Viscoelastic Nature Research Articles

Comparison of the Performance of Nonlinear Time-Dependent Constitutive Models Calibrated with Minimal Test Data Applied to an Epoxy Resin

Epoxy resins are extensively employed as adhesives and matrices in fibre-reinforced composites. As polymers, they possess a viscoelastic nature and are prone to creep and stress relaxation even at room temperature. This phenomenon is also responsible for time-dependent failure or creep fracture due to cumulative strain. Several constitutive equations have been used to describe the mechanical time-dependent response of polymers. These models have been proposed over the past six decades, with minimal direct and practical confrontation. Each model is associated with a specific application or research group. This work assesses the predictive performance of four distinct time-dependent constitutive models based on experimental data. The models were deemed sufficiently straightforward to be readily integrated into practical engineering analyses. A range of loading cases, encompassing constant strain rate, creep, and relaxation tests, were conducted on a commercial epoxy resin. Model parameter calibration was conducted with a minimum data set. The extrapolative predictive capacity of the models was evaluated for creep loading by extending the tests to five decades. The selected rheological models comprise two viscoelastic models based on Volterra-type integrals, as originally proposed by Schapery and Rabotnov; one viscoplastic model, as originally proposed by Norton and Bailey; and the Burger model, in which two springs and two dashpots are combined in a serial and parallel configuration. The number of model parameters does not correlate positively to superior performance, even if it is high. Overall, the models exhibited satisfactory predictive performance, displaying similar outcomes with some relevant differences during the unloading phases.

Operando Gravimetric and Energy Loss Analysis of Na3V2(PO4)2F3 Composite Films by Electrochemical Quartz Microbalance with Dissipation Monitoring.

The rising demand for energy storage calls for technological advancements to address the growing needs. In this context, sodium-ion (Na-ion) batteries have emerged as a potential complementary technology to lithium-ion batteries (Li-ion). Among other materials, Na3V2(PO4)2F3 (NVPF) is a promising cathode for Na-ion batteries due to its high operating voltage and good energy density. In order to further characterize the (dis)charge behavior of NVPF, the electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) was employed to track both the frequency and dissipation loss changes at the electrode/electrolyte interface. The electrode composite preparation proved to be crucial for extending the potential window to both Na3V2(PO4)2F3/Na2V2(PO4)2F3 and Na2V2(PO4)2F3/Na1V2(PO4)2F3 domains. Composites prepared with rawNVPF powder (1-20 μm particles) and polyvinylidene fluoride (PVDF) binder (raw-NVPF:PVDF) exhibited large dissipation changes during (dis)charging, attributed to the soft viscoelastic nature of the binder and substantial hydrodynamic interaction caused by the large particles. On the other hand, composites prepared by sieved NVPF particles (<1 μm particles) with sodium carboxymethyl cellulose (NaCMC) binder (sieved-NVPF:NaCMC) showed rigid properties, enabling an extended and more accurate gravimetric analysis. This allowed for the determination of a linear charge-to-mass relationship for the full potential window of NVPF, reflecting the potential independent insertion/deinsertion of bare Na ions (23 g·mol-1). Additionally, reversible dissipative changes were observed for the Na3V2(PO4)2F3/Na2V2(PO4)2F3 transition, with no further dissipative changes observed during the Na2V2(PO4)2F3/Na1V2(PO4)2F3 process.

