Topic
Rheometer
About: Rheometer is a research topic. Over the lifetime, 5759 publications have been published within this topic receiving 125849 citations.
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TL;DR: The viscometer was used to carry out a series of preliminary studies in which platelet-rich plasma was subjected to continuous and pulsatile shear stress at 37 degrees C and shear-induced platelet aggregation was significantly greater in response to pulsatile versus continuous shearing except at the lowest applied stress.
43 citations
TL;DR: In this paper, the low-rate falling-plate extensional rheometer experiments by Sridhar and coworkers on a mobile polymer solution were simulated using a free-surface finite-element code which accounts for gravity and surface tension.
Abstract: The low-rate falling-plate extensional rheometer experiments by Sridhar and coworkers on a mobile polymer solution were simulated using a free-surface finite-element code which accounts for gravity and surface tension. There is a reverse flow near the plates which is caused by the interaction between gravitational and surface tension forces, causing a delay in the development of the uniform cylindrical column and a difference between the local and imposed extension rates during the early stages of the experiment.
43 citations
TL;DR: In this article, Bender element technique was used to measure the shear wave responses in both drying and wetting conditions, and step function was used as excitation, and determination of a first arrival time was identified and consistently used for all the measurements.
Abstract: Shear wave propagation in soil is a physical phenomenon and has been used widely for monitoring and seismic property assessment in geotechnical engineering. Shear wave velocity Vs and small-strain shear modulus G0 are the key parameters in defining material response to various dynamic loadings. To date, the dependencies of Vs and G0 on saturation, especially in high suction range, are still not well understood because of the limited testing methodology and experimental evidence. In this study, the authors present a new laboratory instrumentation of measuring shear wave propagation in different types of unsaturated soils. Low relative humidity and water mist injection environment are used for measuring shear wave velocity under both drying and wetting conditions. Bender element technique was used to measure the shear wave responses. Step function was used as excitation, and determination of a first arrival time was identified and consistently used for all shear wave measurements. Shear wave evoluti...
43 citations
TL;DR: In this article, the normal force of magnetic microparticles subjected to magnetic fields was investigated using a rotational rheometer. And the authors found that the normal forces exhibited a high value plateau at low shear, followed by a decrease as the suspensions started to flow and a final low-value plateau at high shear.
Abstract: This work reports an experimental and theoretical study on the normal force developed by suspensions of magnetic microparticles subjected to magnetic fields. Experimental values of the normal force were obtained using a rotational rheometer, for a broad range of particle concentration in the suspensions. Applied magnetic fields up to 343 kA/m were generated in the plate-plate measuring geometry. It was found that the normal force exhibited a high-value plateau at low shear, followed by a decrease as the suspensions started to flow and a final low-value plateau at high shear. These three regions in the normal force vs shear rate curve were well correlated with the microscopic regimes in the suspensions: field-aligned structures filling the gap, inclined structures still filling the gap, and structures non-filling the gap. The theoretical model developed is based on the equilibrium between hydrodynamic and magnetostatic torques and forces in a field-induced aggregate of particles subjected to shear. The stress tensor was obtained and the normal force calculated as the integral of the stress over the total surface of the rotational plate. A good correspondence among the theoretical and experimental values was obtained.
43 citations
TL;DR: In this paper, the authors measured mean velocity, normal Reynolds stress and pressure drop measurements with 0.4 to 0.6% by weight aqueous solutions of Tylose, a methylhydroxil cellulose (molecular weight 6000) from Hoechst after a selection process from a set of low molecular weight fluids.
Abstract: Detailed mean velocity, normal Reynolds stress and pressure drop measurements were carried out with 0.4 to 0.6% by weight aqueous solutions of Tylose, a methylhydroxil cellulose (molecular weight 6000) from Hoechst after a selection process from a set of low molecular weight fluids. The viscosity measurements of the Tylose solutions showed shear-thinning behaviour, and the oscillatory and creep tests measured elastic components of the stress of the order of the minimal detectable values by the rheometer. These low molecular weight polymer solutions delayed transition from the laminar to the turbulent regime and showed drag reductions of half that reported to occur with other low elasticity shear-thinning high molecular aqueous polymer solutions. Near the wall the axial turbulent stress was higher than with water, whereas the two transverse components of turbulence were reduced. This near-wall behaviour is typical of drag reducing fluids based on high molecular weight polymers, but in the core of the pipe the three components of turbulence were higher than for the water flows, especially in the radial and tangential directions.
43 citations