scholarly journals The ejection of large non-oscillating droplets from a hydrophobic wedge in microgravity

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Logan J. Torres ◽  
Mark M. Weislogel
Keyword(s):  
Initial Conditions ◽  
Minimum Energy ◽  
Surface Wetting ◽  
Drop Dynamics ◽  
Capillary Phenomena ◽  
Fluidic Devices ◽  
Fluid Properties ◽  
Water Drops ◽  
System Geometry ◽  
Passive Phase

AbstractWhen confined within containers or conduits, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, system geometry, and initial conditions. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration and ejection of large inertial-capillary drops confined between tilted planar hydrophobic substrates (a.k.a., wedges). In our experiments, the brief nearly weightless environment of a 2.1 s drop tower allows for the study of such capillary dominated behavior for up to 10 mL water drops with migration velocities up to 12 cm/s. We control ejection velocities as a function of drop volume, substrate tilt angle, initial confinement, and fluid properties. We then demonstrate how such geometries may be employed as passive no-moving-parts droplet generators for very large drop dynamics investigations. The method is ideal for hand-held non-oscillatory ‘droplet’ generation in low-gravity environments.

scholarly journals Thermofluid Modelling of Large-Scale Orchards for Optimal Design and Control of Active Frost Prevention Systems

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 378
Author(s):  
Ercan Atam ◽  
Se-Woon Hong ◽  
Alessia Arteconi
Keyword(s):  
Optimal Design ◽  
Control Systems ◽  
Large Scale ◽  
Initial Conditions ◽  
Minimum Energy ◽  
Prunus Armeniaca ◽  
Thermal Dynamics ◽  
Heating Systems ◽  
And Control

Accurate modelling and simulation of temperature dynamics in large-scale orchards is important in many aspects, including: (i) for the calculation of minimum energy required to be used in optimal design of active frost prevention energy systems (fully renewable or partially renewable) to prevent freezing of fruit flowers, buds, or leaves; (ii) for testing frost prevention control systems before real-implementation which regulate active heating systems inside orchards targeted to prevent frost. To that end, in this study, first, a novel and sophisticated parametric computational thermofluid dynamics (CTFD) model for orchard air thermal dynamics for different orchard parameters (such as fruit type, climate, number of trees, their sizes, and distance between them) and boundary/initial conditions was developed and validated with field data from the literature. Next, the use of the developed parametric CTFD model was demonstrated through a case study to calculate the minimal thermal energy required to prevent frost under different frost levels in a test Prunus armeniaca orchard located in Malatya, Turkey, which is the world capital for dry apricot production.

scholarly journals Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Lihua Zuo ◽  
Ruud Weijermars
Keyword(s):  
Porous Media ◽  
Fluid Transport ◽  
Initial Conditions ◽  
Time Of Flight ◽  
Flight Path ◽  
Flow In Porous Media ◽  
Transport Mechanisms ◽  
Local Porosity ◽  
Fluid Properties ◽  
Porosity And Permeability

Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule  1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule  2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

An Analysis of Increasing the Purity of Ethylene Production in the Ethylene Fractionation Column by the Genetic Algorithm

2019 ◽  
Vol 15 (3) ◽  
Author(s):  
Asadollah Karimi ◽  
Hadi Soltani ◽  
Aydin Hasanzadeh
Keyword(s):  
Energy Consumption ◽  
Ethylene Production ◽  
Distillation Column ◽  
Initial Conditions ◽  
Minimum Energy ◽  
Operating Conditions ◽  
Reflux Ratio ◽  
Simulation And Optimization ◽  
Minimum Energy Consumption ◽  
Fractionation Column

AbstractDistillation columns are among the most common fractionation systems with numerous applications in petrochemical units. Hence, the optimization of these columns is a large step in reducing energy consumption and increasing process productivity. This study was, therefore, carried out as a case study of the simulation and optimization of the parameters influencing the ethylene production of the ethylene distillation column in an olefin unit. The two defined objective functions in this research were maximum mass flow of ethylene in the upstream flow of the distillation column and the minimum energy consumption in the distillation column. The optimal operating conditions for the independent variables were estimated using the NSGAII algorithm. The sensitivity analysis of the results was, thereafter, carried out and the optimization results introduced tray no. 71 as the most suitable feed location. In addition, the optimal reflux ratio and the optimal feed flow temperature were 5.26 and −18.49 °C, respectively. In this condition, the upstream ethylene flow rate and energy consumption in the unit increased by approximately 0.74 % and 0.9 % as compared to the initial conditions, respectively.

