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Acoustic streaming phenomena of ultrasound propagation through liquid media was investigated experimentally employing particle image velocimetry (PIV). Parameters associated with the ultrasonic processor of ultrasonic amplitude (i.e., acoustic power) and transducer tip diameter (i.e., surface area), as well as, fluid rheology (i.e., water, glycerol solution and CMC solution), were studied for their effects on overall flow behaviour and fluid velocity. PIV yielded velocity gradient maps, demonstrating the acoustic streaming phenomena of ultrasound and its associated flow behaviour as a function of ultrasonic amplitude and fluid rheology, whereby increasing amplitude allowed for greater penetration of the acoustic-beam through the bulk of the fluid, and increasing fluid rheology yielded the converse effect. Moreover, upon impingement of the acoustic-beam with the base of vessel, vortex formation occurred, yielding a recirculation pattern. The maximum observed fluid velocities for water, glycerol solution and CMC solution were 0.329 m s−1, 0.423 m s−1, and 0.304 m s−1, respectively (large diameter sonotrode tip for an ultrasonic amplitude of 80%). Furthermore, shear rates were attained (maximum values of 24.25 s−1), and Reynolds numbers were determined in order to assess the degree of turbulence as a function of investigated parameters.

The purpose of this research was to evaluate the influence of particle size distribution, pH (5.0–9.0), concentration (1–15 g/100 g.) and temperature (5–60 °C) on the steady shear flow properties of caseinomacropeptide (CMP) aqueous solutions. These measurements were carried out by using a controlled stress rheometer. Flow curves were satisfactorily fitted by the Herschel-Bulkley model. CMP solutions exhibited Newtonian flow dependence, particularly at pH values 5.0–6.0. Non-Newtonian shear thinning behaviour was observed at pH 7.0–9.0. The concentration dependence on viscosity showed two different regimes of viscosity increase (dilute and concentrated). The overlap concentration was 8 g/100 g. The temperature dependent behaviour of CMP solutions fitted to the Arrhenius model regardless pH and concentration, and the calculated activation energy was 20 kJ/mol. The flow behaviour of CMP is explained in terms of peptide-peptide and peptide-water interactions. Based on these results, CMP molecules would form spontaneously micelles at pH > 4.5 in ultrapure water. Fil: Loria, Karina G.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de Luján; Argentina Fil: Aragón, Jimena C.. Universidad Nacional de Luján; Argentina Fil: Torregiani, Sofía M.. Universidad Nacional de Luján; Argentina Fil: Pilosof, Ana Maria Renata. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; Argentina Fil: Farías, María E.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Universidad Nacional de Luján; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina

The influence of concentration on the shear and extensional rheology properties of aqueous solutions of xanthan and guar gums was studied in this work. Shear rheology involved small amplitude oscillatory shear (SAOS), flow curves and transient flow, while the extensional rheology was analyzed using hyperbolic contraction flow. In addition, the mechanical properties during solutions manufacture were monitored in situ through the evolution of torque with processing time by mixing rheometry. The results showed that the hydrocolloids exert a great influence on the process rheokinetics and on the resulting rheological response. SAOS tests showed that the xanthan gum solutions behaved as weak gels, whereas guar gum solutions suggest the presence of entanglement and the formation of a viscoelastic, gel-like structure. All the systems exhibited shear-thinning behaviour. Guar gum solutions obeyed the Cox-Merz rule, with some divergence at high rates for the more concentrated solutions, while the Cox-Merz rule was not followed for xanthan gum in the range of concentration studied. The extensional viscosity exhibited an extensional-thinning behaviour within the strain range used and all solutions were characterized by a high Trouton ratio. Funding details: ceiA3

In this study, a rotating membrane emulsification setup incorporating a 6.1 μm pore diameter SPG membrane was used to produce O/W emulsions of average droplet sizes between 23.4 and 216.6 μm. All emulsions consisted of 10 vol% of sunflower oil or silicone oil stabilised by 1 wt% Tween 20. The transmembrane pressure (0.1–1.8 bar), rotational speeds (100–2000 RPM) annular gap width (5–45 mm), dispersed and continuous phase viscosity were all investigated as to their effect on emulsion droplet size and dispersed phase flux. Modification of the dispersed phase flow properties alters the droplet size with four regions being suggested; a decrease in size (as droplet coalescence is minimised), a plateau (size-stable zone), a gradual increase in size (due to transfer of mass via droplet neck) and then a rapid increase (due to jetting). The importance of Taylor vortices development was seen with larger droplets formed in their absence; typically at low rotational speeds, narrow vessel diameters and more viscous continuous phases. It was concluded that the flow behaviour of each phase requires careful consideration to understand the likely formation mechanism(s) during operation. Across the pressure and viscosity ranges investigated, the dispersed phase flux ranged between 50 and 12,500 Lm −2 h −1 and pore activity was within the range of 0.5–2.7%.

Sheet-bulk metal forming is a new class of sheet forming technology with intended three dimensional material flows as bulk forming process. This new technology usually comprises several traditional forming processes, such as drawing, upsetting, ironing, etc. which exhibits different strain states. The flow behaviours of 2024 aluminium alloy sheet in hot tension and compression were paid attention considering the effect of forming parameters including temperature and initial strain rate in this paper. By regression analysis, the values of deformation activation energy of different processes were calculated. To determined reasonable forming parameters for sheet-bulk metal forming, the power dissipation map and instability map were established based on dynamic materials model theory.

Retardation test, step-shear rate experiments, low-amplitude and large-amplitude dynamic measurements have been combined to study the nonlinear and time-dependent viscosity of dough and shear-induced effects of flow on dough structure. Despite large quantitative differences in linear viscoelastic constants, doughs from different flours or with different water contents display the same type of flow behaviour. Shear-induced structural changes cause flow to shift from a high viscosity steady-state regime to a low viscosity one. The process, irreversible, is responsible for the time-dependent character of dough viscosity and seems to be controlled by the mechanical energy absorbed. Nevertheless, the two steady-state viscosities follow the same shear-thinning flow curve, fitted by a Cross equation with an exponent close to 1; the Newtonian plateau is approached at very low shear rate values. Viscosity data obtained on different doughs yield a unique flow master curve in reduced coordinates. Shear-induced structural changes cause also the linear viscoelastic plateau modulus of dough to decrease; this progressive weakening of the network structure is irreversible and seems governed by the accumulated strain. These characteristics of dough rheology are discussed with reference to the behaviour of concentrated suspensions.

Uniaxial and biaxial tension-torsion tests were carried out on a high strength austenitic steel at room temperature in the strain rate range from 10 −5 to 10 2 s −1 . This material shows a strong dependence of strength on strain rate. The yield loci of the combined tests are described by ellipses. The size and the shape of these ellipses are functions of strain and strain rate. The quasi-static and dynamic tension and tension-torsion behaviour of the austenitic steel is described by Perzyna's constitutive equation. There is good agreement between measured and calculated results if a yield criterion as a function of strain and strain rate, and a formula which contains the dependence of flow stress on strain rate based on thermal activation, are included.