Flow Behavior Index Values Research Articles

Numerical Study of Laminar Fully Developed Non-Newtonian Liquid Flow in Rough Circular Microchannel

The present study aims to unveil the characteristics of fully developed laminar, incompressible, pressure driven non-Newtonian liquid flow in rough circular microchannels. In the present analysis Gaussian isotropic roughness distribution in circular microchannel is considered. The effect of varying surface wall roughness and flow behavior index has been studied numerically for both the pseudo plastic and dilatant fluids. It is found out that while increasing the relative roughness for a particular flow behavior index, the frictional resistance to flow in the microchannel increases and the effect is more pronounced in the case of pseudo plastic fluids. In the case of a pseudo plastic liquid flow for a constant relative surface wall roughness, on decreasing the value of flow behavior index below 1, the frictional resistance to the flow in the channel increases. While in the case of dilatant fluids with increasing the value of flow behavior index from 1 and above for a constant relative surface wall roughness the frictional resistance to the flow in the channel decreases.

Transient pressure analysis for vertical wells with spherical power-law flow

Heavy oil is considered nowadays as one of the unconventional reservoirs of main interest in the oil industry. Some of them display non-Newtonian pseudoplastic behavior which mathematical modeling differs from the conventional case and, therefore, the flow regimes display some particular behaviors.Fracturing fluids, foams, some fluids for Enhanced Oil Recovery (EOR) and drilling muds can also fall into this category. The spherical/hemispherical flow mainly caused by partial completion/penetration deserves a particular treatment for pseudoplastic flow. A single research for this case was found in the literature to introduce only its mathematical model.
 The pressure and pressure derivative behavior of spherical/hemispherical flow behavior of a slightly compressible, non-Newtonian power-law fluid (pseudoplastic) is studied in this work and conventional and Tiab’s Direct Synthesis (TDS) methodologies are extended for well test interpretation purposes. For pseudoplastic spherical/ hemispherical flow, the slope of the pressure derivative is no longer -½, besides it changes with the value of flow behavior index n, which indicates that the interpretation of pressure data for the dealt systems through the use of traditional methods should not be accurate. New Equations are introduced to estimate spherical/ hemispherical permeability and spherical/hemispherical skin factor for the systems under consideration. The Equations were successfully verified by its application to synthetic cases.

Mathematical approach for two component modeling of salep–starch mixtures using central composite rotatable design: Part I. Physicochemical and steady shear properties

A 2-factor-5-level central composite rotatable design (CCRD) of response surface methodology (RSM) was used to model linear, interaction and quadratic effects of some processing variables (salep and each starch type, the composition variables) on the response variables; physicochemical characteristics (pH, brix and turbidity) and steady shear rheological properties (apparent viscosity η, consistency coefficient K, shear stress σ and flow-behavior index n) of salep–starch mixtures (SSM); namely, salep–corn starch mixture (SCSM), salep–wheat starch mixture (SWSM) and salep–potato starch mixture (SPSM). The linear, interaction and quadratic effects of the processing variables were also modeled to develop predictive models for the tested properties to optimize the effect of these variables (salep and each starch type) using ridge analysis involved with RSM. It was concluded that salep and all starch types increased the apparent viscosity (η), shear stress (σ) and consistency coefficient (K) values; decreased the flow-behavior index (n) values of SSM samples. Salep was observed to vastly increase the viscosity of mixture samples when mixed with corn, wheat or potato starches. However, potato starch exhibited very different performance as compared to the other starches in terms of the physicochemical and steady shear rheological properties. The ridge analysis used to optimize these effects revealed that maximum η (0.84, 0.46 and 1.38 Pa s), and K (16.64, 6.48 and 28.86 Pa sn) values for the SCSM, SWSM and SPSM samples, respectively would occur at salep = 0.54% and starch = 2.83% w/w.

