Non-Newtonian Drops Spreading on a Flat Surface

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
A. Dechelette ◽  
P. E. Sojka ◽  
C. R. Wassgren
Keyword(s):  
Flat Surface ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Viscous Forces ◽  
Model Predictions ◽  
Newtonian Liquids ◽  
Experimental Values ◽  
Behavior Index

The objective of this study is to develop a computational model that accurately describes the dynamic behavior of a non-Newtonian power-law film formed after a drop impinges on a flat surface. The non-Newtonian drop deposition and spreading process is described by a model based on one developed for Newtonian liquids. The effects of variations in non-Newtonian liquid rheological parameters, such as Ren (the non-Newtonian Reynolds number), n (the flow behavior index), and We (the Weber number), are studied in detail. Results show that a reduction in the viscous forces results in enhanced spreading of the film followed by a more rapid recession. An increase in surface tension results in reduced spreading of the film, followed by a more rapid recession. Model predictions of film diameter as a function of time were larger than corresponding experimental values obtained as part of this study. However, the discrepancy never exceeded 21%, demonstrating that the model accurately predicts the phenomena of interest. This comparison also shows that the results are in best agreement for large non-Newtonian Reynolds numbers and small non-Newtonian Ohnesorge numbers (We/Ren).

Impact of Non-Newtonian Drops on Pharmaceutical Tablet Surfaces

2006 ◽  
Author(s):  
Alexis Dechelette ◽  
Paul E. Sojka ◽  
Carl R. Wassgren
Keyword(s):  
Flat Surface ◽  
Flow Behavior ◽  
Consistency Index ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Viscous Forces ◽  
Pharmaceutical Tablet ◽  
Fluid Behavior ◽  
The One ◽  
Behavior Index

This study discusses the spreading of a non-Newtonian, power-law, film formed after a drop impinges on a flat surface (i.e., a pharmaceutical tablet). Non-Newtonian drop spreading is described by a model based on the one of Roisman et al. [2002]. The effects of variations in non-Newtonian liquid rheological parameters m (the consistency index) and n (the fluid behavior index) are shown to be significant. In either case, changes leading to a reduction in viscous forces result in enhanced spreading of the film, followed by more rapid recession. Both are expected. Of interest is the observation that an increase in consistency index can be compensated for by a reduction in flow behavior index since the sensitivity of film recession to a change in n is larger than that to variations in m.

Shear Rate Corrections for Herschel-Bulkley Fluids in Couette Geometry

2008 ◽  
Vol 18 (3) ◽  
pp. 34482-1-34482-11 ◽  
Author(s):  
Vassilios C. Kelessidis ◽  
Roberto Maglione
Keyword(s):  
Flow Behavior ◽  
Flow Equation ◽  
Oil Field ◽  
Rheological Parameters ◽  
Concentric Cylinder ◽  
Flow Behavior Index ◽  
Shear Rates ◽  
Power Law Fluids ◽  
Good Agreement ◽  
Behavior Index

AbstractA methodology is presented to invert the flow equation of a Herschel-Bulkley fluid in Couette concentric cylinder geometry, thus enabling simultaneous computation of the true shear rates, γ̇HB, and of the three Herschel-Bulkley rheological parameters. The errors made when these rheological parameters are computed using Newtonian shear rates, γ̇N, as it is normal practice by research and industry personnel, can then be estimated. Quantification of these errors has been performed using narrow gap viscometer data from literature, with most of them taken with oil-field rheometers. The results indicate that significant differences exist between the yield stress and the flow behavior index computed using γ̇HB versus the parameters obtained using γ̇N and this is an outcome of the higher γ̇HB values. Predicted true shear rates and rheological parameters are in very good agreement with results reported by other investigators, who have followed different approaches to invert the flow equation, both for yield-pseudoplastic and power-law fluids.

