Bingham Plastic Research Articles

Shear and combustion characterization of printable ammonium perchlorate composite propellant formulations

AbstractSeven formulations of ammonium perchlorate composite propellant (APCP) are developed and their properties relevant for successful additive manufacture are characterized. Extrusion in a custom‐built 3D printing system and spindle viscometry are used to collect viscosity measurements of curing primary and non‐curing secondary versions of the formulations. The formulations that behave similarly to a Bingham plastic, with apparent viscosities between 4 and 8 thousand Pa*s at 30 minutes post‐mix, are determined to be most suitable for printing applications. Measurements of one material show a yield stress of 1 kPa. Ambient pressure burn rates of 2.0–2.9 mm/s were measured for the compositions tested. All measured burn rates were comparable to the lower end of typical burn rates for APCP. The results of the characterization demonstrate a propellant suitable for use in a 3D printing system.

A mechanistic study on the effectiveness of star-like and comb-like polycarboxylate superplasticizers in cement pastes

In this paper, star-like polycarboxylate superplasticizer (SPCE) and comb-like polycarboxylate superplasticizer (CPCE) were prepared via atom transfer radical polymerization (ATRP) to study the mechanism of the effectiveness enhancement resulting from this transformation of topological structure. It was found that SPCE molecules acted higher adsorption amount and more Ca2+ complexes, and formed a lower and more compact adsorbed layer and larger surface coverage with a flat conformation on cement surface, depending on more anchored points per unit volume. Through this mechanism, cement particles adsorbed by SPCE showed stronger dispersible capability and colloidal interaction forces (the steric force was dominant), resulting in lower yield stress and plastic viscosity of the cement paste containing SPCE which behaved as an ideal Bingham fluid. The aim of this study is to clarify the mechanistic correlation between topological structure evolution and effectiveness promotion for PCE.

Gum Arabic-based three-dimensional printed hydrogel for customizable sensors

Most three-dimensional (3D) printed hydrogel exhibit non-idealized rheological properties in the process of direct ink writing and complicated curing. Therefore, accurate writability and convenient curing for 3D printed hydrogel remain a challenge. In this paper, we developed a typical 3D printed hydrogel which realized direct ink writing (DIW) at temperatures similar to human body. Silicon dioxide (SiO2) and Gum Arabic (GA) formed the Bingham fluid to ensure shape stability. The rapid initiation system of potassium persulfat (KPS) and N,N,N′,N′ -tetramethylethylenediamine (TMEDA) allowed the 3D printed hydrogel precursor solution to transiently form a hydrophobic conjoined cross-linking network structure of acrylamide (AAM) and lauryl methacrylate (LMA) after printing, resulting in preferable mechanical properties. Hydrogel precursor solution showed better rheological properties with the nature of Bingham fluids, and achieved transient cross-linking at 30 °C for 10 s in the rheological test. A variety of 3D printed hydrogel with individual strain sensing properties are prepared as customizable sensor that could monitor significant strain signals within 0–20 % strain with high sensitivity. Moreover, they were discovered excellent temperature sensitivity over a wide operating range (0–80 °C). The 3D printing hydrogel sensors were expected to have broad application prospects in flexible wearable devices and medical monitoring.

Laminar planar hydraulic jump during free surface flow of Bingham plastic liquid

The hydrodynamics of laminar planar hydraulic jump during free surface flow of Bingham plastic liquid is investigated through numerical simulation and shallow flow analysis, both validated against experimental results. The singularity of Bingham plastic model at the yield surface is addressed by adopting the Bingham plastic Papanastasiou regularized model with the value of regularization parameter as 1000 s in order to mimic ideal BP flow. The study reveals that an increase in both yield stress and plastic viscosity creates a jump closer to the inlet with a higher film thickness and jump strength. Interestingly, a higher Froude number shifts jump towards channel exit with increased strength while a higher Reynolds number forms a jump of lower strength closer to exit. The jump types noted from simulations are presented as phase diagrams in terms of inlet Reynolds and inlet Froude number for different yield stress values.

Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids

Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids

Infiltration Grouting Mechanism of Bingham Fluids in Porous Media with Different Particle Size Distributions

Although permeation grouting technology has been widely used in engineering practice, there has not been sufficient research on how the distribution of pore sizes in porous media affects the diffusion of grout. In this study, based on the fractal theory of porous media and the Bingham fluid rheological equation, a Bingham fluid permeation grouting mechanism considering the distribution of pore sizes in porous media is proposed. The mechanism is validated through laboratory experiments and numerical simulations using COMSOL 6.0. During the experiments, parallel electrical resistance imaging is employed to monitor the diffusion range of the grout. Furthermore, the effects of grouting pressure, porosity, and water–cement ratio on the diffusion radius of the grout are analyzed. The results show that the Bingham fluid grout diffuses in a semi-spherical shape in the gravel. Additionally, parallel electrical resistance imaging can analyze the diffusion range of the grout in the gravel. The diffusion radius of the Bingham fluid grout in the gravel is smaller than the diffusion radius obtained by considering the particle size distribution theory, with an average difference of 31.8%. Compared to the diffusion radius obtained without considering the particle size distribution theory, the diffusion radius obtained by considering the distribution of pore sizes is closer to the experimental results. The numerically simulated program, which was developed for this study, can effectively simulate the diffusion law of the Bingham fluid in the gravel. So far, the Bingham fluid seepage grouting model considering the different particle size distribution of porous media has been built. The findings of this study can provide theoretical support and technical reference for practical grouting projects.

The Control of Lava Rheology on the Formation of Lunar Sinuous Rilles by Substrate Thermal Erosion: Topographic and Morphometric Relationships with Eruption Rates, Erosion Rates, Event Durations, and Erupted Magma Volumes

We describe a model of the fluid mechanics and thermodynamics of turbulent lava flows capable of thermally eroding sinuous rille channels on bodies without atmospheres. The model assumes Bingham plastic rheology for the lava and shows how the effects of radiant cooling and consequent crystallization change the rheology and control the point at which turbulence ceases. A correlation is found between magma volume eruption rate and the length and width of the eroded rille channel. Thus, simple measurements of rille length and width in images can provide reliable estimates of magma eruption rates. The model also predicts rille floor erosion rates, so that if rille depths are measured, eruption durations and erupted magma volumes can also be found. The model is applied in detail to six well-preserved lunar rilles and more generally to a published catalog of 214 lunar rilles. We find that rille-forming eruptions have magma volume eruption rates of a few times 104 m3 s−1, durations of up to 3 months, and erupted magma volumes up to ∼200 km3, consistent with theoretical predictions of basaltic magma ascent and eruption from deep mantle sources. The key requirement for rille formation, rather than mare lava flow deposit formation, is the turbulent eruption of a sufficiently large volume of low-viscosity magma at a sufficiently low eruption rate.

A consistent three-equation shallow-flow model for Bingham fluids

A consistent three-equation shallow-flow model for Bingham fluids

Numerical investigation of steady state, laminar, natural convection of Bingham fluids in a trapezoidal enclosure heated from the bottom and cooled from the sides

Laminar, steady-state, natural convection of Bingham fluids in trapezoidal enclosures with a heated bottom wall, cooled inclined sidewalls and an adiabatic top wall has been studied based on numerical simulations for a range of values of nominal Bingham numbers, Rayleigh numbers (i.e., 103 ≤ Ra ≤ 105), and sidewall inclination angles (i.e., 30° ≤ φ ≤ 60°) for a representative nominal Prandtl number (i.e., Pr = 103). It has been found that the mean Nusselt number Nu‾ increases with increasing Rayleigh number Ra due to the strengthening of advective transport. An increase in the sidewall inclination angle φ leads to a decrease in the mean Nusselt number Nu‾ due to an increase in the area for heat loss from the trapezoidal enclosure. The value of the mean Nusselt number Nu‾ was found to decrease with increasing Bingham number Bn. At high values of Bingham number Bn, the fluid flow essentially stops within the enclosure and the heat transfer takes place primarily due to conduction and, accordingly, the mean Nusselt number Nu‾ settles to a constant value, for a given value of sidewall inclination angle φ, irrespective of the value of nominal Rayleigh number Ra. Furthermore, a correlation for the mean Nusselt number Nu‾ in trapezoidal enclosures with a heated bottom wall, an adiabatic top wall, and cooled inclined sidewalls accounting for the range of Rayleigh numbers Ra, Bingham numbers Bn and inclined wall angles φ considered which provides adequate approximation of the corresponding values obtained from the numerical simulations has been identified.

