Pseudoplastic Materials Research Articles

Disorder optimization in the mixed convective dynamics of nonlinear shear thinning materials with the significance of wavy surface amplitude and thermal resistance

A mixed convective driven wavy motion of the pseudo-plastic materials is very significant in different practical fields, like the production of paints and ketchup, etc. Blood flow through wavy vessels is another very practical aspect of this study. Energy conversion processes and effective resource use are one of the burning and hot topics when studying heat flow rate through materials. Main theme of this work is to optimize the heat energy conversion by introducing irreversible viscous dissipation and thermally radiative factors. In particular cases, the heat flow rate needs to be enhanced for low energy consumption. This is why, in such cases, the wavy surface flows are preferred by plane surfaces. The proposed problem is presented with highly non-linear mathematical equations. Some assumptions and variables address the mathematical equations in easily solvable forms. The findings are shown regarding the material's velocity, concentration, temperature, resistive forces, and heat-mass flow rates. A remarkable reduction in liquid velocity and enhancement in concentration and temperature is observed with the variation in amplitude of the wavy surface. The irreversible process is maximized due to the higher involvement of temperature ratio and thermal radiation factors, respectively. The ratio of infinite and zero shear rate viscosities reduced the concentration of the liquid. For method validation, a best-matched comparison is provided with literature.

Plant-Based Emulsions as Dairy Cream Alternatives: Comparison of Viscoelastic Properties and Colloidal Stability of Various Model Products.

In the context of growing interest in plant-based food products for their potential health benefits and sustainability, this study investigates the effect of mono- and diglycerides of fatty acids application on physico-chemical properties of various plant-based cream products, compared to lecithin application in rice cream. Rheological and textural parameters, colour profile, and colloidal stability were analysed. The application of mono- and diglycerides modified the creams' viscoelastic behaviour, showing a decrease in viscoelasticity across the samples; although in oat-coconut cream resulted in a higher viscoelasticity, indicating the formation of a gel-like structure. Rice cream with lecithin emulsifier showed lower viscoelastic properties characterised by higher phase angle (tan δ). All samples behaved as pseudoplastic materials (with a flow behaviour index n < 1). For coconut and almond creams, the consistency coefficient increased and flow behaviour index decreased after emulsifier application. Interestingly, the emulsifier addition did not significantly affect the cream's colour profile, characterised by yellow hue angle (h*) as a dominant spectral component. The colloidal stability, indicated by a stability index (SI), was determined as well.

Comparative numerical and analytical computations for magnetized pseudoplastic materialwith roll-coating applications

The phenomenon of wire coating occurs in various applications in manufacturing systems, cables, drawing of sheets, polymer industries etc. The current investigation deals with the study of the reverse coating phenomenon of magnetized non-Newtonian fluid. A pseudoplastic material with applications of magnetic force is considered and the rheological impact based on the non-Newtonian model is investigated. The thin layer of pseudoplastic material is coated when it travels due to the small gap conveying by two reverse coating rollers. The formulation of problem is based on lubrication approximation theory. Both analytical and numerical simulations are performed, and the corresponding results are compared. The numerical assessment is based on the shooting technique while analytical outcomes are obtained using perturbation technique. The effects of the governing parameters on the flow profiles are depicted. The main parameters influence the flow are the Weissenberg number and velocity ratio parameter.

Coating of pseudo-plastic material in reverse roll-coating: Mathematical analysis

This paper describes a theoretical framework and computational methods of a thin layer coating of a non-Newtonian polymeric material while it moves through a tiny space among two inverted rollers. Order of magnitude is accustomed to clarify the nondimensional forms of the governing equations. Semi-analytical solutions of pressure gradient, velocity profile and rate of the flow are acquired via optimal homotopy asymptotic method (OHAM). The graphical representation depicts the physical quantities of the effects of velocity profile ratio k and Weissenberg number We. It is observed that by increasing the values of k and We, velocity profile decreases while pressure distribution increases.

Aerial additive manufacturing with multiple autonomous robots.