INSTABILITY OF THERMOSOLUTAL CONVECTION OF KELVIN-VOIGT FLUID IN A POROUS MEDIUM USING DARCY-BRINKMAN MODEL

In this article, we investigate the problem of thermosolutal convection of a class of viscoelastic fluids in a porous medium of Darcy-Brinkman type. This phenomenon takes place when a layer is heated from beneath while also being exposed to salt either from the upper or lower side. Both linear instability and conditional nonlinear stability analyses are applied in this study. The eigenvalue system have been solved using the Chebyshev collocation technique and the QZ algorithm. The computation of instability boundaries is undertaken for the occurrence of thermosolutal convection in a fluid containing dissolved salt, where the fluid is of a complex viscoelastic nature resembling the Navier-Stokes-Voigt type. Notably, the Kelvin-Voigt parameter emerges as a critical factor in maintaining stability, particularly for oscillatory convection. In instances where the layer is heated from below and salted from above, the thresholds of stability align with those of instability, substantiating the appropriateness of the linear theory in predicting the thresholds for convection initiation. Conversely, when the layer is subjected to salting from the bottom while being heated, the thresholds of stability remain constant even with variations in the salt Rayleigh number. This leads to a significant disparity between the thresholds of linear instability and those of nonlinear stability.

3D printing of TPMS microlattice: indentation characterisation and numerical analysis

ABSTRACT Mechanical metamaterials are emerging as an important tool in many engineering applications, where microarchitectured lattices have advantages of high strength-to-weight ratios, energy absorption capabilities and versatility in designed mechanical behaviours. Whilst a variety of microarchitectured lattices have been previously investigated for their mechanical properties, they have been mostly constrained to strut and plate-based designs and subjected to additional post-processing to modify their functionality. In this work, we demonstrate a novel approach utilising the two-photon polymerisation (2PP) method to generate complex, defect-free microarchitectured lattices. Unlike traditional methods, our technique allows for the direct fabrication of shell-based triply periodic minimal surfaces (TPMS) without requiring any additional post-processing. We utilise gyroid and diamond TPMS unit cells to perform uniaxial micro-compression testing to characterise their mechanical properties. In doing so, we gain insights into the mechanical behaviours of microlattices, with the finding that diamond cells possess superior stiffness and energy absorption potential compared to gyroid cells. To unravel the size-dependency property alterations at this scale, we further analyse a variety of bending beam samples and observed a strain rate-dependent mechanical behaviour attributable to the material's viscoelastic nature. We employ finite element analysis to enhance our understanding of the deformation mechanisms inherent in TPMS topologies, finding good agreement with measured mechanical properties. This work establishes a comprehensive framework that spans from design and geometry characterisation to robust microstructure testing using indentation, combined with comprehensive numerical simulation.

Deciphering Oxidation-Dominated Abnormal Rheology to Design Performance-Stable Liquid-Metal-Based Nanofluids for Transmission Applications.

With global decarbonization urgency for sustainability, enhancing the service stability of liquid metals (LMs) and reducing their oxidation-induced failures are crucial. The oxidation of LMs can adversely affect the fluidity required for hydraulic transmission, thermal management, and other transport scenarios. Given the importance, we have fabricated an LM-based SiC/graphene-Mo nanofluid (LMNF) and compared the rheological behavior to pure LM under an oxidative atmospheric environment. Using an omni-spectrum rotary rheometer and a water bath ultrasonic technique, we quantified a more stable rheological performance in our LMNFs and elucidated how it linked to LMNFs' phase interactions and oxidation. Their temperature-viscosity characteristics are less susceptible to dealloying-accompanied severe oxidation because the nanophase-enabled strong interfacial bonding by SiC, graphene, and Mo gives LMNFs a more viscoelastic solid nature. With these observations, a performance-predicting model, validated through real hydraulic transmission demonstrations, is developed to decipher the relationship among oxidation-influenced rheological performance like viscosity, temperature, and nanophase and guide LMNF design. This model provides a robust framework to fabricate LMNFs for long-term applications with a stable performance.

Does annulus fibrosus lamellar adhesion testing require preconditioning?

