A numerical model that couples water flow and sediment transport over a non-cohesive bed is developed to simulate the initiation and evolution of transportational cyclic steps. Transportational cyclic steps are periodic bedforms characterized by corresponding hydraulic jumps that form when a supercritical flow erodes and deposits bottom sediments on a steep bed. The flow transition at the hydra...

Supercritical fluid technology is a rapidly expanding analytical technique. Here we give a brief insight into the background of supercritical fluid technology and how supercritical fluid extraction and supercritical fluid chromatography work in analysis. The applications of these two techniques in forensic science are known to be important. The main area of forensic use of supercritical fluid t...

This article carried out the extraction of sesame oil by using three extraction techniques: supercritical fluid extraction (SFE), Soxhlet and sequential extraction. The SFE was performed using supercritical carbon dioxide (SC-CO2) as solvent and ethanol as cosolvent. Tests were performed at 20 MPa, 35°C and a flow rate of 2.5 g CO2/min with a total extraction time of 210 minutes. The Soxhlet ex...

Different empirical models were used to describe the supercritical CO2 extraction of soybean oil obtained at series of operational parameters namely pressure, temperature, solvent flow rate and characteristic particle size. Process yields obtained by supercritical CO2 were up to 19.33%. Several kinetic models: Brunner, Kandiah and Spiro, Tan and Liou, Martinez et al. and Esquivel et al. were us...

The steady/unsteady flow of the BGK No. 1 supercritical airfoil is investigated by the solution of the Reynolds-Averaged Navier-Stokes equations with a two-equation k-ω turbulence model. The dual-time stepping method is used to march in time. Two steady cases ( 71 . 0 = Ma , 396 . 1 = α and 71 . 0 = Ma , 0 . 9 = α ) and one unsteady case ( 71 . 0 = Ma , 97 . 6 = α ), both with a far-stream 6 10...

The steady two-dimensional laminar flow past a stationary cylinder is well known to lose stability to a periodic flow at a supercritical Hopf bifurcation point as the flow rate is increased. It is less well known that the critical flow rate at which the instability occurs can be increased by rotating the cylinder about is own axis, and that at a fixed flow rate the vortex street can be eliminat...

National Institute of Standards and Technology Boulder, CO 80303 Sample injection in supercritical fluid chromatography (SFC) is usually performed using a combination of apparatus from liquid chromatography and capillary gas chromatography. The device most often consists of an injection valve (of the type used in liquid chromatography) followed by a flow splitter controlled by a restrictor. It ...

Positively charged ions were produced in supercritical helium at temperatures from 6 to 10 K and up to 2 MPa using a corona discharge. Their mobility was measured via current-voltage curves, and the hydrodynamic radius was derived using Stokes law. An initial increase and subsequent decrease of hydrodynamic radius was observed and interpreted in terms of growth, compression and solidification o...

dissolution pressure and nozzle temperature effects on particle size and distribution were investigated for ress (rapid expansion of supercritical solution) process. supercritical co2 was used as solvent and ibuprofen was applied as the model component in all runs. the resulting ibuprofen nano-particles (about 50 nm in optimized runs) were analyzed by sem and laser diffraction particle size ana...