Experimental Investigation of Sand Jets Passing Through Immiscible Fluids

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Niyousha Mohammadidinani ◽  
Amir H. Azimi ◽  
Siamak Elyasi
Keyword(s):  
Reynolds Number ◽  
Laboratory Experiments ◽  
Spreading Rate ◽  
Immiscible Fluids ◽  
Cloud Formation ◽  
Time Data ◽  
Densimetric Froude Number ◽  
Different Shapes ◽  
Visualization Techniques ◽  
Excess Shear Stress

Laboratory experiments were conducted to study the dynamics of sand jets passing through two immiscible fluids. Different oil layer thicknesses, nozzle diameters, and sand masses were employed. Evolution of oily sand jets with time was investigated using image processing and boundary visualization techniques. Different shapes of the frontal head and trailing wave section were observed and cloud formation was classified into different categories based on Reynolds number, normalized oil layer thickness, and evolution time. It was found that the effect of Reynolds number on evolution of oily sand jets was more significant than the other parameters. Width and frontal velocity of oily sand jets were measured at different times. It was observed that oily sand jets became unstable after a distance of ten times larger than the nozzle diameter. Instability of oily sand jets caused intense spreading with a spreading rate of 0.4. The thin layer of oil encapsulated sand cluster was ruptured due to excess shear stress and caused bursting of the frontal head into a cloud of sand particles. Three different bursting mechanisms were observed and a correlation was found between the densimetric Froude number and the normalized bursting time. Data mining and boundary visualization techniques were used to model oily sand jets. Model trees were developed to classify and predict the growth of oily sand jets at different conditions. Modeling results indicated that the Model tree can predict the growth of sand jets with an uncertainty of ±8.2%, ±6.8%, and ±8.7% for width, velocity, and distance, respectively.

Asteroid collisions as origin of debris disks: Asteroid shape reconstruction from BNAO Rozhen photometry

2019 ◽  
Vol 15 (S350) ◽  
pp. 451-453
Author(s):  
G. Apostolovska ◽  
E. Vchkova Bebekovska ◽  
A. Kostov ◽  
Z. Donchev
Keyword(s):  
Laboratory Experiments ◽  
Extrasolar Planets ◽  
Shape Reconstruction ◽  
Inversion Method ◽  
Debris Disks ◽  
Shape Parameters ◽  
Zodiacal Cloud ◽  
Photometric Observations ◽  
Different Shapes ◽  
Asteroid Surface

AbstractAs a result of collisions during their lifetimes, asteroids have a large variety of different shapes. It is believed that high velocity collisions or rotational spin-up of asteroids continuously replenish the Sun’s zodiacal cloud and debris disks around extrasolar planets (Jewitt (2010)). Knowledge of the spin and shape parameters of the asteroids is very important for understanding collision asteroid processes. Lately photometric observations of asteroids showed that variations in brightness are not accompanied by variations in colour index which indicate that the shape of the lightcurve is caused by varying illuminations of the asteroid surface rather than albedo variations over the surface. This conclusion became possible when photometric investigations were combined with laboratory experiments (Dunlap (1971)). In this article using the convex lightcurve inversion method we obtained the sense of rotation, pole solutions and preliminary shape of 901 Brunsia.

scholarly journals A biogenic secondary organic aerosol source of cirrus ice nucleating particles

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Martin J. Wolf ◽  
Yue Zhang ◽  
Maria A. Zawadowicz ◽  
Megan Goodell ◽  
Karl Froyd ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Secondary Organic Aerosol ◽  
Global Climate ◽  
Compositional Analysis ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Cloud Formation ◽  
Ambient Atmosphere ◽  
Atmospheric Conditions ◽  
Mass Fractions

Abstract Atmospheric ice nucleating particles (INPs) influence global climate by altering cloud formation, lifetime, and precipitation efficiency. The role of secondary organic aerosol (SOA) material as a source of INPs in the ambient atmosphere has not been well defined. Here, we demonstrate the potential for biogenic SOA to activate as depositional INPs in the upper troposphere by combining field measurements with laboratory experiments. Ambient INPs were measured in a remote mountaintop location at –46 °C and an ice supersaturation of 30% with concentrations ranging from 0.1 to 70 L–1. Concentrations of depositional INPs were positively correlated with the mass fractions and loadings of isoprene-derived secondary organic aerosols. Compositional analysis of ice residuals showed that ambient particles with isoprene-derived SOA material can act as depositional ice nuclei. Laboratory experiments further demonstrated the ability of isoprene-derived SOA to nucleate ice under a range of atmospheric conditions. We further show that ambient concentrations of isoprene-derived SOA can be competitive with other INP sources. This demonstrates that isoprene and potentially other biogenically-derived SOA materials could influence cirrus formation and properties.