The interlamellar matrix (ILM), located between the annular layers of the intervertebral disc, is an adhesive component which acts to resist delamination. Investigating the mechanical properties of the ILM can provide us with valuable information regarding risk of disc injury; however given its viscoelastic nature, it may be necessary to conduct preconditioning on tissue samples before measuring these ILM properties. Therefore, the aim of this study was to optimize mechanical testing protocols of the ILM by examining the effect of preconditioning on stiffness and strength of this adhesive matrix. Eighty-eight annular samples were dissected from twenty-two porcine cervical discs and randomized into one of four testing conditions consisting of 10 cycles of 15% strain followed by a 180° adhesive peel test. The four testing groups employed a different strain rate for the 10 cycles of preconditioning: 0.01 mm/s (n=23); 0.1 mm/s (n=26); 1 mm/s (n=23); no preconditioning employed (n=16). Samples preconditioned at 0.01 mm/s were significantly less stiff than those that had not received preconditioning (p=0.014). No other results were found to be statistically significant. Given the lack of differences observed in this study, preconditioning is likely not necessary prior to conducting a 180° peel test. However, if preconditioning is employed, the findings from this study suggest avoiding preconditioning conducted at very slow rates (i.e. 0.01 mm/s) as the long testing time may negatively affect the tissue.

Analysis of the Creep Curve Reinforced Concrete Beams in Eurocode 2 via the Three-Parameter Model

Creep is characterized by progressive deformation that occurs in concrete structures when exposed to constant loads during their operation. Factors such as air humidity, temperature, the initial consistency of the concrete, and the strength of the concrete after curing are decisive for the advancement of this phenomenon and the resulting deformation over time. In reinforced concrete beams, these deformations can increase the final deflection corresponding to the serviceability limit state, as well as cause the failure of the system at the ultimate limit state. The three-parameter model is suitable for describing the viscoelastic nature of many solids and is frequently used to study the phenomenon in various scientific fields. In this work, the creep model could be considered in two ways: first, the mathematical model for creep predicted by Eurocode 2 (European Standard EN 1992-1-1), and second, a three-parameter viscoelastic model whose parameters are adjusted to match the results obtained with the use of Eurocode. A three-parameter mathematical model was developed to accurately represent the creep curve of Eurocode 2 using computational modeling. In this context, this study seeks to understand the effects of creep in reinforced concrete structures through numerical modeling using a three-parameter model of a simply supported beam designed for usual building loads. A basic literature review on creep in concrete structures was conducted, followed by a structural analysis at different times during the commonly accepted life expectancy of these structural systems. In the simulation, the three-parameter model was used as an alternative to the creep calculation prescribed in Annex B of EUROCODE 2. During the analysis process, curves representing the investigated phenomenon were generated, considering different ambient temperature values, with the results presented in the form of graphs and tables. The adopted structural element was a rectangular reinforced concrete beam, simply supported at the ends. The adopted load was uniformly distributed. With this, it was possible to assess the displacements over time, enabling the evaluation of creep deformations at different stages of time under the influence of temperature and ambient humidity.

Numerical FE Three-phasic Simulation to Predict the Effect of Air Voids on the Dynamic Modulus of Bituminous Composites

In this study, the mechanical performance of bituminous composites was predicted using an upscaling methodology that integrated both finite element analysis and analytical modeling. The FE approach was employed to incorporate intricate geometries and material characteristics. The dynamic modulus of the matrix and the elastic properties of aggregates served as inputs for the numerical models at various scales. This approach considers the distinctive attributes of the granular framework at each level. Furthermore, the investigation involved the influence of air void proportions on the composite's modulus. The numerical models encompassed the random incorporation of air voids within the matrix at varying levels. Notably, it was observed that at low frequencies air voids reduced the dynamic modulus of asphalt more than at high frequencies due to its effect on viscoelastic nature of the bituminous composite. Moreover, heightened temperatures intensified the impact of air void on the dynamic modulus of the asphalt mixture.

Effects of Geometry and Supporting Silicone Layers on the Performance of Conductive Composite High-Deflection Strain Gauges

Piezoresistive sensors composed of nickel nanostrands, nickel-coated carbon fibers, and silicone can be used to measure large physical deflections but exhibit viscoelastic properties and creep, leading to a complex and nonlinear electrical response that is difficult to interpret. This study considers the impact of modifying the geometry and architecture of the sensors on their mechanical and electrical performance. Varying the sensor thickness leads to potentially significant differences in conductive fiber alignment, while adding external layers of pure silicone provides elastic support for the sensors, potentially reducing their extreme viscoelastic nature. The impact of such modifications on both mechanical and electrical behavior was assessed by analyzing strain to failure, the magnitude of hysteresis with cycling, the repeatability of the electro-mechanical response, the strain level at which resistance begins to monotonically decrease, and the drift in electrical response with cycling. The results indicate that thicker single-layer sensors have less electrical drift. Sensors with a multilayered architecture exhibit several improvements in behavior, such as increasing the range of the monotonic region by approximately 52%. These improvements become more significant as the thickness of the pure silicone layers increases.