Numerical study of irreversibility analysis on pulsatile flow of blood through a ω-shaped stenotic artery

The mathematical modeling of blood flow in a stenotic blood vessel is very important for understanding the effects of various geometric and rheological parameters on the normal flow of blood. The present study is concerned with the heat and mass transfer in the blood flow of a non-Newtonian fluid through a ω-shaped stenotic arterial segment. The non-Newtonian behavior of blood is described mathematically by employing the constitutive equation of the Herschel-Bulkley fluid. The wall of the artery is considered to be rigid having ω-shaped constriction in its lumen. The mild stenosis assumption is used to simplify the fully coupled momentum, energy, and concentration equations as well as the constitutive equation of the Herschel-Bulkley fluid. Numerical solutions for fluid velocity, temperature, mass concentration, and entropy generation are evaluated by using the explicit finite difference scheme. The effects of various emerging parameters on the velocity, wall shear stress, flow rate, temperature, concentration, and entropy distributions have been analyzed in detail. A comparison between different fluid models has also been presented. It is found that the temperature in the Herschel-Bulkley fluid is marginally lower than that of the Newtonian, Power law, and Bingham fluids whereas an opposite trend is noticed in the case of mass concentration.

Secondary flow of an elasto-visco-plastic fluid in an eccentric annulus

In this paper we study the flow an elasto-visco-plastic fluid whose deviatoric stress is made up by a “seemingly” visco-plastic part (regularized Bingham fluid) and a viscoelastic part (Rivlin–Ericksen fluid) in a “slightly” eccentric annulus. The flow is driven by an applied horizontal pressure gradient and by the motion of the inner cylinder. Using the eccentricity as perturbation parameter we show that secondary flows appear at the first order approximation. We investigate the various flow patterns depending on the different non-dimensional groups appearing in the governing equations. In particular we observe the occurrence of rotating and counter-rotating vortices depending on the material and geometrical parameters of the system.

Wall slip effects in Rayleigh–Bénard convection of viscoplastic materials

PurposeAccording to the research, viscoplastic fluids are sensitive to slipping. The purpose of this study is to determine whether slip affects the Rayleigh–Bénard convection of viscoplastic fluids in cavities and, if so, under what conditions.Design/methodology/approachThe wall slip was evaluated using a model created for viscoplastic (Bingham) fluids. The coupled conservation equations were solved numerically using the finite element method. Simulations were performed for various parameters: the Rayleigh number, yield number, slip yield number and friction number.FindingsWall slip determines two essential yield stresses: a specific yield stress value beyond which wall slippage is impossible (S_Yc); and a maximum yield stress beyond which convective flow is impossible (Y_c). At low Rayleigh numbers, Y_c is smaller than S_Yc. Hence, the flow attained a stable (conduction) condition before achieving the no-slip condition. However, for more significant Rayleigh numbers Y_c exceeded S_Yc. Thus, the flow will slip at low yield numbers while remaining no-slip at high yield numbers. The possibility of slipping on the wall increases the buoyancy force, facilitating the onset of Rayleigh–Bénard convection.Originality/valueAn essential aspect of this study lies in its comprehensive examination of the effect of slippage on the natural convection flow of viscoplastic materials within a cavity, which has not been previously investigated. This research contributes to a new understanding of the viscoplastic fluid behavior resulting from slipping.

