scholarly journals Solute transport by suspended buoyant particles

2021 ◽  
Vol 249 ◽  
pp. 09002
Author(s):  
Iván Colecchio ◽  
Natalia Arze ◽  
Georgina Flores ◽  
Ana Quijandria ◽  
Alejandro Boschan
Keyword(s):  
Solute Transport ◽  
Solid Fraction ◽  
Light Transmission ◽  
Solute Concentration ◽  
Suspended Particles ◽  
Sharp Interface ◽  
Transmission Technique ◽  
Fingering Instability ◽  
Mass Discharge ◽  
Hele Shaw Cell

The transport of a colouring solute, driven by the buoyant displacement of microscopic suspended particles, and in the absence of net flow, is studied experimentally in a Hele Shaw cell. Initially, a sharp interface between a transparent fluid without particles and an underlying coloured suspension is obtained. From this situation, the suspended particles rise, carrying the solute in the form of a fingering instability across the interface, where a light transmission technique is used to measure the local solute concentration. This one attains an asymptotic value that increases with the solid fraction ϕ of suspended particles, and decreases with the distance to the interface. The solute mass discharge also increases with ϕ, always being relatively small (< 3%). The onset and development of the instability as the mechanism driving the transport of the solute is discussed.

Classification and quantification of downslope erosion from a geosynthetic clay liner (GCL) when covered only by a black geomembrane

2015 ◽  
Vol 52 (4) ◽  
pp. 395-412 ◽  
Author(s):  
R.W.I. Brachman ◽  
A. Rentz ◽  
R.K. Rowe ◽  
W.A. Take
Keyword(s):  
Classification System ◽  
Soil Cover ◽  
Light Transmission ◽  
Test Site ◽  
Field Observations ◽  
Composite Liner ◽  
Geosynthetic Clay Liner ◽  
Clay Liner ◽  
Transmission Technique ◽  
Field Investigations

Field observations of downslope bentonite erosion from a geosynthetic clay liner (GCL) covered by only a black geomembrane are reported for a composite liner left exposed without a protective soil cover for much longer than recommended by the GCL manufacturer. A new nondestructive, light-transmission technique developed to investigate bentonite erosion features in the field is presented. A classification system is developed to describe the type of erosion features observed. Results from five field investigations at the Queen’s University Environmental Liner Test Site (QUELTS II) are reported to quantify the onset, progression, and severity of downslope erosion for one particular geotextile-encased, needle-punched GCL for exposure periods of between 7 weeks and 1.3 years. The first significant erosion feature (type “E”with bentonite loss narrower than 2.5 cm) was observed after 6 months of exposure. Irrecoverable erosion features (type “EE” with bentonite loss wider than 2.5 cm) were observed after 12 months of exposure. These findings highlight the need to follow the manufacturer’s recommendations for timely covering of a composite liner with soil following liner installation.

scholarly journals Flattening of Diluted Species Profile via Passive Geometry in a Microfluidic Device

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 839
Author(s):  
Michael Miles ◽  
Biddut Bhattacharjee ◽  
Nakul Sridhar ◽  
Apresio Kefin Fajrial ◽  
Kerri Ball ◽  
...  
Keyword(s):  
Solute Transport ◽  
Concentration Profile ◽  
Microfluidic Channel ◽  
Region Of Interest ◽  
Solute Concentration ◽  
Cross Sectional ◽  
Driven Systems ◽  
Solute Profile ◽  
Dynamics Simulations ◽  
Pressure Driven

In recent years, microfluidic devices have become an important tool for use in lab-on-a-chip processes, including drug screening and delivery, bio-chemical reactions, sample preparation and analysis, chemotaxis, and separations. In many such processes, a flat cross-sectional concentration profile with uniform flow velocity across the channel is desired to achieve controlled and precise solute transport. This is often accommodated by the use of electroosmotic flow, however, it is not an ideal for many applications, particularly biomicrofluidics. Meanwhile, pressure-driven systems generally exhibit a parabolic cross-sectional concentration profile through a channel. We draw inspiration from finite element fluid dynamics simulations to design and fabricate a practical solution to achieving a flat solute concentration profile in a two-dimensional (2D) microfluidic channel. The channel possesses geometric features to passively flatten the solute profile before entering the defined region of interest in the microfluidic channel. An obviously flat solute profile across the channel is demonstrated in both simulation and experiment. This technology readily lends itself to many microfluidic applications which require controlled solute transport in pressure driven systems.

