Flow Of Bingham Plastic Fluids Research Articles

Numerical study on the flow of Bingham plastic fluids around an array of cylinders

Numerical study on the flow of Bingham plastic fluids around an array of cylinders

Calculating the entropy generation of a Bingham plastic fluid flow due to a heated rotating disk

We present the numerical study of the flow on a heated rotating disk for Bingham plastic fluid. Thermo-physical properties and viscous dissipation are assumed with the influence of entropy generation. This kind of study has a significant attentiveness in the fields of applied engineering for their increased mathematical advantages. We analyzed the solutions of fluid flow and entropy phenomenon for the Bingham fluid. The similarity solution was firstly presented by von Kármán for Newtonian fluid, it is found to be beneficial for the Bingham plastic fluid by transforming the boundary layer partial differential equations into ordinary differential equations. Shooting method is used to crack the dimensionless ordinary differential equations. The Bingham model is momentous for unlimited high shear rates for this we suggest these numerical data provide accurate description of the Bingham fluid and entropy minimization near a rotating disk. The outcomes exhibits that the azimuthal velocity profiles upsurges for upward values of Bingham fluid, and the similar behavior for tangential radial velocity is perceived. The temperature curve is noted to be enhanced for higher magnitudes of Eckert number and thermal conduction parameter. The soret number and diffusivity coefficient creates increment in concentration curve. The entropy function in the flow system enhances for up surging the inputs of Bingham fluid coefficient and thermophoresis diffusion. The results are locally similar for various parameters. We have also included the comparison analysis with published works.

CFD-based investigation on the flow of Bingham plastic fluids through 90^circ bends

In this paper, CFD-based results are presented on the estimation of losses in bends with validated numerical models for single-phase, incompressible Bingham fluids. Five fittings were investigated: 90^circ bends of different R/D ratios between 1 and 10. Bingham plastic fluids were studied with Hedström numbers in the wide range from 1 to 10^9. Loss coefficients are given as the function of the generalized Reynolds number ({textrm{Re}_textrm{gen}}= 0.1–17 800) and the generalized Dean number ({textrm{De}_textrm{gen}}= 0.1–12 600). The paper presents friction factors as well that were consistent with the literature. It was shown that at low generalized Dean numbers of {textrm{De}_textrm{gen}}< 40, the losses of the bends were caused purely by the wall friction and can be estimated from the {textrm{De}_textrm{gen}}. In a broad range of higher {textrm{Re}_textrm{gen}} and {textrm{De}_textrm{gen}} numbers, the loss coefficients were separated at the basis of the Hedström numbers. This phenomenon was mainly observable in the case of high curvature and was attributed to the flow patterns. Our study investigated this range with the bend of R/D=1 in detail: flow patterns in the bend and at the upstream side of the fitting were examined. An approximating equation and the fitting parameters were also given for loss coefficients.

Onset of Flow Reversal in a Vertical T‐channel: Bingham Fluids

AbstractThe commencement of the flow reversal phenomenon is investigated which occurs in the daughter branch of a vertical T‐channel for the flow of Bingham plastic fluids. The combined influences of the imposed forced flow and buoyancy‐driven flow are analyzed at low Reynolds numbers. The mixed convection flow of a Bingham model fluid is explored for a wide range of conditions in terms of Prandtl number, Richardson number, and Bingham number. The critical Richardson number is strongly influenced by the Prandtl number and the yield stress of the Bingham fluids. The dimensionless pressure is seen to decrease with the critical Richardson number. Also, the fractional flow passing through the main branch exhibits a strong direct dependence on the Richardson number while an opposite relationship with Bingham and Prandtl number is observed.