scholarly journals Determination of the uncertainty of mass flow measurement using the orifice for different values of the Reynolds number

2019 ◽  
Vol 213 ◽  
pp. 02022 ◽  
Author(s):  
Anna Golijanek-Jędrzejczyk ◽  
Andrzej Mrowiec ◽  
Robert Hanus ◽  
Marcin Zych ◽  
Dariusz Świsulski
Keyword(s):  
Reynolds Number ◽  
Mass Flow ◽  
Flow Measurement ◽  
Laboratory Experiments ◽  
Energy Industry ◽  
Maximum Difference ◽  
Know How ◽  
Simulation And Experiment ◽  
Extended Uncertainty

Standard orifice flowmeters are widely used in the chemical and energy industry. Therefore, it is essential to know how accurate the measurements made with these instruments are. The paper presents an estimation of measurement uncertainty of a liquid mass flow using the orifice plate. The authors will present the influence of ranges of the Reynolds number on the estimated uncertainty, obtained on the basis of simulation and laboratory experiments. The research was conducted for the central orifice in the Reynolds number 8,000 < Re < 21,000. The results of estimating the extended uncertainty of the measurement of water flow using simulation and experimental method, are convergent. The maximum difference in the extended uncertainty values of flow measurement for the simulation and experiment was 0.04.10-3 kg/s.

Numerical Prediction of Turbulent Flow in Rotating Cavities

1988 ◽  
Vol 110 (2) ◽  
pp. 202-211 ◽  
Author(s):  
A. P. Morse
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Predictive Accuracy ◽  
Turbulent Transport ◽  
Reynolds Numbers ◽  
Spreading Rate ◽  
Flow Conditions ◽  
Wide Range ◽  
Ekman Layers ◽  
Radial Outflow

Predictions of the isothermal, incompressible flow in the cavity formed between two corotating plane disks and a peripheral shroud have been obtained using an elliptic calculation procedure and a low turbulence Reynolds number k–ε model for the estimation of turbulent transport. Both radial inflow and outflow are investigated for a wide range of flow conditions involving rotational Reynolds numbers up to ∼106. Although predictive accuracy is generally good, the computed flow in the Ekman layers for radial outflow often displays a retarded spreading rate and a tendency to laminarize under conditions that are known from experiment to produce turbulent flow.

Flow Around Three Side-by-Side Square Cylinders and the Effect of the Cylinder Oscillation

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Bhupendra Singh More ◽  
Sushanta Dutta ◽  
Bhupendra Kumar Gandhi
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Drag Coefficient ◽  
Flow Structure ◽  
Power Spectra ◽  
Square Cylinders ◽  
Spacing Ratio ◽  
Hotwire Anemometry ◽  
Visualization Techniques ◽  
Flow Interference

Abstract In this study, the flow field over three square cylinders (SCs) arranged side by side is investigated in a low-speed wind tunnel. The experiments are performed with three similar SCs for Reynolds number (Re) 295. The influences of spacing ratio on the wake size, drag coefficient, and flow interference of the cylinders are reported with the hotwire anemometry, particle image velocimetry (PIV), and the flow visualization techniques. Special attention is paid to the oscillation given to the middle cylinder and its effect on flow structure and related forces. The spacing ratio (s/D) ranges from 1.5 to 3, whereas the forcing frequency ratio ranges from 0.5 to 2 with amplitude of 10% of the cylinder width. It is observed that the spacing influences the flow structure, and the vortex shedding mechanism strongly. A secondary frequency appears in the flow field for spacing ratio s/D = 2 and 3. Depending upon the spacing ratios, the flow pattern is seen to be asymmetric biased, symmetric biased, and weakly interactive. The wake interaction decreases with increase in spacing ratios. With the oscillations, the wake becomes more unstable and complex. Additional wake oscillation frequency appears in the power spectra. With an increase in spacing ratios, the drag coefficient decreases, whereas with oscillations, higher drag force is observed compared to a stationary cylinder. A correlation is developed between the time-averaged drag coefficient with cylinder spacing and Reynolds number.

scholarly journals When is high Reynolds number shear flow not turbulent?