Singular viscoelastic perturbation to soft lubrication

Soft lubrication has been shown to drastically affect the mobility of an object immersed in a viscous fluid in the vicinity of a purely elastic wall. In this theoretical article, we develop a minimal model incorporating viscoelasticity, carrying out a perturbation analysis in both the elastic deformation of the wall and its viscous damping. Our approach reveals the singular-perturbation nature of viscoelasticity to soft lubrication. Numerical resolution of the resulting nonlinear, singular, and coupled equations of motion reveals peculiar effects of viscoelasticity on confined colloidal mobility, opening the way towards the description of complex migration scenarios near realistic polymeric substrates and biological membranes. Published by the American Physical Society 2024

Anticorrosion and rheological properties of Calyptocarpus vialis extract as a green coating for mild steel in 2MH2SO4

This study assesses the rheological properties and corrosion inhibition efficacy of Calyptocarpus vialis (CV) extract, a wild plant in Asteraceae family. Shear and dynamic rheology studies show that CV extract has shear-thinning behaviour, with viscosity changes occurring at higher shear rates, most likely owing to aggregate formation. These aggregates may develop due to certain solvent characteristics and a jamming tendency is due to the presence of extract phytochemicals. Dynamic rheology confirms its viscoelastic nature. Corrosion inhibition effectiveness was investigated using Mild Steel (MS) in 2 M H2SO4, resulting in an 82.69 % inhibition with an extract concentration of 1 g/L. Adsorption isotherm indicates phytochemical adsorption on MS surface. Contact angles of polished MS (87.30°), with extract (80.10°), and without extract (51.25°) show decrease in wetting and increase in hydrophobicity which indicates that a thin protective layer is formed at MS surface. FE-SEM (Field Emission Scanning Electron Microscopy) images reveal that the CV extract forms a protective barrier on the MS surface, significantly reducing corrosion as compared to the unprotected surface exposed to the mild acid solution. Theoretical calculations, including Density Functional Theory (DFT) simulations, Monte Carlo (MC), and Molecular Dynamics (MD) simulations, support the experimental findings, elucidating phytochemicals adsorption on the MS surface. Further research is required to examine the scalability of CV extracts for industrial applications, as well as their long-term stability and efficacy in various corrosive conditions.

Elastic contribution of polymeric fluids augments salinity-gradient-induced electric potential across a microfluidic channel

HypothesisHarnessing electrical energy from salinity gradients, particularly for powering micro and nanoscale devices, has become a focal point of recent research attention, due to its renewable and biocompatible nature. Much of the reported research in that direction revolves around optimizing the membrane architecture and the charge distribution to maximize the induced electric potential, with no particular emphasis on the fluid rheology. However, many of the modern miniature systems, typically the bio-inspired ones, concern fluids with complex rheological characteristics, where the results for Newtonian solvents may not trivially apply. Here, we hypothesize that the interplay between interfacial electro-mechanics and the fluid rheology can influence the effectiveness of salinity-gradient-modulated electrokinetics significantly – an aspect that has largely remained overlooked. Theory and experimentsHere we report the first experiments supplemented by a theoretical model that unveil how that the addition of polymers in a solvent modulates the salinity gradient – induced electric potential in a microfluidic channel. Our theoretical framework considers the simplified Phan-Thien Tanner (sPTT) constitutive model, which represents the viscoelastic characteristics of fluids. Experiments were conducted with combined pressure driven and salinity gradient driven flow through microchannel involving dilute solutions of polyethylene oxide (PEO) of different molecular weights and concentrations to successfully validate the theoretical approach. FindingsOur findings indicate that the induced electrical potential increased non-linearly with the saline concentration ratio across the microchannel, as compared traditional linear response. Our results demonstrate how the elasticity of fluid may enable realizing an optimal benefit to this effect, by arresting the viscous resistance and uplifting the elastic response via utilizing polymeric inclusions of high relaxation times. These results provide specific insights on preferential windows of augmenting the induced streaming potential by harnessing the viscoelastic nature of the solution and the imposed salt concentration, bearing critical implications in miniature energy harvesting and desalination technology.

