Turbulent mixing at a shear-free density interface

The interaction of a sharp density interface with oscillating-grid-induced shear-free turbulence was experimentally investigated. A linear photodiode array was used in conjunction with laser-induced fluorescence to measure the concentration of dye that was initially only in the less dense layer. A laser-Doppler velocimeter was used to measure the vertical velocity in and above the density interface at a point where the dye concentration was also measured. Potential refractive-index-fluctuation problems were avoided using solutes that provided a homogeneous optical environment across the density interface. Internal wave spectra, amplitudes and velocities, as well as the vertical mass flux were measured. The results indicate that mixing occurs in intermittent bursts and that the gradient (local) Richardson number remains constant for a certain range of the overall Richardson number R_j, defined in terms of an integral lengthscale, buoyancy jump and turbulence intensity. The spectra of the internal waves decay as f^(−3) at frequencies below the maximum Brunt-Väisälä frequency. These findings give support to a model for oceanic mixing proposed by Phillips (1977) in which the internal waves are limited in their spectral density by sporadic local instabilities and breakdown to turbulence. The results also indicate that, for a certain R_j range, the thickness of the interfacial layer (normalized by the integral lengthscale of the turbulence) is a decreasing function of R_j. At sufficiently high R_j the interfacial thickness becomes limited by diffusive effects. Finally, we discuss a simple model for entrainment at a density interface in the presence of shear-free turbulence

Turbulence structure near a sharp density interface

The effects of a sharp density interface and a rigid flat plate on oscillating-grid induced shear-free turbulence were investigated experimentally. A two-component laser-Doppler velocimeter was used to measure turbulence intensities in and above the density interface (with matched refractive indices) and near the rigid flat plate. Energy spectra, velocity correlations, and kinetic energy fluxes were also measured. Amplification of the horizontal turbulent velocity, coupled with a sharp reduction in the vertical turbulent velocity, was observed near both the density interface and the flat plate. These findings are in agreement with some previous results pertaining to shear-free turbulence near rigid walls (Hunt & Graham 1978) and near density interfaces (Long 1978). The results imply that, near the density interface, the turbulent kinetic energy in the vertical velocity component is only a small fraction of the total turbulent kinetic energy and indicate that the effects of the anisotropy created by the density interface or the flat plate are confined to the large turbulence scales

Mathematical Model for the Equilibrium Flash Vaporization of the Nile Blend Crude Oil

Equilibrium Flash Vaporization (EFV) for the crude oil distillation is considered to be one of the crucial basis to simulate the true distillation operation in the distillation column. Classical procedures have been used to determine EFV of the crude oil, such as Maxwell and Edmister methods. Such methods are multi-graphical methods which are tedious and time consuming. Based on Maxwell graphical procedure, this paper is attempting to develop a new EFV mathematical model using experimental data from the Nile Blend crude oil. The developed model allows the process engineer to swiftly obtain the flash zone temperature of the Crude Distillation Unit (CDU) avoiding the tedious process of the graphical methods. Although the experimental data were taken from the Nile Blend oil, the same procedure could be followed to develop an EFV mathematical model for any other crude oi

Experimental sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2013

Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet cultivars with resistance to BNYVV and evaluate storability, 24 experimental cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2013 growing season in a randomized complete block design with 4 replications. At harvest on 11 October 2013, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 123 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 7 to 76%, weight loss ranged from 6.6 to 11.6%, sucrose losses ranged from 32 to 66%, and estimated recoverable sucrose ranged from 1,643 to 8,308 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining this resistance with storability will lead to considerable economic benefit for the sugar beet industry

Commercial sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2013

Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet cultivars with resistance to BNYVV and evaluate storability, 28 commercial cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2013 growing season in a randomized complete block design with 4 replications. At harvest on 11 October 2013, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 123 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 6 to 86%, weight loss ranged from 4.5 to 14.8%, sucrose losses ranged from 30 to 75%, and estimated recoverable sucrose ranged from 917 to 8,686 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining this resistance with storability will lead to considerable economic benefit for the sugar beet industry

Experimental sugar beet cultivars evaluated for rhizomania resistance and storability in Idaho, 2012

Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet cultivars with resistance to BNYVV and evaluate storability, 26 experimental cultivars were screened by growing them in a sugar beet field infested with BNYVV in Kimberly, ID during the 2012 growing season in a randomized complete block design with 4 replications. At harvest on 3 October 2012, roots were dug and evaluated for symptoms of rhizomania and also placed in an indoor commercial sugar beet storage building. After 134 days in storage, samples were evaluated for surface rot, weight loss, and sucrose loss. Surface root rot ranged from 34 to 90%, weight loss ranged from 8.4 to 15.4%, sucrose losses ranged from 33 to 72%, and estimated recoverable sucrose ranged from 1,997 to 7,601 lb/A. Given these response ranges, selecting cultivars for rhizomania resistance and combining it with storability will lead to considerable economic benefit for the sugar beet industry