Forced Convective Flow of Bingham Plastic Fluids in a Branching Channel With the Effect of T-Channel Branching Angle

Abstract This work aims to explore the T-channel momentum and heat transfer characteristics with the combined effect of Bingham plastic fluids (0.01 ≤ Bn ≤ 20) behavior and geometrical variation in terms of branching angle (30 deg ≤ α ≤ 90 deg). The problem has been solved over a wide range of Reynolds number (50 ≤ Re ≤ 300) and Prandtl number (10 ≤ Pr ≤ 50). For the momentum flow, qualitative and quantitative features are analyzed in terms of streamlines, structure of yielded/unyielded regions, shear rate contours, plug width and length variation, and local pressure coefficient. These features have been represented in terms of isotherm patterns, temperature profile, Nusselt number, and its asymptotic value for heat transfer characteristics. The recirculating flows have been presented here in the vicinity of T-junction, which promote mixing and heat transfer. Broadly, the size of this zone bears a positive dependence on Re and α. However, fluid yield stress tends to suppress it. The critical Reynolds and Bingham numbers were found to be strong functions of the pertinent parameters like α. The inclination angle exerts only a weak effect on the yielded/unyielded regions and on the recirculation length of main branch. Results show a strong relationship of the plug width and length with key parameters and branches. The Nusselt number exhibits a positive relationship with α, Bn, and Re but for lower Pr in the T-junction vicinity for both branches. Such length indicates the required optimum channel length for thermal mixing.

Architectural construction using technologies based on knowledge about the flow of Bingham plastic fluids in various pipelines

Currently, such types of engineering work as construction of classic buildings and structures, as well as erection of new ones that have an irregular shape, i.e. curved, arched, elliptical, round and similar surfaces, can be performed using complex technological equipment, such as combined external or internal formwork, the use of shotcrete technology together with the off-formwork construction technologies (3D printers). One of the prerequisites for uniform transportation of media by a concrete pump through pipelines, concrete conveying pipes, and most importantly, their homogeneous distribution by an extruder during layering, is a study based on mathematical modeling and comparative analysis of mathematical models of the flow of Shvedov-Bingham fluids in pipelines of various cross-sections, determining the performance, optimal rheological properties of mortars and concrete liquids. This will allow further control of their fluidity and plastic viscosity during the extrusion process.

Bingham Plastic Fluid Flow between Two Parallel Plates with Temperature Effect

Fluid flow between two parallel plates, both are at rest has been considered in this work. It describes the theoretical analysis of Bingham Plastic fluid model between the plates. The equation of motion, continuity equation and energy equations are solved simultaneously by assuming the plates are of same temperature. A semi analytical solution has been developed and the flow behavior and temperature effect has been discussed and represented with respect to different lubricant parameter.

Native and modified porcine plasma protein as wall materials for microencapsulation of natural essential oils

SummaryPorcine plasma protein (PPP) is of interest as a wall material to encapsulate lemongrass oil, turmeric oil and eucalyptus oil using emulsion technique and freeze drying. The properties of microcapsules were used to evaluate two types of wall material (native porcine plasma protein; NPPP and modified porcine plasma protein; MPPP) at two different ratios of wall material (W) and core material (C) (W:C; 4:1 and 3:1). All NPPP and MPPP emulsions showed Bingham plastic fluid flow behaviours. Moreover, MPPP microcapsules showed lower free oil content on their surface (0.10–0.50%) with higher encapsulation efficiency (91–98%). Fourier‐transform infrared spectroscopy showed the outstanding chemical structure of microcapsules. Furthermore, scanning electron microscopy indicated holes on the surface of microcapsules encapsulated with essential oils. Both PPPs can be used as encapsulation material for natural extract and food additives to improve the food texture and as a biopolymer film to maintain the quality of food products.

Bingham plastic fluid flow model in tape casting of ceramics using two doctor blades – analytical approach

One of the most common processes used in manufacturing of multilayer ceramic packages, multilayer capacitors and large scale integration circuits is tape casting. In this process, the wet tape thickness is one of the single most determining parameters affecting the final properties of the product, and it is therefore of great interest to be able to control it. One way to control the tape thickness is to use a two doctor blade configuration in the tape casting machine. In this case, it becomes important to fix the height of the slurry in front of both doctor blades according to the desired tape thickness and casting speed (belt velocity). In the present work, the flow in both doctor blade regions of a slurry is described with a steady state momentum equation in combination with a Bingham plastic constitutive equation, and this is integrated to a closed form analytical solution for both reservoirs based on the desired wet tape thickness and casting speed. The developed model is used to investigate the impact of different material parameters and machine designs on the required slurry height. The solution is compared with experimental findings from the literature, and good agreement is found.