THE ROLE OF POLYMERS IN ADVANCING PETROCHEMICAL INDUSTRIES DURING CRUDE OIL EXTRACTION PROCESSES

Polymers, with their viscoelastic nature and complex molecular structure, significantly enhance oil recovery (EOR). This text elucidates the mechanisms underpinning their application in EOR, categorizing them into synthetic and natural (bio) polymers, each with distinct properties. A variety of EOR techniques employing polymers, like foam, alkali-polymer, surfactant-polymer, alkali-surfactant-polymer, and polymeric nanofluid flooding. Most polymers are pseudoplastic under shear, with biopolymers offering the benefits of salt resistance and thermal stability; however, plugging might result in the wellbore area, and they degrade. Despite its complexities, associative polyacrylamide shows promise, though hydrolyzed polyacrylamide remains the industry standard. Notably, alkali-surfactant-polymer flooding proves effective at various scales, and polymeric nanofluids hold potential for future EOR applications.

Comparative study on rolling resistance force in tire-ice interaction with a variation of tread rubber compound

Abstract The complex phenomenon involved in the tire-ice interaction can be better understood by studying the tire and ice properties. A significant force at the contact patch is the rolling resistance force. To study the effect of tire characteristics on rolling resistance forces, data collected from a free-rolling tire can be used as there is no tractive or braking torque applied to the wheel and thus the data representing the longitudinal forces is only related to resistive forces viz. friction and rolling resistance force. Although a lot of research and literature has been developed for tire-ice interaction over the years, there is a significant lack of work in the subsection of free-rolling tires specifically to study the effect of ice parameters on rolling resistance forces. To fulfill the aim of this study, several sets of experiments for 16 winter tires of 8 different rubber compounds in free-rolling conditions were conducted. The experimental data was compared with predictions of 4 well-known formulations from the literature. Based on the findings and the relative error between the predicted and measured values, it was proposed that the high error percentage could be due to the variation in the viscoelastic properties of the tread rubber. The longitudinal force generated during those tests would thus be a combination of frictional forces due to adhesion between the tread rubber and its viscoelastic nature in addition to the contribution from the remaining sections of the tire. The data collected from the experiments and results from implementing the existing models to obtain frictional force will further help in analyzing the relation between the rolling resistance force with variation in normal load, inflation pressure, and change in camber angle once a generic formulation considering the rubber compound effects is incorporated. Another significant finding of this work is that formulations in literature used for finding the rolling resistance coefficient of radial passenger car tires were found to highly underestimate the coefficient when compared to the equivalent coefficient of friction found from experimental results. The future scope may include the development of a model which will incorporate the viscoelastic properties, especially the loss moduli and loss tangent to evaluate the coefficient of friction and rolling resistance force in the free-rolling condition of a winter tire on ice as the rolling resistance losses are found to be highly correlated to these two properties.

Binary phase separation in strongly coupled plasma

We investigated the two-dimensional binary phase separation process of plasma species using classical molecular dynamics in the strongly coupled regime. Both the plasma species interact via a pairwise screened Coulomb (Debye–Hückel) potential; however, the screening parameter κ is different for like- and unlike-species and is the cause for phase separation. We characterize the separation process by measuring the domain growth of equilibrium phases as a function of time—generally, the more significant the inhomogeneity in pairwise interaction, the faster the domain growth. Typically, the domain growth follows a power law in time with an exponent β characterizing the underlying coarsening mechanism. We demonstrate that the growth law exponent is β=1/2 for equal-number-density mixtures and 1/3 otherwise. Further, by comparing these with the corresponding growth laws in binary mixtures of viscous fluids, we show that the viscoelastic nature of plasma fluid modifies the coarsening dynamics, which in turn leads to the observed growth law exponents, notably in the unequal-number-density case.

