non-Newtonian Behaviour (non-newtonian + behaviour)

Distribution by Scientific Domains

Selected Abstracts

Hydromagnetic flow and heat transfer of a conducting Casson fluid in a rectangular channel

Hazem Ali Attia
Abstract The transient hydromagnetic flow of an electrically conducting viscous incompressible non-Newtonian Casson fluid bounded by two parallel non-conducting plates is studied with heat transfer considering the Hall effect. An external uniform magnetic field is applied perpendicular to the plates and the fluid motion is subjected to a pressure gradient in the axial direction. The lower plate is stationary and the upper plate is suddenly set into motion and simultaneously suddenly isothermally heated to a temperature other than the lower plate temperature. Numerical solutions are obtained for the governing momentum and energy equations taking the Joule and viscous dissipations into consideration. The effect of the Hall term and the parameter describing the non-Newtonian behaviour on both the velocity and temperature distributions are studied. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Spinning of protein fibres from blue squat lobster (Cervimunida jhoni) industry by-products

Mario Pérez-Won
Summary The fresh whole crustaceans by-products from blue squat lobster (Cervimunida jhoni) were minced and the protein was solubilised with 0.1 m of NaOH. Then the solution was centrifuged and the supernatant was precipitated using 0.1 m of HCl. The dope was prepared with 4% of protein, solid NaOH and coadjutant (sodium alginate or carragenan). The dope was extruded through the trial-spinning machine and the fibre was formed. The results showed that the best condition of protein extraction was 90 min and pH 12.5 when 58.4% of protein from whole crustacean by-products could be extracted. The protein isolate was obtained at pH 4.0. The best fibres were obtained when the ratios protein/NaOH, and protein/coadjutant were 10:1 and 1:1 respectively. Rheological measurements of all dopes exhibited non-Newtonian behaviour and the experimental data were described by the power law model. The consistency index (k) of the dopes containing carragenan seem to be a parameter to evaluate dope spinnability. [source]

Effect of fat replacers on kefir quality

Bilge Ertekin
Abstract The purpose of the study was to determine the effects of fat replacers on the quality of non-fat kefir. Skim milk fortified with Dairy Lo® (DL) and inulin (INU) was fermented with kefir grains to manufacture kefir. The results of compositional, microbiological, rheological and sensorial analyses were compared with whole kefir (WK) and non-fat kefir (NFK) controls. Results for dry matter, pH and lactic acid ranged between 82.4 and 109.1 g kg,1, 4.26 and 4.40, and 7.0 and 9.2 g L,1, respectively. Acetaldehyde and ethanol contents of samples were between 2.89 and 7.28 mg L,1, and 151.46 and 323.89 mg L,1, respectively. In all samples, Lactobacillus spp., Streptococcus spp. and yeast counts were between 9.1 and 9.9, 9.3 and 9.9, and 5.2 and 5.6 log cfu mL,1, respectively. Kefir samples had non-Newtonian behaviour and pseudoplastic fluid with thixotropy. At the first day, DL had the highest apparent viscosity (3.119 Pa s) while NFK had the lowest value (1.830 Pa s). In the sensory evaluation, odour and taste scores of samples were not different. Dairy Lo® and inulin could be used without any adverse effect for the production of non-fat kefir. Copyright © 2009 Society of Chemical Industry [source]

Separation of a sphere from a flat in the presence of couple stress fluids

Abdallah A. Elsharkawy
Abstract A mathematical model for couple stress fluid is presented to analyse the separation flow of a fully flooded sphere from a flat under the condition of constant load. Assuming the lubricant between the sphere and the flat to contain additives, the couple stress effect, presented by the characteristic length of the additives, has been considered to account for the non-Newtonian behaviour. In addition, the effect of the sphere inertia on accelerating the separation process has been considered. Compared with the Newtonian fluid case, the results of the numerical solution indicated that the separation time increases with increasing the characteristic length of the additives. It was also found that the additive characteristic length has negligible effect on the thickness of the lubricant film at the separation point. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Rheology of polyurethane solutions with different solvents

L de Vasconcelos
Abstract Hard segment hydrogen bonding interactions in a particular polyurethane segmented copolymer have been analysed through a viscometric approach to determine the behaviour of polyurethane solutions with different solvent compositions. Analysis of log,,spversus log c[,] master curves (solely comprising dilute and semidilute regimes) showed that these systems could be differentiated by the slope of the first part of the curve (dilute regime), the characteristic reduced concentration c*[,], and the slope of the second part of the curve (semidilute regime), differences which were related to a possible occurrence of polymer aggregates. Experiments with solutions in the concentrated regime, at different temperatures, were used to relate non-Newtonian behaviour to hydrogen bonding. © 2001 Society of Chemical Industry [source]