Fully-developed thermal transport in combined electroosmotic and pressure driven flow of power-law fluids in microchannels

Thermally fully-developed heat transfer has been analyzed for combined electroosmotic and pressure driven flow of power-law fluid in a microchannel. Analytical expressions for transport parameters are presented in terms of the flow behavior index, the length scale ratio (ratio of Debye length to half channel height), dimensionless pressure gradient, and Joule heating parameter (ratio of Joule heating to surface heat flux). Closed form solutions are obtained for some specific values of the flow behavior index, while numerical solutions are presented for general cases. The results show that the temperature variation across the channel increases with increasing the pressure gradient. To reduce the length scale ratio is found to decrease the temperature variation, particularly for shear-thinning fluids. To increase the Joule heating parameter is to enlarge the temperature variation in the channel, especially for shear-thickening fluids. The Nusselt number can be increased by decreasing the length scale ratio due to the electroosmotic effect. Also, the Nusselt number increases with decreasing the values of flow behavior index and dimensionless pressure gradient.

Composition and characterization of simulated putrescible garbage

Abstract The composition and characterization of liquidised garbage (LG) during liquidisation process were carried out to access various properties, viz., moisture, organics, ash, elemental composition, suspension stability, flow characteristics, higher heating value (HHV), glucose and total organic carbon (TOC) for getting preliminary information about liquidisation as a pre-treatment process for anaerobic digestion of simulated garbage (SG). Minimum moisture and maximum organic content were found as 750 and 850 g kg −1 , respectively. From elemental analysis, C/N ratio obtained was suitable for the growth of microbes. The HHV of dried solid phase for LG at 393 K was higher than that of mechanically ground garbage (MEC). The LG was regarded as a pseudo plastic liquid from values of flow behaviour index obtained. The amount of glucose was found to be decreased during liquidisation process. The amount of TOC in both solid and liquid phase of LG was more as compared to MEC.

Simplex lattice mixture design approach on the rheological behavior of glucomannan based salep-honey drink mixtures: An optimization study based on the sensory properties

The rheological properties of salep drink sweetened with different honeys were measured using a controlled-stress rheometer. Mixture design experiments were used to study the effect of interactions among pine, flower and highland honeys on the rheological properties of salep-honey drink mixture (SHDM) samples. In addition, product optimization was carried out using the ridge analysis to determine the optimum mixture proportions based on sensory properties of SHDM samples. Flower honey was the component showing the highest effect on the consistency coefficient values of SHDM samples. The preference of panelists was more prominent for the SHDM samples including the higher concentrations of highland honey with respect to odour and overall preference parameters. Optimum values of pine, flower and highland honeys in the mixture were found to be 0–85%, 0–40% and 15–100%, respectively, with respect to sensory properties. In addition, ridge analysis results revealed that the SHDM should include 65% highland honey, 35% pine honey and no flower honey to obtain the maximum overall preference score (7.24). The consistency coefficient and flow behavior index values of the sample to get maximum overall preference score (7.24) were predicted to be 3.650 Pa sn and 0.435, respectively.

Effect of incubation temperature and caseinates on the rheological behaviour of Kefir

The effect of incubation temperature and the addition of caseinates on the rheological behaviour of kefir was studied by using a pneumatic tube viscometer of novel design. The results indicated that the incubation time increased as the incubation temperature was reduced and the casein concentration was increased. Kefir samples incubated at 25°C showed the highest values of viscosity, while the samples incubated at 30°C exhibited the lowest viscosity. The addition of caseinates caused the viscosity of the samples to increase and their flow behaviour index values to decrease. Kefir samples incubated at 30°C exhibited the highest flow behaviour index values.

Rheological and dielectric properties of different gold nanoparticle sizes

BackgroundGold nanoparticles (GNPs) have found themselves useful for diagnostic, drug delivery and biomedicine applications, but one of the important concerns is about their safety in clinical applications. Nanoparticle size has been shown to be an extremely important parameter affecting the nanoparticle uptake and cellular internalization. The rheological properties assume to be very important as it affects the pressure drop and hence the pumping power when nano-fluids are circulated in a closed loop. The rheological and dielectric properties have not been documented and identified before. The aim of the present study was to investigate the rheology and the dielectric properties of different GNPs sizes in aqueous solution.Methods10, 20 and 50 nm GNPs (Product MKN-Au, CANADA) was used in this study. The rheological parameters were viscosity, torque, shear stress, shear rate, plastic viscosity, yield stress, consistency index, and activation energy. These rheological parameters were measured using Brookfield LVDV-III Programmable rheometer supplied with temperature bath and controlled by a computer.ResultsThe shear stress and shear rate of GNPs have shown a linear relationship and GNPs exhibited Newtonian behaviour. The GNPs with larger particle size (50 nm) exhibited more viscosity than those with smaller particle sizes (10 and 20 nm). Viscosity decreased with increasing the temperature for all the examined GNP sizes. The flow behaviour index (n) values were nearly ≤ 1 for all examined GNP sizes. Dielectric data indicated that the GNPs have strong dielectric dispersion in the frequency range of 20-100 kHz. The conductivity and relaxation time decreased with increasing the GNP size.ConclusionsThis study indicates that the GNP size has considerable influence on the viscosity of GNPs. The strong dielectric dispersion was GNP size dependent. The decrease in relaxation time might be attributed to increase in the localized charges distribution within the medium confirmed by the conductivity data. This study suggests that further experiments are required to be done after the administration of GNPs through different routes in rats in vivo.