Additive manufacturing methods1-4 using static and mobile robots are being developed for both on-site construction5-8 and off-site prefabrication9,10. Here we introduce a method of additive manufacturing, referred to as aerial additive manufacturing (Aerial-AM), that utilizes a team of aerial robots inspired by natural builders11 such as wasps who use collective building methods12,13. We present a scalable multi-robot three-dimensional (3D) printing and path-planning framework that enables robot tasks and population size to be adapted to variations in print geometry throughout a building mission. The multi-robot manufacturing framework allows for autonomous three-dimensional printing under human supervision, real-time assessment of printed geometry and robot behavioural adaptation. To validate autonomous Aerial-AM based on the framework, we develop BuilDrones for depositing materials during flight and ScanDrones for measuring the print quality, and integrate a generic real-time model-predictive-control scheme with the Aerial-AM robots. In addition, we integrate a dynamically self-aligning delta manipulator with the BuilDrone to further improve the manufacturing accuracy to five millimetres for printing geometry with precise trajectory requirements, and develop four cementitious-polymeric composite mixtures suitable for continuous material deposition. We demonstrate proof-of-concept prints including a cylinder 2.05 metres high consisting of 72 layers of a rapid-curing insulation foam material and a cylinder 0.18 metres high consisting of 28 layers of structural pseudoplastic cementitious material, a light-trail virtual print of a dome-like geometry, and multi-robot simulations. Aerial-AM allows manufacturing in-flight and offers future possibilities for building in unbounded, at-height or hard-to-access locations.

Experimental and Theoretical Study of the Flow Characteristics of Rubber Compounds in an Extruder Screw

AbstractWe describe an experimental and theoretical study of the mechanisms of flow of rubber compounds in a screw extruder. Two compounds, a typical synthetic rubber (butadiene-styrene copolymer-cis-1, 4 polybutadiene) based passenger tire tread (PTT) and a natural rubber based truck tire tread (TTT), were investigated in a 112${}^{1}/{}_{2}$inch NRM cold feed screw extruder using a screw with a constant channel depth and constant channel pitch along the whole screw length. The rubber was cured in place and the screw removed. The screw exhibited starvation behavior except near the die. The length of the rubber strip in the screw is proportional to the pressure developed at the die. Marker studies showed transverse circulating flows beginning in the region immediately downstream from the hopper. These observations indicate that cold feed extruders exhibit a metering region flow, albeit sometimes starved, from entry port to die. Under these conditions the extruder is independent of the pressure developed in the screw channel. A simple non-Newtonian isothermal mathematical model for the metering zone is described. The rubber compound is considered as a pseudoplastic material with a yield value. A comparison of theory and experiment shows that a one dimensional isothermal model quite accurately predicts the flow rate pressure development of the rubber compound in our screw (with a shallow prismatic channel) when starvation is considered. The yield value of the rubber compound influences screw characteristic curves only for very high values of the dimensionless pressure gradient.

A Galerkin strategy for tri-hybridized mixture in ethylene glycol comprising variable diffusion and thermal conductivity using non-Fourier’s theory

Abstract This research is conducted to investigate heat and mass transport past over a stretched surface having pores in a pseudo-plastic model. To study porosity effect, Darcy Forchheimer relation is used. Thermal and mass transport expressions are derived by engaging the double diffusion theories as extensively used by researchers proposed by Cattaneo and Christov. Furthermore, the thermal performance is studied by mixing the tri-hybrid nanoparticles in a pseudo-plastic material. The phenomenon of boundary layer is used to derive the complex model. The correlation for tri-hybrid nanoparticles is used to convert the model partial differential equations into ordinary differential equations (ODE) along with appropriate similarity transformation. The transfigured ODEs are coupled nonlinear in nature, and the exact solution is not possible. To approximate the solution numerically, finite element scheme (FES) is used and code is developed in MAPLE 18.0 for the graphical results, grid independent survey, and tabular results. The obtained results are compared with the published findings that confirm the accuracy and authenticity of the solution and engaged scheme. From the performed analysis, it is concluded that FES can be applied to complex engineering problems. Furthermore, it is monitored that nanoparticles are essential to boost the thermal performance and higher estimation of Schmidt number control the mass diffusion.