Rheological Characteristics of Hyaluronic Acid Fillers as Viscoelastic Substances.

Hyaluronic acid (HA) fillers are widely used in esthetic medicine and are categorized into biphasic and monophasic types based on their manufacturing processes. To evaluate the quality of these fillers, it is essential to understand their rheological properties, which reflect their viscoelastic nature. Rheology, the study of material deformation and flow, reveals how fillers behave under stress, combining properties of solids and liquids. This study explores the fundamental principles of elasticity and viscosity, rooted in Hooke's law of elasticity and Newton's law of viscosity, to explain the complex behavior of viscoelastic substances like HA fillers. The distinction between biphasic and monophasic fillers lies in their chemical cross-linking processes, which impact their molecular weight, structure, and ultimately, their clinical performance. Biphasic fillers with minimal cross-linking rely on natural molecular entanglements, exhibiting lower modification efficiency and greater elasticity. Conversely, monophasic fillers, which undergo extensive chemical cross-linking, demonstrate higher modification efficiency, firmer texture, and enhanced resistance to enzymatic degradation. The study emphasizes the importance of thoroughly removing residual cross-linking agents to ensure filler safety. Understanding these rheological characteristics aids clinicians in selecting appropriate fillers based on injection sites, tissue conditions, and desired outcomes, balancing viscoelastic properties and safety for optimal esthetic results.

Enhancing Gluten-Free Muffins with Milk Thistle Seed Proteins: Evaluation of Physicochemical, Rheological, Textural, and Sensory Characteristics.

This study investigated the potential utilization of milk thistle seed protein (MTP) isolates in gluten-free muffins to enhance the protein quantity and technological attributes. MTP was employed to partially substitute a blend including equal amounts of rice flour and corn starch (RCS) at 3%, 6%, 9%, and 12%. The study encompassed a rheological assessment of muffin batters and physicochemical, textural, and sensory analyses of the muffins. The consistency coefficient (K) of muffin batters exhibited an increase with the incorporation of MTP, with all batters demonstrating shear-thinning behavior (n < 1). The dough samples exhibited solid-like characteristics attributed to G' > G″, indicative of their viscoelastic nature. The storage modulus (G') and loss modulus (G″) escalated with higher levels of MTP, suggesting an overall enhancement in dough viscoelasticity. The muffin containing wheat flour displayed the lowest hardness value, followed by MTP-added muffins at ratios of 12% and 9%. Additionally, MTP-added muffins exhibited greater springiness values than control samples without MTP (C2). However, the oxidative stability of MTP-added muffins was lower than the wheat control muffin (C1) and gluten-free control muffin. The protein content in muffins increased with MTP addition, reaching parity with wheat flour muffins at 6% MTP replacement. Sensory analysis revealed that substituting RCS with up to 6% MTP did not significantly alter the overall quality (p > 0.05), whereas higher MTP levels (9% and 12%) led to a decline in sensory attributes. Incorporating MTP at up to 6% yielded protein-enriched muffins with sensory characteristics comparable to the wheat flour muffin (C1). Furthermore, higher MTP additions (9% and 12%) conferred more favorable textural properties than the C2 muffin. However, the oxidative stability of the control muffins was found to be higher than that of MTP-added muffins. This study suggested that MTP could be a potential ingredient to increase the protein amount and specific volume of gluten-free muffins and to improve textural attributes such as springiness and hardness.