Steady flow of Bingham plastic fluids past an elliptical cylinder

In the present work, the flow of Bingham plastic fluids past an elliptical cylinder has been investigated numerically elucidating the effect of yield stress and fluid inertia on the momentum transfer characteristics at finite Reynolds numbers for a 100-fold variation in the aspect ratio. The governing differential equations have been solved over wide ranges of Reynolds number (0.01⩽Re⩽40) and Bingham number (0.01⩽Bn⩽100) in the laminar flow regime employing the finite element method. Furthermore, the effect of the aspect ratio (E) of the elliptical cylinder on the detailed flow characteristics has been studied by varying it from E=0.1 to E=10 thereby spanning varying levels of streamlining of the submerged object. In particular, new extensive results on streamline contours, shape and size of yielded/unyielded regions, shear rate profiles, surface pressure distribution and drag coefficient as functions of the Reynolds number, Bingham number and aspect ratio are presented and discussed. The functional dependence of the individual and total drag coefficients on the governing dimensionless parameters, aspect ratio, Reynolds number and Bingham number, is explored. The present results reveal a significant influence of the shape of the cylinder, i.e., aspect ratio on the detailed flow patterns and the overall hydrodynamic flow behavior of elliptical cylinders.

On creeping flow of a Bingham plastic fluid past a square cylinder

In this work, the 2-D creeping flow of Bingham plastic fluids past a cylinder of square cross-section has been studied numerically. The governing differential equations (continuity and momentum) have been solved over a wide range of Bingham number as 1⩽Bn⩽105. Similar to the case of a circular cylinder, three zones of unyielded regions are seen to be present in the vicinity of the submerged cylinder, namely, caps attached to the top and bottom surfaces of the square cylinder, two sectors situated on the lateral sides undergoing rigid-body like motion and the usual far away unyielded regions. The influence of the Bingham number on their size and on the stress (normal and shear components) field in the vicinity of the cylinder is discussed in detail. In addition, the corresponding rate of strain, pressure and stress contours are also presented to facilitate the visualization of the structure of the flow field for scores of values of Bingham number. Also, the present numerical drag results have been correlated with the Bingham number via a simple expression thereby enabling their interpolation for the intermediate values of Bingham numbers.

Explicit equations for laminar flow of Bingham plastic fluids

There are three typical problems encountered in pipe flows, which are: unknown friction factor, unknown flow rate, and unknown diameter problems. A major problem in determining the solution to these flow problems occurs due to the implicit nature of the Darcy–Weisbach friction factor. Though explicit equations for flow of Newtonian fluids and Power Law fluids are available, no such usable equations exist for Bingham plastic fluids. In this paper, explicit equations have been developed for flow of Bingham plastic fluids in the laminar regime. The equations thus developed aim at reducing the computational efforts and the need for using complex and time-consuming iterative solutions of the governing implicit equations for calculating the friction factor, discharge and pipe diameter. An explicit equation for an easier calculation of the critical Reynolds number has also been provided, simplifying the calculation of determining whether the flow is in laminar or turbulent regime.

Effect of Wall Roughness on Laminar Flow of Bingham Plastic Fluids through Microtubes

Miniaturization of traditional devices is in high demand formicro-electro-mechanical systems~MEMS!. Examples includebut are not limited to optics, communication and information sys-tems, fluidics, biotechnology, medicine, automotive, and aero-space. An area of interest in several engineering fields is the con-trol of fluid flow within microchannels and microtubes. Theapplications include, but are not limited to, fields such as vibrationcontrol of structures and systems using small devices, reactors formodification and separation of biological cells, energy systems asa mobile power supply, heat exchangers for micro and macro de-vices, and propulsion engines @1–3#.In recent years, there has been growing attention given to theliquid flow in microchannels in parallel with the development ofminiaturized devices and systems. The understanding of flowcharacteristics, such as velocity distribution and pressure loss isnecessary in design and process control of microfluidic devices.Peng, Peterson, and Wang @4# experimentally studied the flowcharacteristics of water flowing through rectangular microchan-nels having hydraulic diameters of 0.133 to 0.367 mm and heightto width ratios of 0.333 to 1. Their results indicated that the lami-nar flow transition occurred for the range of the Re number be-tween 200 and 700. They also claimed that friction behavior forboth laminar and turbulent flow depart from classical thermofluidcorrelations, and the friction factor is proportional to Re