CHARACTERISTICS OF CENTRIFUGAL PUMP FOR PUMPING BINGHAM LIQUID WITH DIFFERENT VALUES OF YIELD STRESSES

General techniques for designing centrifugal pumps are based on calculation features and experimental data on water pumping. On the other hand, pumping non-Newtonian liquids, and Bingham liquids in particular, can change the position of the best efficiency points and change the characteristics. The use of numerical methods allows not only to speed up the search for optimal flow parts, but also to check the possibility of pump operation under extreme operating parameters with different viscosities of a non-Newtonian liquid: from zero viscosity (ideal liquid) to extremely high values, and to create more universal design methods pumps of various types. General techniques for designing centrifugal pumps for pumping non- Newtonian fluids involve adjusting the characteristic depending on the effective viscosity, which for Bingham fluid is calculated from the plastic viscosity. The paper determines the influence of the values of the yield stresses of the Bingham fluid on the characteristics of the centrifugal pump by solving the Reynolds equations, continuity, the turbulence model and the rheological model of the Bingham fluid. It was found that with the same flow rate, the pressure at the pump outlet decreases by no more than 5,1 %. There is a slight shift in the characteristic to the zone of lower flow rate. Thus, the yield stresses have practically no effect on the pressure characteristic of the centrifugal pump. The yield stresses have a sufficient influence on the pump efficiency that they must be considered during the design of the flow part. The efficiency decreases by 10 % when pumping liquid with yield stresses of 100 Pa. A decrease in the efficiency of the pump may be related to the kinematic parameters of the pump and the result of a decrease in pressure distribution on the blade.

Predicting yielding in the pressure-driven flow of a Bingham fluid in a serpentine channel

The use of foams in applications such as enhanced oil recovery and varicose vein sclerotherapy has led to renewed interest in their flow as yield stress fluids. In each application one seeks to determine the ability of a foam to displace another fluid from a tortuous channel. We simulate the pressure-driven flow of a Bingham fluid through a serpentine two-dimensional channel to predict the effects of varying the channel geometry on the size and location of the unyielded regions in which the fluid is either stationary or moving as a plug. We discuss the implications for the effective displacement of blood in varicose vein sclerotherapy.

Morphology Control of Electrospun Brominated Butyl Rubber Microfibrous Membrane.

Brominated butyl rubber (BIIR) is a derivative of butyl rubber, with the advantage of high physical strength, good vibration damping performance, low permeability, aging resistance, weather resistance, etc. However, it is hard to avoid BIIR fiber sticking together due to serious swelling or merging, resulting in few studies on BIIR electrospinning. In this work, brominated butyl rubber membrane (mat) with BIIR microfiber has been prepared by electrospinning. The spinnability of elastomer BIIR has been explored. The factors influencing the morphology of BIIR microfiber membranes have been studied, including solvent, electrospinning parameters, concentration, and the rheological property of electrospinning solution. The optimal parameters for electrospinning BIIR have been obtained. A BIIR membrane with the ideal microfiber morphology has been obtained, which can be peeled from aluminum foil on a collector easily without being broken. Anti-bacterial property, the electrical conductivity of these membranes, and the mechanical properties of these samples were studied. The optimized BIIR electrospinning solution is Bingham fluid. The results of these experiments show that a BIIR membrane can be used in the field of medical prevention, wearable electronics, electronic skin, and in other fields that require antibacterial functional polymer materials.

Motion of Air Bubbles in a Cement Slurry.

The dynamics of air (gas) bubbles in a column of cement slurry is examined numerically. The air injected at the bottom of a laboratory-scale column through a porous distributor plate spatially distributes and migrates as a swarm of bubbles throughout the slurry toward the freeboard. The two-phase system of the cement slurry and the air bubbles is modeled using the conservation equations of mass and linear momentum in the framework of the volume-of-fluid (VOF) approach. The cement slurry is modeled using the Herschel-Bulkley and Bingham fluid models. Results show that the mean Sauter diameter and the mean rise velocity of the bubbles decrease with the gas flow rate. Meanwhile, it is found that the rising of the bubbles is controlled by breakup events, along with relatively weak path instabilities of the bubbles resulting in relatively straight trajectories, independent of the gas flow rate. The extent of the yielded region appears larger for the Herschel-Bulkley model compared to the Bingham fluid model (by approximately 10%).