Rheological and tribological characterization of different commercial hazelnut-based spreads.

Five commercial hazelnut/cocoa spreads with different compositions were tested by rheology/tribology. The impact of each formulation on the structural/lubricant performances was investigated. Rotational/oscillatory rheology was chosen to assess material behavior during flow. Viscosity variation as a function of temperature and chamber geometry was evaluated. Oscillatory mode tests were carried out to obtain information on product viscoelasticity. Tribological analysis was performed at different temperatures aiming at simulating the chewing/swallowing process. All samples were categorized as pseudo-plastic and viscoelastic materials, with the elastic component prevailing over the viscous one. Major differences were detected in terms of consistency index, depending on the total lipid content. Temperature increase enhanced spread fluidity with a decreasing viscosity according to the Arrhenius model (R2 > 0.942) and greater values of activation energy reflecting higher sensitivity to microstructural changes. An inverse relationship between Casson viscosity and sugar/fat ratio highlighted additional correlations between structural parameters and spread formulation. Tribological measurements at 25°C highlighted that, at the initial eating stage, the friction factor (0.112-0.262 at sliding velocity of 8× 10-6 m/s) was strongly affected by either the amounts of solid fat or hazelnut percentage. Tribological data corroborated the theory for which tribology and rheology cover different domains.

Thermal Improvement in Pseudo-Plastic Material Using Ternary Hybrid Nanoparticles via Non-Fourier’s Law over Porous Heated Surface

The numerical, analytical, theoretical and experimental study of thermal transport is an active field of research due to its enormous applications and use in numerous systems. This report covers the impacts of thermal transport on pseudo-plastic material past over a horizontal, heated and stretched porous sheet. Modeling of energy conservation is based upon a generalized heat flux model along with a heat generation/absorption factor. The modeled phenomenon is derived in the Cartesian coordinate system under the usual boundary-layer approach proposed by Prandtl, which removes the complexity of the problem. The modeled rheology is obtained in the form of coupled, nonlinear PDEs. These derived PDEs are converted into ODEs with the engagement of similarity transformation. Afterwards, converted ODEs containing some emerging parameters have been approximated numerically with a powerful and effective scheme, namely the finite element approach. The obtained results are compared with the published findings as a limiting case of current research, and an excellent agreement in the obtained solution was found, which guarantees the effectiveness of the used methodology. Furthermore, it is recommended that the finite element approach is a good method among other existing methods and can be effectively applied to nonlinear problems arising in the mathematical modeling of different phenomenon.

Sheared Thick‐Film Electrode Materials Containing Silver Powders with Nanoscale Surface Asperities Improve Solar Cell Performance

Thick‐film screen‐printed fine‐line metallization is one of the most important process steps in the whole production chain of photovoltaic cell manufacturing as variations in industrial solar cell performance mainly depend on electrode properties. The impact of Ag powder surface topography on viscoelastic characteristics and geometry of solar cell electrodes is studied. Numerical simulations for concentrated non‐Brownian suspensions show that shear viscosity and storage modulus increase with particle roughness. Experimental rheological analysis shows improvement in thixotropy and shear storage modulus for pseudoplastic electrode materials with corrugated Ag powders. Consequently, viscoelastic recovery is enhanced for frontside electrode gridlines with rough‐surface Ag powders. This results in aspect‐ratio and cross‐sectional symmetry enhancement for rough‐surface Ag powder gridlines compared with smooth‐surface Ag powder gridlines. Rough‐surface Ag powder gridlines have smaller height variations, making them more suitable for high‐throughput screen printing. Optical simulations show improved light redirection into the solar cell for gridlines formed from rough‐surface Ag powders, leading to higher solar cell photocurrent. The improved gridline definition results in an increase in short‐circuit current density, yielding average efficiency improvement of ≈0.1% absolute for monocrystalline‐Si solar cells with screen‐printed gridlines having rough‐surface Ag powders. This results in monocrystalline‐Si solar cells with 22.45% average conversion efficiency.