Explicit calculation of the friction factor in pipeline flow of Bingham plastic fluids: a neural network approach

An artificial neural network (ANN) approach was used in this paper to develop an explicit procedure for calculating the friction factor, f, under both laminar and turbulent flow conditions of Bingham plastic fluids in closed conduits and pipe networks. The procedure aims at reducing the computational efforts as well as eliminating the need for conducting complex and time-consuming iterative solutions of the governing implicit equations for calculating the friction factor, f. The ANN approach involved the establishment of an explicit relationship among the Reynolds number, Re, Hedstrom number, He, and the friction factor, f, under both laminar and turbulent flow conditions. Although, an analytical solution of the governing equation under the laminar flow regime was also feasible (such an equation is also provided in this paper), the ANN model is applicable under both laminar and turbulent flow conditions where the analytical approach will have major limitations (especially when considering the implicit equation that govern the turbulent flow regime).

Bingham plastic fluid flow model for ceramic tape casting

Multilayer ceramic substrates with conductor traces are attracting a great deal of attention for their ability to increase packaging density for large-scale integration circuits. Currently one of the main methods used for the manufacture of flat ceramic packages with precise thickness control and consistency is the tape casting technique. It is crucial that the green tape thickness is controlled precisely and consistently. The fluid mechanics associated with the flow of a ceramic slurry during the tape casting process is analyzed. The flow of the slurry onto the casting surface can be modeled as a two-dimensional fluid flow through a parallel channel. The material of this study is an organic-bonded glass–alumina slurry and is modeled as a Bingham plastic fluid with a yield stress. The proposed model accurately described the fluid flow characteristics of the process, and has good agreement with experimental results.

A Practical Well Control Methodology While Drilling Without Returns

Abstract While drilling in some oil fields of the world, lost circulation may be so severe that normal remedies that might heal the loss zone are not effective. A procedure has been developed to drill "blind" or without returns. The procedure has been refined enough so that stuck drill pipe may be avoided, but the most dangerous aspect of drilling "blind" is the lack of well control. Often when circulation is lost, the well kicks and gas can flow into the wellbore due to drastic reduction in hydrostatic pressure. Furthermore, normal well control operations are ineffective. The procedure generally involves pumping a viscous slug of waterbased gel mud into the annulus and this column of mud is called a "mudcap." This approach depends on whether the lost zone is above or below a gas zone and either approach effectively limits the amount of fluid that can be used. In order to properly place a mudcap, a better understanding of the relationship between the fluid rheological properties, column height, and the initial shut-in casing pressure is required. In this respect, no quick field procedure has been developed to help rigsite personnel to control these types of wells. A set of charts have been constructed to aid field personnel in blowout prevention, when they are confronted with a gas kick occurring while drilling without returns. This situation is common in many oil fields especially in Middle East and North Africa. The set of charts is based on the slot flow approximation for Bingham fluids. Two sets of charts are developed: one for the case in which pipe is in the hole and the other when the casing is opened. Each of the charts represents a different annular configuration. These charts make life easier for rig personnel especially in a very stressful situation, and this type of pre-planning should help to avoid costly mistakes in judgment. Introduction Solutions for equations describing axial annular flow of Newtonian fluids can be determined directly. However, direct methods for solving annular flow equations for more complex rheological models, such as Bingham-Plastic and Power-Law, usually result in unwieldy expressions. To avoid this the slot flow approximation was developed. This method equates the geometry of an annulus to that of a narrow slot. Depending upon the geometric parameters used in the narrow slot approximation and the degree of accuracy required, some sort of correction for the curvature of annulus may be needed. Therefore, a suitable expression for the Newtonian curvature correction factor must be developed. Using the same correction factor as for Newtonian fluids, a slot flow approximation of the axial annular flow of Bingham-Plastic fluids should be relatively accurate. The primary purpose of this paper was to develop relations that describe the annular flow of Bingham-Plastic fluids and the pressure gradient necessary to initiate flow. With an expression that relates pressure gradient to the Bingham Plastic yield point, a set of practical charts was developed.