Analysis of periodic pulsating blood flow of fractional Maxwell power-law fluid in carotid artery with elastic vessel wall

Hemodynamic analysis reveals a highly significant effect on the prevention, diagnosis, and treatment of human vascular diseases. This article goes deeply into the periodic pulsatile blood flow in the carotid artery with an elastic vessel wall. In view of blood rheological experimental data, the constitutive equation of fractional Maxwell power-law fluid with yield stress, which can describe the four characteristics of yield stress, viscoelasticity, shear thinning, and thixotropy is established. Meanwhile, drawing support from the data of pulsatile flow, the finite Fourier series of pressure gradient with a period of 1 s has been proposed. Leading into Hooke’s law can build the fluid-structure coupling boundary condition of blood flow and elastic vessel wall. The numerical solutions are got hold of finite difference method integrated with the newly developed L1-algorithm, and their convergence and stability of which are verified. The axial velocities of blood under different constitutive relationships are compared. The results throw light that other constitutive relationships underestimate the velocity of blood. Furthermore, the flow rate and wall shear stress on different fluid are calculated. It can be concluded that compared with Bingham fluid, the maximum and minimum flow rate/wall shear stress of fractional Maxwell power-law fluid with yield stress increases by 19% and 32%, respectively. The flow rate lags behind the pressure gradient and has time delay effect, on the contrary, the velocity of blood vessel wall is keeping pace with the pressure gradient. The effects of relevant physical parameters on velocity are discussed. In addition, the spatiotemporal distribution of blood flow in cerebral artery and femoral artery are analyzed.

Effect of the Rotation and Inclined Magnetic Field on Peristaltic Slip Flow of a Bingham Fluid in Asymmetric Channel and Porous medium

This essay aims to describe the peristaltic behavior of Bingham's fluid in an asymmetric channel and porous material. The liquid is thought to flow in a porous media and be susceptible to a powerfully inclined magnetic field. The long wavelength dependency and low Reynolds number result in a major simplification of the nonlinear equations. The pressure gradient, pressure rise per wavelength, axial velocity, spin velocity, volume flow rate, and tilted magnetic number are all given specific attention. The findings reveal that rotation, density, permeability, coupling diversity, and non-dimensional wave amplitude all play significant roles in the phenomenon. With rising slip coefficient values and falling magnetic field strengths, permeability, and yield stress coefficients the trapped bolus grows in size

A novel mathematical approach for gravity-driven granular flows in block caving

This study presents a novel mathematical model aimed at elucidating the distinctive behavior observed in the flow of flat-bottom silos. A scheme analogous to the spot model proposed by Bazant is adopted, in which groups of particles move in relation to a static medium. However, we assume that the movement of the particles is driven by the local change in the tensional state instead of the increment of interstitial space through the diffusion of spots. We propose that the tensional state and gravity might induce a driving force with a larger magnitude than the friction exerted at the boundary of the group of mobilized particles. Thus, the dynamics of the flow is controlled by the driving and frictional force. Finally, we have introduced a dimensionless number (Y) corresponding to the ratio of driving to frictional force to characterize the movement of particles. By assuming that frictional force at the interface has a viscous component proportional to the relative speed of the mobilized particles, we have writen an equation analogous to Darcy's law for the flow of a Bingham fluid in a porous medium. The finite element method is utilized to solve the model, and the numerical findings demonstrate a strong correspondence with experimental results achieved in flat-bottom silos featuring one or two openings. Comparatively, the results of the kinematic model are surpassed, with a notable enhancement in the depiction of the velocity field.

Simulation of grout diffusion in fractured rock mass by equivalent seepage lattice elements

There are a large number of discontinuities in underground rock masses with different geometric properties, inducing complex grout diffusion processes. Classical discrete models commonly necessitate fine meshes to explicitly model these discontinuities and result into great computing efforts. In this work, a seepage lattice element model is proposed, which models the fissure seepage by pore seepage in equivalent pipes. We use the new model to study the horizontal grouting cases, considering diffusion as well as solidification processes of Bingham fluid. Some patterns are found: (i) The lattice elements do not need complex discretization which properly capture the grout diffusions processes; (ii) The diffusion of grout will become steady after reaching a specific distance from the injection point where the rock domain full of grout is the diffusion range; (iii) Crack openings, injection pressure and shear strength significantly influence this diffusion range. The proposed method and revealed rules can assist engineers to control the diffusion range and optimize the designs.