We discuss the linear and nonlinear rheology of concentrated microscale emulsions, amorphous disordered solids composed of repulsive and deformable soft colloidal spheres. Based on recent results from simulation and theory, we derive quantitative predictions for the dependences of the elastic shear modulus and the yield stress on the droplet volume fraction. The remarkable agreement with experi...

The main objective of this study was to investigate the rheology of mixed primary and secondary sludge and its dependency on solid content and temperature. Results of this study showed that the temperature and solid concentration are critical parameters affecting the mixed sludge rheology. It was found that the yield stress increases with an increase in the sludge solid content and decreases wi...

We study dense colloidal crystals under oscillatory shear using a confocal microscope. At large strains the crystals yield and the suspensions form shear bands. The pure harmonic response exhibited by the suspension rules out the applicability of nonlinear rheology models typically used to describe shear banding in other types of complex fluids. Instead, we show that a model based on the coexis...

A fundamental study of the stability of hydrogen peroxide-based gels, thickened using cross-linked polyacrylic acid polymers, will be presented. Recent systematic experiments will demonstrate that excellent long-term stability of such gels can be achieved. The study evaluates different types of crosslinked polyacrylic acid polymers (as well as an associative acrylic polymer), several commercial...

Blood is a two-phase suspension of formed elements (i.e., red blood cells [RBCs], white blood cells [WBCs], platelets) suspended in an aqueous solution of organic molecules, proteins, and salts called plasma. The apparent viscosity of blood depends on the existing shear forces (i.e., blood behaves as a non-Newtonian fluid) and is determined by hematocrit, plasma viscosity, RBC aggregation, and ...

Success of a drilling, workover or completion fluid can be directly attributed to its viscosity at the shear rate of interest. In practice, fluids are subjected to a wide range of shear rates; therefore, a thorough understanding of fluid rheology and the impact of shear is necessary to optimize fluid design. Ideally, high viscosity is desirable only under low shear rate conditions, and should d...

The paper describes an experimental study concerning the mechanical properties of bacterial biofilms formed from the early dental plaque colonizer Streptoccocus mutans and pond water biofilms. Experiments reported in this paper demonstrate that both types of biofilms exhibit mechanical behavior similar to that of rheological fluids. The time-dependent properties of both biofilms have been model...

Several surfactant molecules self-assemble in solution to form long, flexible wormlike micelles which get entangled with each other, leading to viscoelastic gel phases. We discuss our recent work on the rheology of such a gel formed in the dilute aqueous solutions of a surfactant CTAT. In the linear rheology regime, the storage modulus G(ω) and loss modulus G(ω) have been measured over a wide f...

It would clearly be pointless in this lecture either to attempt to list all the papers that have been published on a vast variety of foodstuffs, nor even selecting only a fcw, to describe in detail to a Budapest audience, the apparatus that is commonly used for testing a few of the principal products that have been intensively studied. Under Professor TELEGDy-Kov~.(Ts, pioneer work has been and...

We review the viscous and viscoelastic behaviours of concentrated food emulsions and plant food suspensions. Special attention has been given to the influence that food processing exerts on the rheological characteristics of the abovementioned foodstuffs.