Characterizing the Initial Spray From Fire Suppression Devices

2006 ◽  
Author(s):  
Ning Ren ◽  
Andrew Blum ◽  
Di Wu ◽  
Andre´ W. Marshall
Keyword(s):  
Fire Suppression ◽  
Model Development ◽  
Model Performance ◽  
Injection Pressure ◽  
Cfd Models ◽  
Fluid Properties ◽  
Water Drops ◽  
In Fire ◽  
Suppression Systems

The performance of water-based fire suppression systems is governed by the dispersion of the water drops in the spray. Characterization of the spray is essential for predicting and evaluating the performance of these suppression systems. The dispersion of the spray is typically modeled using particle tracking methods. The accuracy of the spray predictions using this approach is quite sensitive to the initial spray specification. A physics based atomization model is proposed for specification of the initial spray. Inputs to the atomization model include injector geometry, injection pressure, ambient environment, and suppressant fluid properties. This modeling approach can be integrated with drop dispersion models and CFD models to characterize spray dispersion in quiescent environments or evaluate suppression performance in fire environments. In the current study, this atomization model is compared with measurements from an 'ideal' sprinkler to evaluate model performance and to support model development.

Three-dimensional viscous wakes

1962 ◽  
Vol 14 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Martin H. Steiger ◽  
Martin H. Bloom
Keyword(s):  
Boundary Layer ◽  
Turbulent Flows ◽  
Axial Symmetry ◽  
Constant Velocity ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Axial Velocity Distribution ◽  
Fluid Properties ◽  
Laminar And Turbulent Flows

The velocity fields of three-dimensional viscous wakes are examined with the use of the boundary-layer approximations, Oseen's linearization of the convective terms, and the assumption of constant fluid properties. Transform methods yield solutions for general types of initial conditions. As an illustration, the axial velocity distribution of a wake whose initial isovels (lines of constant velocity) are of elliptic shape and their decay to axial symmetry are demonstrated. Both laminar and turbulent flows are considered.

scholarly journals The breakup of levitating water drops observed with a high speed camera

2011 ◽  
Vol 11 (4) ◽  
pp. 11739-11769 ◽  
Author(s):  
C. Emersic ◽  
P. J. Connolly
Keyword(s):  
High Speed ◽  
Initial Conditions ◽  
Liquid Water Content ◽  
High Speed Camera ◽  
Size Spectra ◽  
Initial Drop ◽  
Drop Number ◽  
Water Drops ◽  
Cloud Evolution ◽  
Stochastic Coalescence

Abstract. A wind tunnel was used to interact water drops and were recorded using a high speed camera. Three distinct collisional breakup types were observed and the drop size spectra from each were analysed for comparison with parameterisations constructed by Low and List (1982a). The spectra predicted by the parameterisations did not accurately correlate with the observed breakup distributions for each breakup type when applied to the relatively larger and similarly-sized drop-pairs of size 4–8 mm, comparable to those sometimes observed in nature. We discuss possible reasons for the discrepancies and suggest potential areas for future investigation. A computer programme was subsequently used to solve the stochastic coalescence and breakup equation using the Low and List breakup parameterisation, and the evolving drop spectra for a range of initial conditions were examined. Initial cloud liquid water content was found to be the most influential parameter, whereas initial drop number was found to have relatively little influence. This may have implications when considering the effect of aerosol on cloud evolution, raindrop formation and resulting drop spectra.

scholarly journals Knots in the Skyrme–Faddeev model

2007 ◽  
Vol 463 (2087) ◽  
pp. 3001-3020 ◽  
Author(s):  
Paul Sutcliffe
Keyword(s):  
Global Minimum ◽  
Initial Conditions ◽  
Dimensional Space ◽  
Minimum Energy ◽  
Three Dimensional ◽  
Soliton Solutions ◽  
Projective Line ◽  
Rational Maps ◽  
Torus Knots ◽  
Faddeev Model

The Skyrme–Faddeev model is a modified sigma model in three-dimensional space, which has string-like topological solitons classified by the integer-valued Hopf charge. Numerical simulations are performed to compute soliton solutions for Hopf charges up to 16, with initial conditions provided by families of rational maps from the three-sphere into the complex projective line. A large number of new solutions are presented, including a variety of torus knots for a range of Hopf charges. Often these knots are only local energy minima, with the global minimum being a linked solution, but for some values of the Hopf charge they are good candidates for the global minimum energy solution. The computed energies are in agreement with Ward's conjectured energy bound.

