119,340 research outputs found
Letter from J. M. Rushton to L. S. Joynes, 1864 October 13
No full textLetter from J. M. Rushton to L. S. Joynes expressing interest in attending lectures at the Medical College of Virginia.https://scholarscompass.vcu.edu/san/1099/thumbnail.jp
Flow generated by radial flow impellers: PIV measurements and CFD simulations
No full textParticle image velocimetry (PIV) and computational fluid dynamics (CFD) have been used to investigate the single phase and gas-liquid flow generated by a Scaba SRGT turbine. The key details of the trailing vortices, the turbulent flow around the impeller blades and the accumulation of gas have been studied by using PIV measurements and CFD simulations. Both the experimental and numerical results show that the flow and the trailing vortices are not altered significantly upon gassing. The simulated results are generally in good agreement with the experimental findings. The CFD simulations also show that only small low-pressure regions exist behind the blades of the Scaba turbine compared with the very large lowpressure zones formed by the Rushton turbine. These results enable better understanding of the improved performance of the Scaba turbine for gas-liquid dispersions compared with the Rushton turbine
Piv study of mixing characteristics in a stirred vessel with a non-Newtonian fluid
No full textPIV is used to analyze the flow induced by a Rushton turbine in a shear-thinning fluid, at constant input power, constant impeller velocity but different concentrations. The rheology of each shear-thinning fluid is first addressed. The mean velocity fields are compared. POD methodology is applied to estimate coherent structures and turbulence levels. Finally, the heterogeneity of shear rate is estimated and the spatial distribution of dissipation rate of total kinetic energy is addressed
Alien Registration- Rushton, Verne L. (Oakland, Kennebec County)
No full texthttps://digitalmaine.com/alien_docs/16551/thumbnail.jp
Naka-Rushton fit parameters.
No full text<p>Semi-Saturation contrast (SS%) and Contrast Gain parameters (CG) extracted from Naka-Rushton curve fits.</p
A hydrodynamic study of nickel suspension in stirred tanks
No full textMany studies on solid-liquid mixing have been dedicated to low density particles at low solids concentrations. In the present work, computational fluid dynamics (CFD) simulation and experimental methods were employed to study suspension of high density particles (nickel) at high solids concentration in water. The work first focused on establishing the velocity field in a liquid-only system and then progressed to a solid-liquid system. In the liquid-only system, the influence of tank geometry and simulation strategies, including turbulence models, on fluid flow pattern and mixing was investigated in a tank stirred by a Rushton turbine. The standard k-f. model gave better overall predictions of mean velocity fields than the k-ro and RNG k-f. models. The CFD simulation and experimental results obtained with the laser Doppler velocimetry (LDV) method showed that mixing time and homogenization energy decreased with a decrease in the impeller bottom clearance. It was further shown that there is a bottom clearance range in which a draft tube can aid mixing in a tank stirred by the Rushton turbine. In the solid-liquid system, a hydrofoil impeller was used to investigate the influence of simulation strategies, particle properties and hydrodynamic operating conditions on mixing features such as the off-bottom solids suspension, cloud height, solids concentration distribution and local particle size distribution. The simulation results were compared with experimental ones, in which the off-bottom solids suspension was determined visually and an optical attenuation technique was employed to determine the cloud height and solids concentration distribution. The local particle size distribution (PSD) in the tank was measured by a laser diffraction method. A better agreement between the simulation and experimental results was obtained with drag models that account for the solids loading or free stream turbulence than those that do not. It was shown that the Stokes law applies up to a diameter of 150 ~m for the nickel particles. A CFD simulation strategy for studying mixing of high density solids is proposed and it is shown that a CFD simulation method can be used to develop empirical models that predict mixing features. A CFD simulation approach that takes particle size into account gives predictions that are more representative of practical applications than the mono-size particle simulation approach. Reactor configurations and hydrodynamic parameters that improve mixing were identified. These can also aid optimal design of mixing systems
Gas-liquid mass transfer : influence of sparger location
No full textThe performance of three sparger diameters (DS = 0.6D, DS = D, DS = 1.6D) in combination with three positions (below, above or level with the impeller) for gas-liquid dispersion and mass transfer were evaluated in the case of the Rushton turbine and the A315 propeller in up- or down-pumping mode. The results show that the best results in terms of gas handling and mass transfer capacities are obtained for all impellers with the sparger placed below it and with a diameter at least equal to the impeller diameter. For the sparger position below the agitator, the kLa values of the Rushton turbine are greater than those of the A315 propeller, whatever the pumping mode. The A315 propeller in up-pumping mode is, however, more economically efficient in terms of mass transfer. In all cases, the up-pumping mode gives better results than the down-pumping one
Tobacco drought stress responses reveal new targets for Solanaceae crop improvement
No full textThis article proposes components of a core metabolic response to drought stress in plants and shows that some major responses to drought stress at the metabolome and transcriptome levels are family specific
England and Wales: stable fertility and pronounced social status differences.
No full textFor nearly three decades, the total fertility rate in England and Wales has remained high relative to other European countries, and stable at about 1.7 births per woman. In this chapter, we examine trends in both period and cohort fertility throughout the twentieth century, and demonstrate some important differences across demographic and social groups in the timing and quantum of fertility. Breaking with a market-oriented and laissez-faire approach to work and family issues, the last 10 years have seen the introduction of new social and economic policies aimed at providing greater support to families with children. However, the effect of the changes is likely to be limited to families on the lower end of the income scale. Rather than facilitating work and parenthood, some policies create incentives for a traditional gendered division of labour. Fertility appears to have remained stable despite, rather than because of, government actions.
England and Wales: Stable fertility and pronounced social status differences
No full textFor nearly three decades, the total fertility rate in England and Wales has remained high relative to other European countries, and stable at about 1.7 births per woman. In this chapter, we examine trends in both period and cohort fertility throughout the twentieth century, and demonstrate some important differences across demographic and social groups in the timing and quantum of fertility. Breaking with a market-oriented and laissez-faire approach to work and family issues, the last 10 years have seen the introduction of new social and economic policies aimed at providing greater support to families with children. However, the effect of the changes is likely to be limited to families on the lower end of the income scale. Rather than facilitating work and parenthood, some policies create incentives for a traditional gendered division of labour. Fertility appears to have remained stable despite, rather than because of, government actions.England, Europe, fertility, Wales
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