호밀가루의 레올로지 특성분석

Rheological properties of cereals such as rye are great important for the design of die for extrusion and the development of models for extrusion process. Therefore, this study was carried out to analyze the rheological properties according to moisture content of rye flour and extrusion temperature. Rheological properties of rye flour were investigated by using a capillary rheometer for moisture content of three levels (30, 35, 40%) and extrusion temperature of three levels (120, 130, 140℃). Determination coefficients for the relationship between apparent shear stress (τap) and apparent shear velocity (ϒap) were relatively high in the range of 0.973 ~ 0.997 under each extrusion condition. The values of consistency index (K) was decreased with increasing moisture content and extrusion temperature. However, the value of flow behavior index (n) presented the highest value at moisture content of 35%, but it was not affected by extrusion temperature.

Rheological behaviour and physicochemical properties of kefir with honey

The effect of the flower and pine honey on the rheological behavior of kefir was investigated. Major aim was to produce a new functional fermented milk beverages with honey. Soluble solid was changed from 6.37 to 25.28; refractive index values were between 1.342 and 1.374; pH was changed from 4.04 to 4.65 and color values, L of samples were determined as 63.10–73.18. The rheological properties of the samples were determined using a controlled stress rheometer. It was observed that an empirical power-law model was suitable to describe the rheological behavior of kefir with honey with correlation coefficients (R 2) between 0.991 and 0.96. The apparent viscosity of the kefir with honey decreased with increasing shear rate. Flow behavior index (n) and consistency index (K) values for the kefir with honey ranged from 0.3711 to 0.4691, 130 to 204 mPa s, respectively. The model kefir with honey was found to exhibit non-Newtonian behavior.

Electroosmotic flow of power-law fluids at high zeta potentials

In this paper, a mathematical model for electroosmotic flow of power-law fluids in a rectangular microchannel at high zeta potential is analyzed. The electric double layer (EDL) potential distribution is considered without Debye Huckel linear approximation. Numerical solution is obtained to analyze the fluid flow behavior. Parametric studies are conducted to assess the variation of shear stress, viscosity and volumetric flow rates of various values of flow behavior index ( n). Computed results are used to explicate the possibility of using a relatively pseudoplastic fluid inside microchannel to obtain higher volumetric flow rates.

Characterization of the Dextran Produced by Leuconostoc mesenteroides from Date Fruit Extract

In the present study, the production of dextran from date extract and sucrose as carbon sources by the bacterium Leuconostoc mesenteroides NRRL B512 (f) was investigated. In comparison to blue dextran (Mw≈2000 Da), dextran molecular weight was reduced (Mw2000 KDa). Flow behavior indices of dextran solutions from date extracts were investigated and rheological parameters were evaluated at concentrations of 1.5, 2.5, 5, together with 10% total solids at 25˚C using a Brookfield rotational viscometer as well as a cone and plate geometry. The experimental results followed the power law model for the best fit and the values of flow behavior index (n) were less than unity (0.49 .93) at all concentrations, revealing the shear thinning nature of the produced dextran. Furthermore, dependence of apparent viscosity on concentration was confirmed using the power law model.