Effect of Ethylene-Ethyl Acrylate Copolymer on the Rheological Properties of LDPE/PLST Blends

The rheological properties of polyethylene/starch blends compatibilized with ethylene–ethyl acrylate copolymer (EEA) were investigated at different temperatures and shear rates. According to the Fourier transform infrared spectroscopy (FT-IR) data, the application of EEA as a compatibilizer did not lead to the significant change in the blends’ band spectra because the concentration of acrylate groups (and consequently that of carbonyl groups) in the blends was low and the degree of hydrogen bonding was small enough. The rheological properties of blends showed that the melts of the blends were pseudoplastic materials. Viscosity of melt for all blends increased with an increase in both EEA and starch content. Power law index measurements showed that the n value increased and was less than one and the K value decreased with the increase in EEA content. Blends with higher content of starch had the lowest value of activation energy (Ea) and the sensitivity of blends to temperature decreased with an increase in starch content.

Development of fiber flow finishing (FFF) process for polishing hip prostheses

In this paper, a new polishing process has been developed based on a smart polishing media called fiber flow finishing (FFF). The proposed polishing media included styrene butadiene rubber (SBR), coarse sisal fibers, and naphthenic oil. During the process, the rheological behavior of the polishing media changes intelligently due to severe mechanical disintegration and chemical treatment. This intelligent behavior is very similar to the behavior of pseudo-plastic materials. To evaluate the polishing performance, experiments were performed on the femoral head of hip prostheses grade ASTM F138 (SS 316L) for the different number of finishing cycles to investigate its effect on the percentage change in surface roughness (%ΔR a ). The experimental results clearly showed that the %ΔR a of the femoral head is low in the initial finishing cycles (i.e., up to 200 working cycles), while the %ΔR a increases to 72.54% with an increase in the number of finishing cycles up to 1000. Moreover, the surface morphology of the specimens well substantiated that the FFF process performed a kind of surface modification on the surface texture of the femoral head, resulting in a smooth and uniform surface finish without surface defects that is as a mirror. • The fiber flow finishing (FFF) process is first developed for polishing hip prostheses. • The surface finish of the femoral head was improved by 72.54% using the FFF process. • The FFF process performed a kind of surface modification on the femoral head surface. • The FFF process has a better performance than the abrasive flow finishing (AFF) process. • The FFF process has a promising future to improve surface integrity of industrial parts.

Virtual parameter identification of the forming behaviour of discontinuous fibre reinforced thermoplastic composite sheets

Fibre-reinforced thermoplastics (FRTP), such as organo sheets or laminates, are increasingly being used in large-scale automotive production. The high weight-saving potential, high specific strengths and stiffnesses as well as processing times suitable for large-scale production are some of the reasons for using these materials. However, the formability of such semi-finished products is severely limited by the fibre reinforcement, which can lead to fibre breakage, fibre displacement or wrinkling in complex-shaped components. In order to increase the formability, an FRTP semi-finished product is developed, which consists of discontinuous tapes. Due to the local sliding of the tape sections, a pseudo-plastic material behaviour is achieved. Experimental uniaxial tensile tests at elevated temperatures are used to investigate the forming behaviour of the material for different tape lengths and overlap lengths. Subsequently, this tensile test is numerically modelled in order to fit the pseudo-plasticity to the experimental data by a virtual parameter identification. With the help of the parameters determined from the numerical tensile test, the sliding behaviour of the tape sections can be used for forming simulations in order to achieve a higher prediction quality.

3D printing and additive manufacturing of cereal-based materials: Quality analysis of starch-based systems using a camera-based morphological approach

Structural control over cereals' crumb matrix is achievable using 3D printing. The manipulation of the cellular structure including void fraction, pore size, geometry, and distribution is achievable by resolving large structures into finite layers. However, investigating the applicability of material extrusion for printing starch and cereal-based systems is of great interest due to the behavior of the thixotropic and pseudoplastic materials during extrusion and their viscoelastic post-printing geometric response. In this study, we use an on-board camera system composed of top- and side-view cameras to characterize the post-printing geometrical attributes of two cereal-based systems, which comprise of wheat flour dough and wheat starch-egg white protein blends. This quantitative method uses image processing techniques to obtain morphological dimensional parameters. Furthermore, the induced defects involving printing delays and under-extrusion are influenced by the material's yielding behavior. Over-extrusion defects are dominant in printing wheat flour dough due to the network formation of gluten which caused the collapse of the uppermost layer. Moreover, the structural collapse behavior for the printing ink systems is obtained concerning the hydration level of the dry components. For the first time, the quality behaviors and dimensional attributes were quantitatively studied using on-board imaging and analysis of 3D printed cereal-based morphologies.