scholarly journals Rules for Flight Paths and Time of Flight for Flows in Porous Media with Heterogeneous Permeability and Porosity

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
Lihua Zuo ◽  
Ruud Weijermars
Keyword(s):  
Porous Media ◽  
Fluid Transport ◽  
Initial Conditions ◽  
Time Of Flight ◽  
Flight Path ◽  
Flow In Porous Media ◽  
Transport Mechanisms ◽  
Local Porosity ◽  
Fluid Properties ◽  
Porosity And Permeability

Porous media like hydrocarbon reservoirs may be composed of a wide variety of rocks with different porosity and permeability. Our study shows in algorithms and in synthetic numerical simulations that the flow pattern of any particular porous medium, assuming constant fluid properties and standardized boundary and initial conditions, is not affected by any spatial porosity changes but will vary only according to spatial permeability changes. In contrast, the time of flight along the streamline will be affected by both the permeability and porosity, albeit in opposite directions. A theoretical framework is presented with evidence from flow visualizations. A series of strategically chosen streamline simulations, including systematic spatial variations of porosity and permeability, visualizes the respective effects on the flight path and time of flight. Two practical rules are formulated. Rule  1 states that an increase in permeability decreases the time of flight, whereas an increase in porosity increases the time of flight. Rule  2 states that the permeability uniquely controls the flight path of fluid flow in porous media; local porosity variations do not affect the streamline path. The two rules are essential for understanding fluid transport mechanisms, and their rigorous validation therefore is merited.

Performance of Fluid Flow and Thermal Models for Subsea Satellite Wells

2001 ◽  
Author(s):  
Kazuioshi Minami ◽  
Alcino R. Almeida ◽  
Martha S. Santos ◽  
Alexandre P. Oliveira
Keyword(s):  
Reference Data ◽  
Temperature Profiles ◽  
Accurate Calculation ◽  
Wax Deposition ◽  
Flow Rates ◽  
State Data ◽  
Deep Waters ◽  
Campos Basin ◽  
Fluid Properties ◽  
System Geometry

Abstract Accurate calculation of pressure and temperature profiles is crucial for correctly predicting production rates and wax deposition and hydrate plugging tendencies of subsea wells and flowlines. In the present work, the commonly used empirical pressure drop correlations coupled with heat transfer models, both in the wellbore and the subsea flowlines, are evaluated against measured steady-state data from field operations. The reference data are from Campos Basin ultra-deep waters high flowrate subsea wells (from 1,000 to 1,850 m water depth, 3,280 to 6,070 ft), covering flow rates from 1,000 to 3,150 m3/d (6,280 to 20,000 bpd) through 4 1/2 to 5 1/2 in nominal diameter tubings and up to 11 km (6.8 mi) long, 6 in ID insulated flexible flowlines. Descriptions of the evaluated models, production system geometry, and fluid properties are included in the paper.

scholarly journals The motion of ellipsoidal particles in a viscous fluid

1923 ◽  
Vol 103 (720) ◽  
pp. 58-61 ◽  
Keyword(s):  
Viscous Fluid ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Minimum Energy ◽  
Steady Motion ◽  
Prolate Spheroid ◽  
Ellipsoidal Particles ◽  
Elliptic Cone ◽  
Axis Of Symmetry ◽  
Shearing Motion

In a recent paper* Dr. G. B. Jeffery has discussed the equations of motion of ellipsoidal particles immersed in a moving viscous fluid. He has solved the problem completely in The case of spheroidal particles immersed in a very viscous fluid which is moving parallel to a plane with a uniform shearing motion. his so1ution shows that the motion depends on the initial conditions of release of the Particle. The motion is periodic, and there appears to be no tendency for a particle to set itself so that its axis 1ies in any Particular direction. The Particle, in fact, takes up the rotation of the fluid, and its axis of symmetry describes a kind of elliptic cone round the direction of the vortex filaments, that is, round the direction which is perpendicular to the plane in which the motion of the fluid takes places. Though the ana1ysis, which neglects the inertia terms in the equations of motion, gives no indication of any tendency for the axis to set itself in any particular direction, Dr. Jeffery considers that ultimate1y the axis would probably adopt some special position, and he puts forward a " minimum energy ” hypothesis, which leads to the following definite, though unproved and unverified, results:— 1. A prolate spheroid, subject to the restriction imposed by this hypothesis, would set itself so that its long axis was Parallel to the vortex lines, and therefore perpendicular to the plane in which this undisturbed motion of the fluid takes places. It would then rotate with the fluid, which would move in steady motion relative to it.

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