non-Newtonian Fluid Characteristics Research Articles

Evaluation of pectin extracted enzymatically from cocoa (Theobroma cacao L.) pod husks

La presente investigacion tuvo como proposito evaluar elrendimiento y las caracteristicas de la pectina extraida enzimaticamente a partir de la cascara, pericarpio del fruto de cacao (Theobroma cacao L.); para ello, se realizo un diseno de tipo unifactorial, con 4 niveles de tratamiento, variando la concentracion de complejo enzimatico comercial Viscozyme L., de la marca Novozyme®. La pectina obtenida fue caracterizada, de acuerdo a la metodologia planteada por Owens et al. 1952. Se elaboro un producto comercial tipo conserva (mermelada), donde se comparo la pectina obtenida enzimaticamente, con pectina comercial de alto y bajo metoxilo; en ambos casos fue evaluada la viscosidad aparente del fluido obtenido. Como resultados, se obtuvo mayor rendimiento de extraccion de pectina promedio (13,0±0,53%), utilizando la mayor concentracion de complejo enzimatico (82,9 μL/100g cascara), presentando diferencias significativas con los demas tratamientos (p<0,05); el porcentaje de metoxilo (ME) fue de 1,58±0,01%, el peso equivalente (PE) 5091,4±77,6 mg/meq; la acidez libre (AL) 0,20±0,01meq/g; el grado de esterificacion (GE) 72±0,1% y el porcentaje de acido anhidridogalacturonico (AAG) 12,5±1,0%. Con respecto al producto comercial, se observaron caracteristicas reologicas de un fluido no Newtoniano pseudoplastico, con una viscosidad aparente maxima de 6043,7 mPa.s y minima de 1741,3 mPa.s, al aumentar la fuerza del torque, presentando una menor capacidad viscosante que la pectina comercial. De acuerdo a los resultados obtenidos, se demostro que existe la oportunidad de obtener pectinas a partir de residuos del sector cacaotero, utilizando enzimas comerciales, con posibles usos en la industria alimentaria.

Hemodynamics for the Vascular Surgeon

Knowledge of the pathophysiology of peripheral vascular disorders is necessary for vascular surgeons to identify disease and develop appropriate treatment plans. Hemodynamics is the branch of physiology dealing with the forces involved in the circulation of the blood. Principles of hemodynamics and blood flow physiology are the basis for noninvasive vascular testing methods that are used for diagnosis and objective assessment of disease severity. Clinical decision making should incorporate anatomic, functional, and physiologic considerations. This review focuses on understanding clinical applications of fundamental hemodynamic principles as they apply in normal and pathologic states. Key concepts are presented in the context of common clinical scenarios. This review contains 18 figures, and 43 references. Key words: ambulatory venous hypertension; collateral development; fluid energy; Hagen-Poiseuille equation; laminar and nonlaminar (turbulent) flow; newtonian and nonnewtonian fluid characteristics; pressure and flow relationships; pressure, resistance, and regulation of perfusion; pulse wave propagation; venous capacitance; venous pump; wall tension, wall, shear, and the law of LaPlace

Synthesis and Characterization of Halogen-Free Flame Retardant Two-Component Waterborne Polyurethane by Different Modification

Diethyl N,N-bis(2-hydroxyethyl)aminomethylphosphonate and halogen-free poly(phosphate) as reactive halogen-free flame retardants and soft or hard segment modifiers were compounded to waterborne polyurethane polyols after being emulsified and then were mixed with isophorone diisocyanate and dimethylolpropionic acid to synthesize two-component waterborne polyurethanes having fire resistance. As a result, the rheological behavior of prepolymer emulsion really accords with characteristics of non-Newtonian fluid. The highest limit oxygen index is 27.8% in two-component system modified by hard segment, which was 527.5% than the clean; meanwhile, one is 28.6% in another two-component system, which was 627.6% than the clean. The hardness, solvent resistance, and mechanical property in both of the two-component systems are outstanding. Adding flame retardant can effectively improve the flame resistance, tensile strength, and pot-life of two-component waterborne polyurethanes, especially in being modified by soft s...

A novel investigation of a micropolar fluid characterized by nonlinear constitutive diffusion model in boundary layer flow and heat transfer.