Rheological Properties of Butia Pulp

2006 ◽  
Vol 2 (1) ◽  
Author(s):  
Charles Windson Isidoro Haminiuk ◽  
Maria-Rita Sierakowski ◽  
Giselle Maria Maciel ◽  
José Raniere Mazile Bezerra Vidal ◽  
Ivanise Guilherme Branco ◽  
...  
Keyword(s):  
Yield Stress ◽  
Apparent Viscosity ◽  
Good Description ◽  
Flow Behavior ◽  
Rheological Parameters ◽  
Concentric Cylinder ◽  
Flow Behavior Index ◽  
Different Temperatures ◽  
Stress Flow ◽  
Behavior Index

Rheological parameters of Butia pulp were determined at different temperatures using a concentric cylinder Haake Rotovisco rheometer, model RV-20, with measurement system ZA-30. Butia pulp was found to exhibit non-Newtonian, pseudoplastic behavior at all temperatures and the rheological parameters were adequately described by the Herschel-Bulkley model. Yield stress, flow behavior index, and consistency coefficient were significantly affected by temperature. The yield stress decreased exponentially with process temperature and ranged between 36.60 and 21.70 Pa. Apparent viscosity calculated through the Herschel-Bulkley model decreased with an increase in temperature. The Arrhenius model gave a good description of temperature effect on apparent viscosity of the pulp.

scholarly journals Effect of grasshopper (Sphenarium purpurascens Charpentier) paste addition on rheological behavior of Mole Poblano

2021 ◽  
Author(s):  
Eliza Guadalupe Arcos-Estrada ◽  
Mayra Díaz-Ramírez ◽  
Judith Jiménez-Guzmán ◽  
Erika Berenice León-Espinosa ◽  
Mariano García-Garibay ◽  
...  
Keyword(s):  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Design Methodology ◽  
Water Retention ◽  
Flow Behavior ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Emulsifying Capacity ◽  
Behavior Index

Objective: Analyze the effect of grasshopper (Sphenarium purpurascens Charpentier) paste addition on the rheological behavior of Mole Poblano (MP) and its relation with the technological properties of the grasshopper paste. Design/methodology/approach: The addition of grasshopper paste was done at different proportions as follows: T0= 0% of grasshopper paste (GP) and 100% of mole Poblano (MP); T10=10% GP and 90% MP; T15=15% GP and 85% MP, T20=20% GP and 80% MP, T25=25% GP and 75 % MP, T30=30% GP and 70% MP. Water retention and emulsifying capacity of grasshopper paste were evaluated. Density, kinematic and apparent viscosity, and rheological behavior were analyzed at 25ºC; rheological parameters (consistency index (k) and flow behavior index (n)) were calculated by performing a regression analysis to adjust the graphs to a power-law model. Findings/conclusion: Grasshopper paste had higher emulsifying capability than water retention capability.  Apparent viscosity of all formulations decreased as shear rate increased, so all mixtures of GP and MP demonstrated No-Newtonian behavior and pseudoplastic performance. Index consistency increased as GP content increased, these results are related with protein content because GP had a good emulsifying capability. Limitations on study/implications: More studies about the characterization of the proteins of GP and their interaction with other components are required.

Effects of Greek Pomegranate Extracts in the Antioxidant Properties and Storage Stability of Kefir

2019 ◽  
Vol 15 (4) ◽  
pp. 437-441 ◽  
Author(s):  
Vasiliki Lagouri ◽  
Georgia Dimitreli ◽  
Aikatarini Kouvatsi
Keyword(s):  
Antioxidant Activity ◽  
Dairy Products ◽  
Storage Time ◽  
Storage Stability ◽  
Flow Behavior ◽  
Antioxidant Properties ◽  
Flow Behavior Index ◽  
Ph Values ◽  
Dpph Activity ◽  
Behavior Index

Background: Oxidation reactions are known to shorten the shelf life and cause damage to foods rich in fat, such as dairy products. One way to limit oxidation and increase the shelf life of fermented dairy products is to use natural antioxidants. The aim of this study was to examine the effect of adding pomegranate extracts in the antioxidant properties, rheological characteristics and the storage stability of the fermented product of kefir. Methods: The Pomegranate Juice (PGJ) and Peel Extracts (PGPE) (5%, 10% w/v) were added to kefir and the antioxidant properties were evaluated by using the methods of radical scavenging activity (DPPH) and Ferric Reducing Antioxidant Power Activity (FRAP). Spectrophotometric and instrumental methods were used to determine the Total Phenols (TPs), pH values, viscosity and flow behavioral index values of enriched with pomegranate kefir samples. The same properties were tested when kefir samples stored at 4°C for 7, 14, 21 and 28 days. Results: The addition of PGJ and PGPE results in an increase in the antioxidant activity (DPPH, FRAP) and total phenol content (TPs) of kefir samples. Increasing the concentration of the added PGJ and PGPE, results in an increase in the TP content and the DPPH activity of kefir. As far as the storage time is concerned, the results showed an increase in the amount of TP at 7th day and a reduction in the DPPH activity in the 14th day of storage. In contrary to the DPPH method, the increase in storage time has resulted in a reduction in antioxidant activity by the FRAP method. The addition of PGJ and PGPE in kefir results in a decrease in pH values while the pH of kefir samples increased during storage at 4°C for 28 days. The addition of PGJ and PGPE to kefir samples results to a decrease in viscosity and an increase in the flow behavior index. Increasing storage time results in increased flow behavior index of kefir samples. Conclusion: The addition of PGJ and PGPE increased the antioxidant activity and total phenols of the kefir product and preserved its properties during the total storage time of 28 days at 4°C.