Rheological Properties of Waxy Rice Starch-Gum Mixtures in Steady and Dynamic Shear

The effects of guar gum (GG) and xanthan gum (XG) at different concentrations (0, 0.2, 0.4, and 0.6% w/w) on the rheological properties of Korean waxy rice starch (WRS) pastes were evaluated under both steady and dynamic shear conditions. The flow properties of WRS-gum mixtures were determined from the rheological parameters of the power law model. The addition of GG and XG to WRS resulted in an increase in the apparent viscosity (η<SUB>a,100</SUB>) and consistency index (K) values obtained from power law model. The flow behavior index (n) values of the WRS-XG mixtures decreased with an increase in gum concentration while there was only a marginal difference between n values for the WRS-GG mixtures. Dynamic moduli (G', G

Viscometric Behavior of Reconstituted Tomato Concentrate

The rheological properties of tomato concen- trates produced by hot and cold break have been exten- sively studied by many authors. Only a few studies, however, focus specifically with the rheology of reconsti- tuted concentrates from tomato powders. In this study, the rheological properties of reconstituted tomato concentrate from lyophilized freeze-dried tomato juice were evaluated using rotational viscometer at temperatures 20°C, 30°C, 40°C, 50°C, and 60°C and at concentrations of 9.7%, 12.9%, 20.5%, and 26.8% total soluble solids. Using power law model, both flow behavior index (n) and consistency coefficient (k) were determined. The calculated values of flow behavior index (n) were less than unity (0.03-0.28) at all temperatures and concentrations indicating the shear- thinning characteristic of the concentrate. The effect of temperature and concentration on the consistency coeffi- cient (k) was studied. Positive correlation between k in the range of 1.57 and 38.33 Pa s n and inverse absolute temperature (1/T) has been shown by Arrhenius model. Additionally, linear correlation between consistency coeffi- cient (k) and concentration (C )w as determined. The activation energies were found in the range of 3.63 and 7.36 kJ/mol K depending on concentration. The results of this study might be useful to improve the design of processing operations dealing with tomato powder reconstitution.

Rheological and Sensory Properties of Spray Dried Pekmez Mixtures with Wheat Starch-Gum

Pekmez, known also as grape molasses, was spray dried in the laboratory-type pilot drying unit to obtain pekmez powder. The flow characteristics of diluted pekmez powder (DPP), wheat starch (WS), and some hydrocolloids (locust bean gum, LBG; gum tragacanth, GT, and guar gum, GG) systems in double- or triple-mixed combinations were studied. The empirical power law model fitted the apparent viscosity-rotational speed data. DPP-gum and WS-gum mixed solutions exhibited a shear-thinning behaviour at 21°C with flow behaviour index (n) values of 0.88 ≤ n ≤ 0.94 and 0.17 ≤ n ≤ 0.32, respectively. WS-gum mixed solutions showed high shear-thinning behaviour with the highest consistency index (k = 49.93–214.24 Pa sn). However, DPP-WS and DPP-WS-gum mixed solutions at the same temperature exhibited the shear-thickening behaviour with flow behaviour index (n) values of 1.02 ≤ n ≤ 1.07.

Steady and Dynamic Shear Rheology of Fucoidan‐Buckwheat Starch Mixtures

AbstractRheological properties of fucoidan (F) and buckwheat starch (B) mixtures (3% or 6%) at different blending ratios of fucoidans (0, 0.1, 0.2, 0.5 and 1.0%) were investigated in steady and dynamic shear. Steady shear viscosity measurement revealed that aqueous pastes of the BF blends (3%, w/v) had a pseudoplastic and shear‐thinning behavior with flow behavior index (n) values of 0.61–0.68. The substitution of starch with fucoidan polymers significantly lowered the apparent viscosities compared with the pure starch paste and, when mixed with less than 0.5% of fucoidan, the viscosities of the pastes were even lower than those of the starch pastes at the corresponding starch concentrations. According to dynamic viscoelastic measurement performed at 6% total carbohydrate concentration, buckwheat starch mixtures behaved like weak gels and the BF blends containing less than 0.5% fucoidan had considerably lower storage (G') and loss (G') moduli than the starch paste at the corresponding starch concentrations. However, the magnitude of G' increased with fucoidan concentrations over 0.5%, suggesting that a concentration of fucoidans &gt; 0.5% might enhance the formations of three‐dimensional networks and crosslinking of the starch samples, probably because of the mutual exclusion between starch and fucoidan polymers through the phase separation process. This study indicates that it is possible to obtain the BF blends having various rheological properties by changing the concentration of fucoidan polymers.