The rheological and heat-conduction constitutive models of micropolar fluids (MFs), which are important non-Newtonian fluids, have been, until now, characterized by simple linear expressions, and as a consequence, the non-Newtonian performance of such fluids could not be effectively captured. Here, we establish the novel nonlinear constitutive models of a micropolar fluid and apply them to boundary layer flow and heat transfer problems. The nonlinear power law function of angular velocity is represented in the new models by employing generalized "n-diffusion theory," which has successfully described the characteristics of non-Newtonian fluids, such as shear-thinning and shear-thickening fluids. These novel models may offer a new approach to the theoretical understanding of shear-thinning behavior and anomalous heat transfer caused by the collective micro-rotation effects in a MF with shear flow according to recent experiments. The nonlinear similarity equations with a power law form are derived and the approximate analytical solutions are obtained by the homotopy analysis method, which is in good agreement with the numerical solutions. The results indicate that non-Newtonian behaviors involving a MF depend substantially on the power exponent n and the modified material parameter [Formula: see text] introduced by us. Furthermore, the relations of the engineering interest parameters, including local boundary layer thickness, local skin friction, and Nusselt number are found to be fitted by a quadratic polynomial to n with high precision, which enables the extraction of the rapid predictions from a complex nonlinear boundary-layer transport system.

Study on Heat Transfer of Non-Newtonian Power Law Fluid in Pipes with Different Cross Sections

In industrial applications, most of fluids have non-Newtonian fluid characteristics. It is of great significance to the economic development and energy consumption reduction to study the heat transfer of non-Newtonian power law fluid. In this paper, the heat transfer of non-Newtonian power law fluid in pipes with different cross sections are studied. The mathematical model and physical model of the non-Newtonian fluid are briefly introduced first, and the physical model is divided by the structured mesh. Then the numerical simulation of the laminar heat transfer of non-Newtonian fluid in different cross sections is carried out. On the basis of discussing the distribution of temperature field, many parameters which have influenced on the temperature field and the heat transfer is analyzed in this paper, such as tube shape, the power-law index (n) the Peclet number (Pe) and so on. The results show that the heat transfer characteristics of non-Newtonian fluid are related to the parameters we mentioned.

MATHEMATICAL MODELS DESCRIBE RHEOLOGICAL BEHAVIOR PF RAPESEED OILS

Ponte Academic JournalApr 2017, Volume 73, Issue 4 MATHEMATICAL MODELS DESCRIBE RHEOLOGICAL BEHAVIOR PF RAPESEED OILS Author(s): Ioana StanciuJ. Ponte - Apr 2017 - Volume 73 - Issue 4 doi: 10.21506/j.ponte.2017.4.58 Abstract:This article presents a study of log dynamic viscosity variation with log shear rate for rapeseed oils obtained from different stages of processing. The for each of the 5 types of oils studied was determined the dynamic viscosity by changing the shear rate from 3.3 to 120 s-1 and temperature from 40oC to 90oC with Haake VT 550 viscometer equipped with HV1 sensor. Analyzing the results, it was noticed a decrease in log dynamic viscosity for the log shear rate, as increase for all tested oils and for all temperatures at which determinations were performed. The decreasing log dynamic viscosity with increasing log shear rate shows that these oils have characteristics of non-Newtonian pseudoplastic fluids. The proposed mathematical equations describe well the rheological behavior of the 5 types of rapeseed oils as correlation coefficients are close to unity Download full text:Check if you have access through your login credentials or your institution Username Password

On rheological characteristics of non-Newtonian nanofluids in the material forming process