Electroosmotic Flow of Power-Law Fluids in a Slit Microchannel

2009 ◽  
Author(s):  
Cunlu Zhao ◽  
Chun Yang
Keyword(s):  
Shear Stress ◽  
Double Layer ◽  
Power Law ◽  
Dynamic Viscosity ◽  
Electroosmotic Flow ◽  
Flow Behavior ◽  
Flow Behavior Index ◽  
Power Law Fluids ◽  
Hyperbolic Cosine ◽  
Behavior Index

Electroosmotic flow of power-law fluids in a slit channel is analyzed. The governing equations including the linearized Poisson–Boltzmann equation, the Cauchy momentum equation and the continuity equation are solved to seek analytical expressions for the shear stress, dynamic viscosity and velocity distributions. Specifically, exact solutions of the velocity distributions are explicitly found for several special values of the flow behavior index. Furthermore, with the implementation of an approximate scheme for the hyperbolic cosine function, approximate solutions of the velocity distributions are obtained. In addition, a mathematical expression for the average electroosmotic velocity is derived for large values of the dimensionless electrokinetic parameter, κH, in a fashion similar to the Smoluchowski equation. Hence, a generalized Smoluchowski velocity is introduced by taking into account contributions due to the finite thickness of the electric double layer and the flow behavior index of power-law fluids. Finally, calculations are performed to examine the effects of κH, flow behavior index, double layer thickness, and applied electric field on the shear stress, dynamic viscosity, velocity distribution, and average velocity/flow rate of the electroosmotic flow of power-law fluids.

scholarly journals Estimation of Rheological Properties of Ice Cream Unfrozen Liquid Phase by FT-NIR Spectroscopy

1970 ◽  
Vol 66 (2) ◽  
Author(s):  
Florina A. SILAGHI ◽  
Alessandro GIUNCHI ◽  
Angelo FABBRI ◽  
Luigi RAGNI
Keyword(s):  
Liquid Phase ◽  
Rheological Properties ◽  
Powder Mixture ◽  
Goodness Of Fit ◽  
Flow Behavior ◽  
Nir Spectroscopy ◽  
Ice Cream ◽  
Rheological Parameters ◽  
Good Prediction ◽  
Flow Behavior Index

The control of ice cream powder mixture production is carried out evaluating the ice cream liquid phase. The present study was conduced on ice cream and unfrozen liquid phase in order to indirectly evaluate the rheological properties by measuring the powder mixture. The calibration set was formed by samples with different percentage of thickeners, maintaining constant the concentration of the other remaining compounds. After the NIR acquisitions the powders were mixed with warm milk, blended and than settled in order to obtain the unfrozen liquid phase needed for the rheological measurements. For each recipe three batches were prepared. The flow curves were evaluated by using the Ostwald de Waele’s equation and the goodness of fit was evaluated by the R2, which was above 0.95. Predictive models of rheological parameters were set up by means of PLS regressions in order to predict the consistency coefficient (K) and the flow behavior index (n) from spectral acquisitions. High correlation of calibration was found for both parameters and NIR spectra obtaining R2 of 0.884 for K and 0.874 for n. The good prediction of the models encourages applying them to reduce significantly the time of the powder mixing control during production.

scholarly journals COMPORTAMENTO REOLÓGICO DE EXTRATOS DE GRÃOS, FARINHA INTEGRAL E ISOLADO PROTÉICO DE SOJA

2003 ◽  
Vol 21 (2) ◽  
Author(s):  
ROSANE DA SILVA RODRIGUES ◽  
ÂNGELA MARIA GOZZO ◽  
ROBERTO HERMÍNIO MORETTI
Keyword(s):  
Newtonian Fluid ◽  
Soy Protein ◽  
Apparent Viscosity ◽  
Flow Behavior ◽  
Total Solid ◽  
Soy Flour ◽  
Soluble Solids ◽  
Rheological Parameters ◽  
Flow Behavior Index ◽  
Isolated Soy Protein