Stability and rheological behaviour of salad dressing obtained with whey and different combinations of stabilizers

SummaryIn this work the stability and the rheological behaviour of salad dressing containing ‘Minas Frescal’ whey cheese was studied. The salad dressing was stabilised by xanthan gum (XG), propylene glycol alginate (PGA) and carboxymethylcellulose (CMC). All samples were stable for a period of 4 months. The rheological model of Ostwald‐de‐Waelle (Power‐Law) was used in order to fit the data and to obtain the rheological parameters of flow behaviour index (n), consistency coefficient and apparent viscosity (ηap). All formulations showed a pseudoplastic behaviour and the PGA contributed to increase the values of flow behaviour index. Consistency coefficient was similarly affected by XG and PGA fractions. Apparent viscosity was highly influenced by the hydrocolloid CMC, with higher values of apparent viscosity in the proportion of 0.25/0.25/0.5% (PGA/XG/CMC). Hydrocolloid association (ternary mixtures) was statistically significant, resulting in an increase of K and ηap parameters. The results show that salad dressing with whey as aqueous phase and stabilised by a ternary combination of XG, PGA and CMC can be a technological alternative to the food industry.

Modelling of rheological behaviour of pummelo juice concentrates using master-curve

The rheological behaviour of freeze-dried-concentrated pummelo juice was modelled to investigate the effects of temperature and concentration on its fluid type and viscosity using a rotational viscometer at shear rates ranging from 1 to 400 s −1. The effect of concentration measured by its total soluble solids content resulted in the juice concentrates behaving towards shear thinning or pseudoplastic behaviour with flow behaviour index values, n < 1. Temperature increase from 6 to 75 °C produced a reversing effect of the shear thinning behaviour from the increase of n values at all three investigated concentrations, 20, 30 and 50 °Brix. The consistency coefficient decreases with temperature but increases with total soluble solid contents. Modelling the rheological behaviour of pummelo juice concentrates using the master-curve yielded results over a range of temperature to overlap on a single line, which allows generalisation of flow behaviour and characteristics. The master-curve plots confirmed that the juice viscosity and pseudoplasticity increase with concentration with high regression coefficients, R 2 > 0.98.

Rheological Properties of Tomato Concentrate

Rheological properties of tomato concentrate were evaluated using a wide-gap rotational viscometer (Brookfield Engineering Laboratories: Model LVDV-II) at different temperatures of 20, 30, 40, 50, and 60oC, at concentration of 18, 12.18 and 8.04 % total solids, and at appropriate shear rate(1-100 RPM). The power law model was fitted to the experimental results. The values of flow behaviour index (n) were found less than unity (0.23 to 0.82) at all the temperature and the concentration indicating shear-thinning (pseudoplasticity) behaviour of the concentrate. The correlation between the observed consistency coefficient ranging from 0.09 to 65.87 Pa.sn and the inverse absolute temperature has been exhibited by Arrhenius model. Consistency coefficient increased exponentially with increase in the concentration. Statistical model was used for prediction of the consistency coefficient as a function of temperature and concentration which showed a good agreement (r2=0.99) between experimental and theoretical values. The magnitude of activation energy were found to be in the range of 8.6 to 14.08 kJ/mol.K.

Mathematical Models for Prediction of Rheological Parameters of Pineapple Juice

Rheological characteristics of pineapple juice have been investigated and rheological parameters were evaluated using rotational viscometer at temperatures 20, 30 and 40*C at concentration 26.77, 18.99 and 14 % total solids. The experimental results followed the power law model for the best fit and the values of flow behaviour index (n) was less than unity (0.08 to 0.87) at all temperatures and concentrations indicating the shear thinning (pseudoplasticity) nature of juice. An obvious correlation between consistency coefficient in the range of 0.1 - 37.16 Pa.sn and inverse absolute temperature has been exhibited by Arrhenius model. The Power equation indicated that the consistency coefficient increased non-linearly with an increase in concentration. Mathematical models were developed for prediction of the consistency coefficient as a function of temperature and concentration. A good agreement was observed between experimental and theoretical values of the consistency coefficient predicted by models. The magnitude of activation energy was found to be in the range of 3.67 to 4.62 kJ/mol.K.