In this paper, the material forming process (such as that of the functionally graded materials) of adding nanoparticles into non-Newtonian fluids is considered. By adding nanoparticles to a non-Newtonian fluid, a new non-Newtonian fluid is created. Thus, the rheological characteristics of the original fluid matrix have been changed. This research attempts to consider the influence of the rheological characteristics combined with the Brownian diffusion, and the thermophoresis diffusion, the distribution of nano-sized particles, the heat transfer, and the pressure drop on the process of material formation. The configuration of material treatment process is an H-height horizontal parallel plate channel with laminar forced convection nanofluids-based non-Newtonian fluids flowing through. The channel is separated by three different boundary conditions: heating, cooling, and isolated, to simulate the melting, the freezing, and the flowing processes of materials in liquid form. The non-Newtonian behaviour of nanofluids is described by the power-law model. To highlight the rheological factors of power-law nanofluids which are not the same as those of the base non-Newtonian fluids, they are assumed to vary with the quantity of the added nanoparticles in the fluid matrix, that is to say, both the consistency coefficient $$m$$ and the power-law index $$n$$ are considered as functions of particle loading parameter $$\phi$$ . Two sets of different functions of consistency coefficient $$m$$ and power-law index $$n$$ are used and compared in the later calculation. Method of finite element is adopted to solve the coupled momentum, energy and concentration equations, and conquer the difficulties arsing in the iteration of calculation. It is found that whether the rheological factors of non-Newtonian nanofluids are considered changeable or not would lead to very different results of the mass transfer. Also, as the parameter $$N_{\text{T}}$$ (depicting the thermophoresis diffusion) increases, both temperature and concentration profiles rise, while volume fraction of particles and temperature both fall as $$N_{\text{B}}$$ number (presenting the Brownian diffusion) increases. Furthermore, when two models are compared, different rheological models may possess different change rule of power-law index, but in both rheological models, the diversification of power-law index is so large that it cannot be ignored in calculation. Above all, the detailed information of velocity, temperature, and pressure drop obtained by rheological models highlights the necessity of studying the impact of rheological characteristics of non-Newtonian fluids in elaborate industrial requirements.

Dynamic characteristics of Non Newtonian fluid Squeeze film damper

The fluids which do not follow linear relationship between rate of strain and shear stress are termed as non-Newtonian fluid. The non-Newtonian fluids are usually categorized as those in which shear stress depends on the rates of shear only, fluids for which relation between shear stress and rate of shear depends on time and the visco inelastic fluids which possess both elastic and viscous properties. It is quite difficult to provide a single constitutive relation that can be used to define a non-Newtonian fluid due to a great diversity found in its physical structure. Non-Newtonian fluids can present a complex rheological behaviour involving shear-thinning, viscoelastic or thixotropic effects. The rheological characterization of complex fluids is an important issue in many areas. The paper analyses the damping and stiffness characteristics of non-Newtonian fluids (waxy crude oil) used in squeeze film dampers using the available literature for viscosity characterization. Damping and stiffness characteristic will be evaluated as a function of shear strain rate, temperature and percentage wax concentration etc.

Numerical Study on the Heat Transfer Performance of Non-Newtonian Fluid Flow in a Manifold Microchannel Heat Sink

For the past few decades, with the rapid development of micro-electro-mechanical- systems (MEMS) and Lab-on-a-chip, the electronic devices continue to be miniaturized and highly integrated. Meanwhile, on account of miniaturization and integration, it essentially brings in high heat flux, which makes heat transfer enhancement to be a hot topic in these fields. With the heat flux rising, the traditional cooling method becomes unable to meet the demands of heat removal in the highly integrated devices. As one of the most promising heat exchange technologies with high efficiency, the microchannel heat sinks (MHS) was proposed. For a long time, modifying the microchannel structures is a promising way to enhance heat transfer, such as using manifold microchannel (MMC). Except modifying the microchannel structures, changing mediums in MHS could also contribute to better flow distribution and heat transfer performance. This paper concentrates on the synergy effect of non-Newtonian fluids and MMC heat sink on heat transfer enhancement. Numerical simulation of the non-Newtonian fluid in MMC is carried out in order to obtain its flow and heat transfer performance. The power-law non-Newtonian fluids are chosen as the cooling medium while water is a reference medium. The traditional microchannel (TMC) heat sink as an important reference model aims at evaluating the performance of the MMC heat sink through analyzing temperature distribution, power-law non-Newtonian fluids and so on. Numerical simulations are conducted for Newtonian and non-Newtonian fluid at a fixed heat flux on the heating wall. It is found that, in MMC heat sink, the non-Newtonian fluid characteristics could result in a significant variation in heat transfer coefficient with increasing inlet velocity. Moreover, the introduction of pseudoplastic fluid (shear-thinning fluid) leads to an outstanding increase of heat transfer performance comparing with those of Newtonian and dilatant fluids (shear-thickening fluid). Keywords: Manifold microchannel heat sinks; non-Newtonian fluids; heat transfer performance;