Finite element analysis of the duct flow of Bingham plastic fluids: an application of the variational inequality

SUMMARY The duct flow of Bingham plastic fluids is analysed with the variational inequality-based finite element method. The problem of tracking the yield surface is solvable through the regularization technique which can be easily incorporated into the existing finite element code. The existence theorem of this method was established through the theory of variational inequalities. A small positive constant is added to the second shear rate invariant, resulting in an apparent viscosity of finite magnitude in the unyielding plug zone. This makes the minimization of the non-differential variational integral possible. In order to achieve convergence at small regularization parameter, a zero-order continuation is employed. It is also shown that a fine tessellation of the flow domain is necessary for tracking the yield surfaces unambiguously. Two classes of duct flow, namely axial flows in eccentric annuli and in an L-shaped duct, were investigated. In both cases it was easy to show the presence of the mobile plugs around the duct centres from the axial velocity profiles; however, the stagnant plugs at the narrow side in eccentric annuli with large eccentricity and near the apex of right-angled corners in an L-shaped duct could only be identified from the calculation of the distributions of the second shear rate or shear stress invariant. # 1997 John Wiley & Sons, Ltd.

Characterization of flow regime in concentric annuli and pipes for yield-pseudoplastic fluids

This paper presents an analysis of the laminar-turbulent transition for flow of yield-pseudoplastic fluids in pipes and concentric annuli. The yield-pseudoplastic rheology is represented by the three-parameter Robertson-Stiff model. A modified Reynolds number is developed based on an equivalent diameter including characteristic parameters of the flow situations under consideration. Using the literature data, Hanks' theory of laminar flow stability is reanalyzed in comparison with other correlations. On account of the generality of Hanks' stability criterion and its experimentally proven success to some extent, it is used herein to calculate critical values of the modified Reynolds number. Numerical results are presented in terms of the dimensionless rheological parameters and the annulus aspect ratio. Further, it is shown that constant critical value of Hanks' stability parameter (Kmc = 404) does not necessarily apply to non-Newtonian fluids. This fact is demonstrated for pipe flow of Bingham plastic fluids.

Characteristics of a Pulsating Bingham Plastic Fluid Flow in a Curved Pipe. Experimental and Numerical Study.

The fully developed pulsating laminar flows of an incompressible Bingham plastic fluid through a pipe of circular cross section coiled in a circle were investigated experimentaly and numerically. The flow fields were characterized by the Dean number De, Hedstrom number He, the Womersley number Wo and the curvature ratio δ. The friction factors were measured experimentaly for various volumetric ratio in the case of Wo=4. The calculations were carried out for a fixed He. The flow patterns and the axial velocity profiles were required in the calculations. It was clarified that the effects of the curvature of the pipes appeared easily for Newtonians compared with the plastic fluids. That is, the values of the amplitudes of the friction factor λac of the plastic fluid were smaller than that of Newtonians for a range of high Dean number, especially in the case of lower curvature ratio. In the calculations, it was found in the case of a plastic fluids that, in the axial velocity distributions a typical plug flow area appeared near the outer side of the vent in all of a period, and that the strength of the secondary flows were greater than that of Newtonians especially within the period the volumetric rates increased.

Characteristics of a Palsating Bingham Plastic Fluid Flow in a Curved Pipe. Analysis Using Power-Law Model.

Pulsating laminar flows of a purely viscous non-Newtonian fluid in a curved pipe of circular cross section in the high Dean number region were investigated analytically by using boundary layer approximations. The governing equations were formulated for a Power-Law fluid. The momentum integral approach and Pohlhausen's approximate method were used to analyze the flow in some detail, and the governing equations were solved by the successive approximation. In the case of steady flow, the present theory was in good agreement with previous experimental data, and the friction factor becomes greater as the pseudoplasticity index n decreases. In the case of Palsatile flow, the phase lag of the mean sectional velocity from the wave of pressure gradient, Γ, and the amplitude of the friction factor, λ^^∼ac, diminishes with increasing Dean number, and Γ diminishes with increasing n. The phase lag Γ and the amplitude of the friction factor λ^^∼ac derived in this work are in qualitative agreement with available experimental data.