2017 ◽  
Vol 824 ◽  
pp. 1-4 ◽  
Author(s):  
Steven A. Balbus
Keyword(s):  
Reynolds Number ◽  
Shear Flow ◽  
High Reynolds Number ◽  
Laboratory Experiments ◽  
Numerical Study ◽  
Accretion Discs ◽  
Large Reynolds Number ◽  
Rotating Flow ◽  
General Tendency ◽  
High Reynolds

Rotating flow in which the angular velocity decreases outward while the angular momentum increases is known as ‘quasi-Keplerian’. Despite the general tendency of shear flow to break down into turbulence, this type of flow seems to maintain stability at very large Reynolds number, even when nonlinearly perturbed, a behaviour that strongly influences our understanding of astrophysical accretion discs. Investigating these flows in the laboratory is difficult because secondary Ekman flows, caused by the retaining Couette cylinders, can become turbulent on their own. A recent high Reynolds number numerical study by Lopez & Avila (J. Fluid Mech., vol. 817, 2017, pp. 21–34) reconciles apparently discrepant laboratory experiments by confirming that this secondary flow recedes toward the axial boundaries of the container as the Reynolds number is increased, a result that enhances our understanding of nonlinear quasi-Keplerian flow stability.

scholarly journals Self-similarity of time-evolving plane wakes

1998 ◽  
Vol 367 ◽  
pp. 255-289 ◽  
Author(s):  
ROBERT D. MOSER ◽  
MICHAEL M. ROGERS ◽  
DANIEL W. EWING
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Initial Conditions ◽  
Spreading Rate ◽  
Momentum Thickness ◽  
Two Dimensional ◽  
Self Similarity ◽  
Order Of Magnitude ◽  
The Difference ◽  
Velocity Spectra

Direct numerical simulations of three time-developing turbulent plane wakes have been performed. Initial conditions for the simulations were obtained using two realizations of a direct simulation from a turbulent boundary layer at momentum-thickness Reynolds number 670. In addition, extra two-dimensional disturbances were added in two of the cases to mimic two-dimensional forcing. The wakes are allowed to evolve long enough to attain approximate self-similarity, although in the strongly forced case this self-similarity is of short duration. For all three flows, the mass-flux Reynolds number (equivalent to the momentum-thickness Reynolds number in spatially developing wakes) is 2000, which is high enough for a short k−5/3 range to be evident in the streamwise one-dimensional velocity spectra.The spreading rate, turbulence Reynolds number, and turbulence intensities all increase with forcing (by nearly an order of magnitude for the strongly forced case), with experimental data falling between the unforced and weakly forced cases. The simulation results are used in conjunction with a self-similar analysis of the Reynolds stress equations to develop scalings that approximately collapse the profiles from different wakes. Factors containing the wake spreading rate are required to bring profiles from different wakes into agreement. Part of the difference between the various cases is due to the increased level of spanwise-coherent (roughly two-dimensional) energy in the forced cases. Forcing also has a significant impact on flow structure, with the forced flows exhibiting more organized large-scale structures similar to those observed in transitional wakes.

LATTICE BOLTZMANN SIMULATIONS OF DROP DEFORMATION AND BREAKUP IN SHEAR FLOWS

2003 ◽  
Vol 17 (01n02) ◽  
pp. 21-26 ◽  
Author(s):  
T. INAMURO ◽  
R. TOMITA ◽  
F. OGINO
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Shear Flows ◽  
Immiscible Fluids ◽  
Drop Deformation ◽  
Lattice Boltzmann Simulations ◽  
Boltzmann Method

A lattice Boltzmann method for multicomponent immiscible fluids is applied to simulations of drop deformation and breakup in shear flows for various capillary numbers and viscosity ratios at three different Revnolds numbers, Re = 0.2, 1, 10. The effect of the Reynolds number on drop deformation and breakup in shear flows is investigated. It is found that the drop is easier to deform and to be ruptured as the Reynolds number increases.

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