Analysis of radiative magneto nano pseudo-plastic material over three dimensional nonlinear stretched surface with passive control of mass flux and chemically responsive species

PurposeThe current determination is committed to characterize the boundary layer flow of Williamson nanofluid prompted by nonlinear strained superficial under heat and mass transport mechanisms. Buongiorno model is presented to view the influence of nanoparticles in fluid flow. Scrutiny has been conceded under the action of the transversely smeared magnetic field. Heat and mass relocation exploration are conducted in the companionship of radiation effects and actinic compensation.Design/methodology/approachSimilarity variable is designated to transmute nonlinear partial differential equations of conservation laws of mass, momentum, energy and species into ordinary dimensional expressions. These constitutive and complicated ordinary differential expressions assessing the flow situation are handled efficaciously by manipulating Runge–Kutta–Fehlberg procedure (RK-5) with shooting routine.FindingsThe graphical demonstration is deliberated to scrutinize the variation in velocity, temperature and concentration profiles with respect to flow regulating parameters. Numerical data are displayed through tables in order to surmise variation in skin friction coefficient and Nusselt number. The augmenting values of fluid parameter and magnetic parameter reduces the horizontal fluid velocity, whereas normal velocity upsurges for mounting values of stretching ratio parameter. Moreover, mounting values of radiation parameter and thermophoresis parameter upsurges the temperature profile, whereas, growing values of Prandtl number lessen the temperature field.Practical implicationsThe current exploration is used in many industrial and engineering applications in order to discuss the transport phenomenon.Originality/valueFlow over a nonlinear stretched surface has numerous applications in the industry. The present attempt examines the combined influence of various physical characteristics for the flow of Williamson fluid and no such attempt exist in the available literature.

Assessment of pseudo-plastic and dilatant materials flow in channel driven cavity: application of metallurgical processes

Non-Newtonian fluid rheology representing the properties of pseudoplastic and dilatant materials has received overwhelming attention due to extensive applications in industrial and technological sectors like in metallurgical processes, shock absorbing materials, smart structures, and devices with adaptive stiffness, damping, emulsions, suspensions and so forth. Thus, in current communication characteristics of power law fluid elucidating attributes of pseudoplastic and dilatant materials in channel driven cavity is addressed. Finite element method (FEM) is implemented to interpret rheological features of power law fluid by varying flow controlling parameters. Discretization of domain at coarse level is performed by using stable first and second order polynomial (P2−P1) shape functions. Square shaped cylinder is placed at (1, 1.5) above the cavity. Hydrodynamics forces like pressure difference drag and lift variations are measured at outer surface of cylinder. The impact of primitive parameters like power law index (n) and Reynold number on velocity, pressure and viscosity for shear thinning and thickening cases is adorned. It is deduced that pressure difference increased against the variation in power law index. In similar way the impact of drag and lift forces mounts by increasing power law index. Reynold number has delineating impact on drag and lift forces near the obstacle. It is also seen that pressure shows optimized non-linear behavior near the obstacle and becomes linear along the downstream as expected in channel flow. It is divulged that pressure drops more rapidly for increasing magnitude of Reynold number. Velocity of fluid increases when power law fluid flow is behaving as shear thinning fluid in comparison to shear thickening case.

Effect of Different Starches on the Rheological, Sensory and Storage Attributes of Non-fat Set Yogurt.