Estudou-se o comportamento reológico de extratos elaborados com grãos, farinha integral e isolado protéico de soja. Extratos com 3% de proteína foram obtidos de grãos de soja (em equipamento conhecido como “vaca mecânica”), de farinha integral e de isolado protéico (por dissolução em água) e pasteurizados a 74±2°C por 15 seg. Os parâmetros reológicos estudados foram o coeficiente de consistência, o índice de comportamento do fluxo e a viscosidade aparente. Foram determinados, também, sólidos totais, proteínas, lipídios, cinzas, fibra bruta, carboidratos e índice de sedimentação (AOAC, 1995). Verificou-se que a viscosidade aparente, a 4 e 25°C, do extrato obtido de grãos de soja (fluido nãonewtoniano com comportamento pseudoplástico) foi maior que a do extrato da farinha (fluido não-newtoniano com comportamento pseudoplástico a 4°C e dilatante a 25°C) e do isolado (fluido newtoniano). O maior índice de sedimentação constatado no extrato de farinha integral e o baixo teor de sólidos solúveis no isolado protéico foram determinantes, entre outros fatores, no comportamento reológico verificado. AbstractRHEOLOGICAL BEHAVIOR OF SOYMILK, WHOLE SOY FLOUR AND SOY ISOLATED PROTEIN The rheological properties of extracts elaborated with soybeans, whole soy flour and isolated protein were studied. Extracts with 3% of protein were obtained from soybeans (in a equipment called “mechanic cow”), whole soy flour and isolated soy protein (by dissolution in water) and pasteurized at 74±2°C for 15 seg. The rheological parameters studied were the flow behavior index, consistency coefficient and apparent viscosity. Total solid, proteins, lipids, ashes, brute fiber, carbohydrates and sedimentation index (AOAC, 1995) was also determined. The apparent viscosity, at 4 and 25°C, of the extract obtained from soybeans (non-newtonian fluid with pseudoplastic behavior), was greater than the one of whole soy flour extract (nonnewtonian fluid with pseudoplastic behavior at 4°C and dilatant at 25°C) and of the isolated soy protein extract (Newtonian fluid). The highest sedimentation index verified in the whole soy flour extract and the low content of soluble solids in the extract of isolated soy protein defined, among others factors, the rheological behavior verified.

Flow Speed Measurement and Rheometry by Pulsed Neutron Activation

1989 ◽  
Vol 111 (3) ◽  
pp. 337-341 ◽  
Author(s):  
K. G. A. Porges ◽  
S. A. Cox ◽  
C. Herzenberg ◽  
C. Kampschoer
Keyword(s):  
Laminar Flow ◽  
Neutron Activation ◽  
Flow Behavior ◽  
Industrial Plant ◽  
Rheological Parameters ◽  
Slurry Flow ◽  
Flow Behavior Index ◽  
Processing Scheme ◽  
Wide Range ◽  
Pulsed Neutron

Pulsed Neutron Activation (PNA) is a means of noninvasive flow velocity measurement based on tagging the flowing medium with a short-lived radioactivity. Previous work with salt or dye-tagging showed poor accuracy in turbulent and failed in laminar flow when conventional data processing was used. However, use of a data acquisition and processing scheme that is based on tag dispersion modelling can produce absolute values over a wide range of flow speeds and regimes with high accuracy. For non-Newtonian/laminar flow, rheological information can also be obtained. The inherently non-intrusive nature of PNA tagging makes this scheme available for slurry measurements. The performance of PNA in slurry flow at up to 60 percent solid content was compared to full-flow diversion and weighing. Errors ranged from less than 0.2 percent at high Reynolds’ numbers to about 2 percent for paste flow. Rheological parameters (yield shear stress or flow behavior index) could be determined with an accuracy that compared to that of a spindle viscometer with grab-samples. The PNA scheme thus offers a unique means of studying slurry flow in a dedicated laboratory facility, or of providing calibration for other flowmeters in an industrial plant through temporary installation by a team of expert consultants.

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