Unsteady flow of a dusty Bingham fluid through a porous medium in a circular pipe

A time-varying flow through a porous medium of a dusty viscous incompressible Bingham fluid in a circular pipe is studied. A constant pressure gradient is applied in the axial direction, whereas the particle phase is assumed to behave as a viscous fluid. The effect of the medium porosity, the non-Newtonian fluid characteristics, and the particle phase viscosity on the transient behavior of the velocity, volumetric flow rates, and skin friction coefficients of both the fluid and particle phases is investigated. A numerical solution is obtained for the governing nonlinear momentum equations by using the method of finite differences.

Experimental study on high-pressure rheology of water/crude oil emulsion in the presence of methane

ABSTRACTThe crude oil is in most cases accompanied with water and natural gas. For this reason, it is important to understand the rheology of the oil emulsion. There are already many works relating to rheology of the oil/water emulsion. However, studies on high-pressure rheology of water/crude oil emulsion in the presence of CH4 are rare. In this work, light crude oil with characteristics of high wax content, which is typical in Northwest China, was studied. The rheology of water/crude oil emulsion in the presence of CH4 under various conditions were fully studied. The results show that the crude oil emulsion showed obvious characteristics of non-Newtonian fluid at a lower temperature. Before water fraction reached a certain limit, the viscosity increases with the increase of water fraction, when water fraction reaches and exceeds the limit the emulsion viscosity drops with the increase of water fraction. The shear stress–shear rate curves become similar as the increase of temperature, indicating the decreasing effect of temperature on the relation between shear stress and shear rate. When the pressure reaches 8 MPa, the shear stress measured with CH4 in the system surpasses that measured without CH4. At higher pressure, CH4 shows obvious influence on the rheology.

Multiple solutions in MHD flow and heat transfer of Sisko fluid containing nanoparticles migration with a convective boundary condition: Critical points

The motivation behind the present analysis is to focus on magneto-hydrodynamic flow and heat transfer characteristics of non-Newtonian fluid (Sisko fluid) past a permeable nonlinear shrinking sheet utilizing nanoparticles involving convective boundary condition. The non-homogenous nanofluid transport model considering the effect of Brownian motion, thermophoresis, suction/injection and no nanoparticle flux at the sheet with convective boundary condition has been solved numerically by the RKF45 method with shooting technique. Critical points for various pertinent parameters are evaluated in this study. The dual solutions (both first and second solutions) are captured in certain range of material constant $ (n_{c}< n < \infty)$ , mass transfer parameter $ (s_{c} < s < \infty)$ and shrinking parameter $ (\chi_{c} < \chi < 0)$ . For both the branches (upper and lower branch), the rate of heat transfer is an increasing function of the power-law index, Prandtl number and Biot number, whereas it is a decreasing function of the material constant and thermophoresis parameter.

PIV Experimental Study on the Characteristics of Non-Newtonian Fluid in Wavy-walled Tubes for Pulsatile Flow

PIV Experimental Study on the Characteristics of Non-Newtonian Fluid in Wavy-walled Tubes for Pulsatile Flow

Ultraprecision Machining of Si&lt;sub&gt;3&lt;/sub&gt;N&lt;sub&gt;4&lt;/sub&gt; Ceramics with Shear-Thickening Polishing

Shear-thickening polishing (STP) technology was used on ultraprecision machining of Si3N4 ceramics. The STP slurry with diamond abrasives was prepared for STP process and its rheological property was studied. The polishing performance of Si3N4 ceramics with STP was analyzed. Results show that STP slurry with diamond abrasives exhibits non-Newtonian power-law fluid characteristics with shear-thickening effect. As using STP slurry with abrasive particle size of 0.2 μm, the material removal rate changed from 4.22 to 4.05 μm/h after 60 mins ́ polishing; and decreased from 3.88 to 3.75 μm/h after 120 mins ́ polishing. The average surface roughness reduced from Ra 107.2 to Ra 6.5 nm after 120 mins ́ polishing.

