweetness similar to the sweetness of the dessert sweetened with sucrose only. The modification of the dessert recipe did not affect the adhesiveness and mouth melting of the finished products, but contributed to a reduction in their viscosity and malleability assessed by the sensory analysis. Both the texture and palatability of the desserts prepared to the recipe, in which two-third of the amount of sucrose or its total amount was replaced with polydextrose and steviol glycosides, turned out to be less sensorily acceptable than the dessert which did not contain polydextrose.

Study of Thixotropic Characteristics of a Kerosene Gel Propellant by Bayesian Optimization

The rheological behavior of gel propellants is crucial for their practical applications, especially in the rocket engine and ramjet fields. The thixotropic characteristics of gel propellants are an important component of their rheological properties and have a notable impact on their flow and injection process. However, most gel propellants contain rich, dynamic cross-linked network structures, which impart complex non-Newtonian fluid properties, and it is difficult to establish a unified mathematical model. In view of this, this study addresses the thixotropy of a prepared RP-3 kerosene gel and determines the mathematical model and model parameters describing its thixotropy. Experiments show that the kerosene gel exhibits shear-thinning properties as well as thixotropy. To describe the microstructural changes in the gel, three thixotropic constitutive models are introduced to analyze the rheological data, and the constitutive equation parameters are optimized. The three models are all structural dynamic models, which can be used to describe microstructural changes within the material. In addition, the fitting of the constitutive equation is a multiparameter optimization problem, and an appropriate optimization method must be used for parameter fitting. Therefore, the Bayesian optimization method combined with Gaussian process regression and the upper confidence bound (UCB) acquisition function is used in the multiparameter fitting of the constitutive models. Both experiments and numerical results show that the thixotropic model, which introduces a pre-factor with shear strain and assumes that the breakdown of the gel structure is related to energy dissipation rather than the shear rate, has a better fitting effect and prediction ability with regard to the gel. Combined with transient experiments at different shear rates, the model parameters of the constitutive law can be determined quickly by applying the Bayesian optimization method.