scholarly journals Direct characterization of solute transport in unsaturated porous media using fast X-ray synchrotron microtomography

2020 ◽  
Vol 117 (38) ◽  
pp. 23443-23449 ◽  
Author(s):  
Sharul Hasan ◽  
Vahid Niasar ◽  
Nikolaos K. Karadimitriou ◽  
Jose R. A. Godinho ◽  
Nghia T. Vo ◽  
...  
Keyword(s):  
Solute Transport ◽  
High Speed ◽  
Three Dimensional ◽  
Concentration Field ◽  
Solute Concentration ◽  
Breakthrough Curves ◽  
Pore Scale ◽  
X Ray ◽  
Long Tails ◽  
Computed Microtomography

Solute transport in unsaturated porous materials is a complex process, which exhibits some distinct features differentiating it from transport under saturated conditions. These features emerge mostly due to the different transport time scales at different regions of the flow network, which can be classified into flowing and stagnant regions, predominantly controlled by advection and diffusion, respectively. Under unsaturated conditions, the solute breakthrough curves show early arrivals and very long tails, and this type of transport is usually referred to as non-Fickian. This study directly characterizes transport through an unsaturated porous medium in three spatial dimensions at the resolution of 3.25 μm and the time resolution of 6 s. Using advanced high-speed, high-spatial resolution, synchrotron-based X-ray computed microtomography (sCT) we obtained detailed information on solute transport through a glass bead packing at different saturations. A large experimental dataset (>50 TB) was produced, while imaging the evolution of the solute concentration with time at any given point within the field of view. We show that the fluids’ topology has a critical signature on the non-Fickian transport, which yet needs to be included in the Darcy-scale solute transport models. The three-dimensional (3D) results show that the fully mixing assumption at the pore scale is not valid, and even after injection of several pore volumes the concentration field at the pore scale is not uniform. Additionally, results demonstrate that dispersivity is changing with saturation, being twofold larger at the saturation of 0.52 compared to that at the fully saturated domain.

Numerical simulations of a viscous-fingering instability in a fluid with a temperature-dependent viscosity

2006 ◽  
Vol 84 (4) ◽  
pp. 273-287 ◽  
Author(s):  
Kristi E Holloway ◽  
John R Bruyn
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Viscosity Ratio ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Cell Width ◽  
Inlet Velocity ◽  
Fingering Instability ◽  
Dependent Viscosity ◽  
Hele Shaw Cell

We have performed numerical simulations of the flow of hot glycerine as it displaces colder, more viscous glycerine in a radial Hele–Shaw cell. We find that fingering occurs for sufficiently high inlet velocities and viscosity ratios. The wavelength of the instability is independent of inlet velocity and viscosity ratio, but depends weakly on cell width. The growth rate of the fingers is found to increase with inlet velocity and decrease with the cell width. We compare our results with those from experiments.PACS No.: 47.54.–r

Effect of indomethacin on papillary solute concentration in the potassium-deficient rat

1986 ◽  
Vol 250 (1) ◽  
pp. F97-F102
Author(s):  
Y. Takamitsu ◽  
R. T. Kunau
Keyword(s):  
Solute Transport ◽  
Plasma Flow ◽  
Solute Concentration ◽  
Potassium Deficiency ◽  
Base Line ◽  
Experimental Setting ◽  
Solute Addition ◽  
Multiple Factors