Instability of double-diffusive magnetoconvection in a non-Newtonian fluid layer with cross-diffusion effects

The study explores the initiation of two-dimensional double-diffusive convection in a horizontal layer of an electrically conducting non-Newtonian Navier–Stokes–Voigt fluid, subjected to a uniform vertical magnetic field and cross-diffusion effects. The numerical results are presented by obtaining the analytical solutions for both steady and oscillatory onset scenarios. The viscoelastic nature of the fluid either delays or hastens the onset of oscillatory convection depending on the strength of solute concentration. The analysis also uncovers contradictions in the linear instability characteristics with and without cross-diffusion terms, even when other input parameters are identical. Under specific conditions, three novel phenomena are observed that are not typically seen in double-diffusive cases: (i) an electrically conducting Navier–Stokes–Voigt fluid layer, initially linearly stable in the presence of a magnetic field, can become destabilized with the addition of a heavy solute to the fluid's bottom; (ii) a stable double-diffusive electrically conducting Navier–Stokes–Voigt fluid layer can be destabilized by the application of a magnetic field; and (iii) the requirement of three critical values of the thermal Rayleigh number to determine linear instability, as opposed to the usual single value owing to the existence of disconnected closed convex oscillatory neutral curves. The results are shown to align with previously published findings in the limiting cases.

Novel heat exploration investigation for bioconvected Oldroyd-B nanofluid with variable thermal conductivity and Arrhenius energy induced by nailed boundary

Oldroyd-B nanofluids have potential applications in enhanced heat transfer systems, drug delivery, and advanced material processing due to their unique rheological properties. Bioconvection finds applications in biomedical research, environmental monitoring, and optimizing fluid dynamics in biotechnological and pharmaceutical processes. Due to these applications current study investigates bioconvection in the flow of Oldroyd-B nanofluid subjected to Joule heating with convected boundaries. For uniqueness of problem the effects of variable thermal connectivity and activation energy are taken into account. In addation the influence of heat source and thermal radiation are part of current model. The governing PDEs of mathematical model incorporates the Oldroyd-B rheological framework to capture the viscoelastic nature of the fluid are transformed into ODEs via similarity solution. Matlab platform via shooting algorithm is involved to solve transformed system. Through numerical simulations the stimulus of involving parameters on velocity f ′(η) temperature θ(η), concentration ϕ(η), and microbes profile X(η) are displayed in graphical and tabulated form. For strength of problem the streamlines and graphs of physical quantities are also designed. It is noted that velocity curve decreased for increasing value of magnetics parameter and opposite trend is noted in velocity distribution for increasing value of mixed convection parameter λ . Moreover, thermal layer θ is diminished for growing value of Pr , a reverse relation is noted in concentration profile for value of activation energy.

Development and characterisation of nutritionally enriched honey filling as novel alternative to commercial fat-based filling for bakery applications

This research aimed to develop a novel bakery filling ingredient using honey by incorporating watermelon rind (WMR) paste and xanthan gum (XG) as an alternative to conventional fat-based fillings. The study effectively optimised honey filling preparation using a Box-Behnken design, considering variables three key independent variables: WMR paste (10–30 % w/w of honey weight), XG (1–1.5 % w/w of honey weight), and vacuum drying time (5–10 h). The impact of these was systematically evaluated across baking stability, total phenolic content (TPC), firmness, and water activity of the honey filling. The optimal conditions for honey filling preparation were identified as 27.31 % WMR paste, 1.1 % XG, and a drying time of 8 h and 54 min. The incorporation of WMR paste led to notable improvements of TPC, total flavonoid content (TFC), antioxidant capacity; however, XG played a vital role in enhancing the baking stability and viscoelastic nature of honey filling samples. To comprehensively assess the physicochemical, rheological, and thermal characteristics, a comparison was drawn between raw honey, optimised honey filling (OHF), and a commercial chocolate filling (CCF) as a reference. The CCF exhibited slightly higher viscoelastic behaviour but lower structural stability in comparison to OHF. On the other hand, OHF demonstrated thermal properties like those of the CCF, with enhanced antioxidant activity, lower moisture content, and minimal fat content. Therefore, OHF introduces a bakery filling option as an alternative to CCF, with superior nutritional value and enhanced rheological stability.