The Study of Flow Characteristics of Newtonian and Power-Law Non-Newtonian Fluids by Dam-Break Flow Model

The study aims to investigate the flow characteristics of Newtonian and power-law non Newtonian fluids by using the dam-break of finite extent problem. Analytical and numerical studies are carried out to clarify the flow characteristics. In the analytical study, shallow flow equations are used to derive the characteristic in the viscous flow region for both the Newtonian and power-law non-Newtonian fluids. A numerical model based on the Volume of Fluids (VOF) method with higher order numerical scheme is used to verify the analytical findings. The study derived the flow characteristics based on the propagation of front position and the attenuation of flow depth at the dam upstream boundary.

Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge.

Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.

시추용 머드혼합탱크의 비뉴턴 유체 모델에 대한 교반성능의 수치해석적 연구

ABSTRACT Non-Newtonian fluid mechanics takes charge of an important role in the oil industries. Especially in the oil well drilling process, the drilling fluid such as mud keeps the drill bit cool and clean during drilling, with suspending drill cuttings and lubricating a drill bit. The purpose of this study is to examine the effect of fluid mud rheological properties to predict different characteristics of non-Newtonian fluid in the mud mixing tank on offshore drilling platforms. In this paper, ANSYS fluent package was used for the simulation to solve the hydrodynamic force and to evaluate mud mixing time. Prediction of the power consumption and the pumping effectiveness has been presented with different operating fluid models as Newtonian and non-Newtonian fluid. The comparison between Newtonain mud model and non-Newtonian mud model is confirmed by the CFD simulation method of drilling mud mixing tank. The results present useful information for the design of the drilling mud mixing tanks and provide some guidance on the use of CFD tool for such non-Newtonian fluid flow.

Laminar flow of non-Newtonian shear-thinning fluids in a T-channel

Flow characteristics of non-Newtonian power-law fluids in a right-angled horizontal T-channel are studied in the laminar regime. In particular, the two-dimensional numerical computations are performed using Ansys Fluent for the following range of physical parameters: Reynolds number (Re)=5–200 and power-law index (n)=0.2–1 (covering shear-thinning, n<1 and Newtonian, n=1 fluids). The flow fields have been explained by streamline contours. The engineering parameters such as wake/recirculation length, critical Reynolds number for the onset of flow separation and the variation of viscosity along the lower wall of side branch are calculated for the above range of settings by using constant density and non-Newtonian power-law viscosity model. The results showed that for a particular n, the length of recirculation zone increases in the side branch with increasing Re. Also, it increases with decreasing n for a fixed Re. The critical Reynolds number for the onset of flow separation decreases with decreasing n. A simple wake-length correlation is also established at different values of Re and n for the range of parameters.

Chitosan Phase Change Fiber Rheology and its Performance Study

Optional viscosity average molecular weight of chitosan 3 × 105, the nanophase change microcapsules were mixed in the preparation chitosan spinning dope. Viscometer was used to measure the rheological properties of blend spinning fluid, using infrared spectroscopy,scanning electron microscope (SEM) and the interactions between the studies of phase change fiber surface microstructure. The results show that, blend spinning fluid is generally the basic characteristics of non-Newtonian fluid, with concentration of spinning solution, viscosity increases; temperature rise, viscosity decreased; prolonged standing, viscosity decreased. Chemical changes occurred between chitosan and microencapsulated phase change,no new chemical bonds, for a simple physical blending. By scanning electron microscope, along with the increase in the amount of phase change nanomicrocapsule, fiber surface is obvious.

Ion slip effect on a steady flow through a circular pipe of a dusty conducting Oldroyd 8-constant fluid

In this paper, a steady magnetohydrodynamic (MHD) flow of a dusty incompressible electrically conducting Oldroyd 8-constant fluid through a circular pipe is examined with considering the ion slip effect. A constant pressure gradient in the axial direction and an external uniform magnetic field in the perpendicular direction are applied. A numerical solution is obtained for the governing nonlinear momentum equations by using finite differences. The effect of the ion slip, the non-Newtonian fluid characteristics, and the particle-phase viscosity on the velocity, volumetric flow rates, and skin friction coefficients of both the fluid and particle phases is reported.