Administration of indomethacin or meclofenamate to normal rats increases renal papillary solute concentration primarily by enhancing solute addition. A reduction in papillary solute concentration is characteristic of potassium deficiency. Of the multiple factors probably responsible for this reduction, several can be influenced by indomethacin or meclofenamate. The present study examined the effect of indomethacin on papillary solute concentration in the potassium-deficient rat. Indomethacin increased papillary solute concentration in normal but not potassium-deficient rats when studied in the conscious hydropenic state. Since indomethacin could increase papillary plasma flow in the potassium-deficient rat, potentially negating any enhancement of solute transport into the papilla, papillary plasma flow and papillary Cl concentration were determined in anesthetized surgically manipulated rats. Base-line papillary Cl concentrations were reduced in this setting. Indomethacin increased papillary plasma flow only in potassium-deficient rats but increased papillary Cl concentration equivalently in normal and potassium-deficient rats. The ability of indomethacin to increase papillary solute concentration in the potassium-deficient rat seemingly depends upon the experimental setting.

scholarly journals Viscous fingering in a radial elastic-walled Hele-Shaw cell

2018 ◽  
Vol 849 ◽  
pp. 163-191 ◽  
Author(s):  
Draga Pihler-Puzović ◽  
Gunnar G. Peng ◽  
John R. Lister ◽  
Matthias Heil ◽  
Anne Juel
Keyword(s):  
Stability Analysis ◽  
Flow Rate ◽  
Small Amplitude ◽  
Viscous Fingering ◽  
Flow Rates ◽  
Injection Flow ◽  
Fingering Instability ◽  
Air Liquid Interface ◽  
Hele Shaw Cell ◽  
Axisymmetric Perturbations

We study the viscous-fingering instability in a radial Hele-Shaw cell in which the top boundary has been replaced by a thin elastic sheet. The introduction of wall elasticity delays the onset of the fingering instability to much larger values of the injection flow rate. Furthermore, when the instability develops, the fingers that form on the expanding air–liquid interface are short and stubby, in contrast with the highly branched patterns observed in rigid-walled cells (Pihler-Puzović et al., Phys. Rev. Lett., vol. 108, 2012, 074502). We report the outcome of a comprehensive experimental study of this problem and compare the experimental observations to the predictions from a theoretical model that is based on the solution of the Reynolds lubrication equations, coupled to the Föppl–von-Kármán equations which describe the deformation of the elastic sheet. We perform a linear stability analysis to study the evolution of small-amplitude non-axisymmetric perturbations to the time-evolving base flow. We then derive a simplified model by exploiting the observations (i) that the non-axisymmetric perturbations to the sheet are very small and (ii) that perturbations to the flow occur predominantly in a small wedge-shaped region ahead of the air–liquid interface. This allows us to identify the various physical mechanisms by which viscous fingering is weakened (or even suppressed) by the presence of wall elasticity. We show that the theoretical predictions for the growth rate of small-amplitude perturbations are in good agreement with experimental observations for injection flow rates that are slightly larger than the critical flow rate required for the onset of the instability. We also characterize the large-amplitude fingering patterns that develop at larger injection flow rates. We show that the wavenumber of these patterns is still well predicted by the linear stability analysis, and that the length of the fingers is set by the local geometry of the compliant cell.

scholarly journals Solute Transport in the Element of Fractured Porous Medium with an Inhomogeneous Porous Block

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1028
Author(s):  
Bakhtiyor Khuzhayorov ◽  
Jabbor Mustofoqulov ◽  
Gafurjan Ibragimov ◽  
Fadzilah Md Ali ◽  
Bekzodjon Fayziev
Keyword(s):  
Porous Medium ◽  
Solute Transport ◽  
Solute Concentration ◽  
Graphical Form ◽  
Asymmetric Distribution ◽  
Nonlinear Kinetics ◽  
Kinetics Of Adsorption ◽  
Fractured Porous Medium ◽  
Slowing Down ◽  
Porous Block

In this paper, the problem of solute transport in a fractured-porous medium taking into account the non-equilibrium adsorption kinetic is studied. The solute transport in fractured-porous medium consisting of two fractures and a porous block between them located in a symmetric form is considered. The problem is then solved numerically by using the finite difference method. Based on the numerical results, the solute concentration and adsorption fields in the fractures and porous blocks are shown in graphical form. The effect of adsorption on the solute transport in a fractured-porous medium is then analyzed. In the case of different parameters in two zones, asymmetric distribution of the solute concentration and adsorption is obtained. The nonlinear kinetics of adsorption leads to an increase in the adsorption effects, conversely slowing down the rate of the distribution of concentration of the solute in the fluid.

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