This study was conducted to investigate the effect of various native starches on the rheological and textural properties of non-fat set yogurt. The yogurt samples were prepared while using five types of starches (potato, sweet potato, corn, chickpea, and Turkish beans). The physical properties of the prepared yogurt were analyzed while using shear viscosity, viscoelasticity, and texture analysis. The tests were performed after 0, 7, and 15 days storage. The effect of these starches on the yogurt viscoelastic properties, texture, syneresis, and sensory evaluation were determined under optimum conditions. The results showed that adding 1% starch could significantly (p < 0.05) reduce syneresis and improve yogurt firmness. Starches exhibited different effect on the overall quality of the yogurt due to their origin and amylose content. Regardless of the number of storage period duration, all of the samples, including the control behaved as pseudoplastic materials (n < 1) with various levels of pseudoplasticity. Yogurts with corn and tuber starches had the highest consistency coefficient (k), which indicated higher viscosity. The yogurt sample with chickpea starch exhibited the highest G´, making the gel more solid like. Therefore, the influence of tuber starches (potato and sweet potato) on G´ was different when compared to corn or legume starches. The behavior of the starches changed with storage time, where some starches performed better only at the beginning of the storage period duration. Wheying-off was significantly reduced, regardless of starch type. The pH of the yogurt remained unchanged through storage. Sensory evaluation showed a preference for starch-containing samples as compared to the control, regardless of the starch type. The variation in yogurt quality as a function of starch type could be attributed to the starch granule structure, gelatinization mechanism, or amylose content.

Numerical investigation for Soret–Dufour and induced magnetic field effects on MHD peristalsis of pseudoplastic material

Endoscopy in the peristalsis of pseudoplastic material with Soret, Dufour, and chemical reaction effects is addressed. An induced magnetic field is also discussed. A lubrication approach is followed for the development of the related equations. The governing problems are numerically solved. Graphs are provided for physical interpretation. The significant findings of the study include the activation of velocity and temperature and the reduction of an induced magnetic field, current density, concentration, and heat transfer coefficient when the electric current is enhanced. There is a qualitatively similar result for the magnetic Reynolds number on the current density and induced magnetic field.

Many-body dissipative particle dynamics (MDPD) simulation of a pseudoplastic yield-stress fluid with surface tension in some flow processes

The dynamics of Newtonian and pseudoplastic yield-stress fluid drops impacting on solid surfaces are studied numerically by the many body dissipative particle dynamics (MDPD) method. The pseudoplastic yield stress fluid is modelled by two groups of different MDPD particles, in which the parameters are tuned so that the overall fluid behaves in a similar manner to the Herschel–Bulkley pseudoplastic material in simple shear flow. The droplet characteristics are measured by its central drop diameter and its height, and an effective unyielded region is observed in the drop impacting process. The MDPD simulation results compare well with previous drop impact experiments and simplified theoretical studies on the slump test, serving to demonstrate the capability of the MDPD method to explore yield-stress fluid drop’s flow processes.

Characteristics of β-glucan extracted from raw and germinated foxtail (Setaria italica) and kodo (Paspalum scrobiculatum) millets

β-glucan extracted from raw and germinated foxtail and kodo millets were evaluated for its functional, rheological and in vitro antioxidant characteristics. The in vitro activity determined in terms of diphenyl-p-picryl hydrazy (DPPH) radical scavenging activity and Ferric reducing antioxidant power (FRAP) activity was found higher in germinated kodo millet (78.74%, 48.98%) compared to foxtail millet (34.96%, 38.67%), respectively. Water binding capacity and swelling power of β-glucan extract of foxtail millet increased from 2.88 g/g to 3.06 g/g and 1.32 g/g to 1.67 g/g and that of kodo millet from 3.45 to 3.99 g/g and 2.54 to 2.99 g/g, respectively, after germination. There was a significant improvement in foaming capacity and stability of β-glucan after germination. The ‘n’ values were less than unity indicated that β-glucan extracts behaved pseudo-plastic like material. The storage modus (G′) of β-glucan extracts of germinated kodo millet was higher than foxtail millets, as well as overall higher than the loss modulus (G″) indicating a dominantly viscoelastic behaviour and stability. Peak tanδ was lower for germinated foxtail millet compared to kodo millet indicating more stable gel of the former. Therefore, improvements in the functional as well rheological properties of β-glucan could be exploited in food and pharmaceutical industries.