Buoyancy-driven dispersion in a layered porous rock

AbstractWe investigate the longitudinal dispersion of a passive tracer by a gravity-driven flow in a porous medium consisting of a series of independent horizontal layers connected to a constant pressure source. We show that in a formation of given vertical extent, the total flux is only weakly dependent on the number of layers, and is very similar to that in a single layer of the same total depth. However, although the flow speed in each layer is approximately uniform, the speed gradually increases with layer depth. As a result, if a pulse of tracer is released in the flow it will migrate more rapidly through the lower layers, leading to longitudinal dispersion of the tracer. Eventually, the location of the tracer in the different layers may become separated in space so that a sufficiently distant observation well would detect a series of discrete pulses of tracer rather than the original coherent input, as would occur in a single permeable layer. For a constant pressure source, at long times, the standard deviation of the longitudinal distribution of tracer asymptotes to a fraction of order 0.1 of the position of the centre of mass, depending on the number of layers and the overpressure of the source.

Download Full-text

Scaling properties of gravity-driven sediments

Nonlinear Processes in Geophysics ◽

10.5194/npg-2-178-1995 ◽

1995 ◽

Vol 2 (3/4) ◽

pp. 178-185 ◽

Cited By ~ 15

Author(s):

D. H. Rothman ◽

J. P. Grotzinger

Keyword(s):

Critical Thickness ◽

Sedimentary Basin ◽

Scaling Law ◽

Scaling Exponent ◽

Power Law Distribution ◽

Scaling Properties ◽

Number Of Layers ◽

Gravity Driven ◽

Gravity Driven Flow ◽

Open Question

Abstract. Recent field observations of the statistical distribution of turbidite and debris flow deposits are discussed. In some cases one finds a good fit over 1.5-2 orders of magnitude to the scaling law N(h) α h-B, where N(h) is the number of layers thicker than h. Observations show that the scaling exponent B varies widely from deposit to deposit, ranging from about 1/2 to 2. Moreover, one case is characterized by a sharp crossover in which B increases by a factor of two as h increases past a critical thickness. We propose that the variations in B, either regional or within the same deposit, are indicative of the geometry of the sedimentary basin and the rheological properties of the original gravity-driven flow. The origin of the power-law distribution remains an open question.

Download Full-text

EFFECT OF FLOCCULATING AGENTS ON DRAG IN GRAVITY-DRIVEN FLOW SYSTEMS

International Journal of Fluid Mechanics Research ◽

10.1615/interjfluidmechres.2017015534 ◽

2017 ◽

Vol 44 (4) ◽

pp. 339-347

Author(s):

M. K. S. V. Raghav ◽

Ravi Teja ◽

Chirravuri Subbarao

Keyword(s):

Flow Systems ◽

Gravity Driven ◽

Gravity Driven Flow

Download Full-text

Drag reduction using mixed solutions of hydrotrope and surfactant in gravity driven flow systems

i-manager’s Journal on Future Engineering and Technology ◽

10.26634/jfet.8.3.2218 ◽

2013 ◽

Vol 8 (3) ◽

pp. 22-27

Author(s):

M. Venkata Ramana ◽

◽

Ch. V. Subbarao ◽

P. V. Gopal singh ◽

Krishna Prasad K.M.M ◽

...

Keyword(s):

Drag Reduction ◽

Mixed Solutions ◽

Flow Systems ◽

Gravity Driven ◽

Gravity Driven Flow

Download Full-text

Portable analyzer for continuous monitoring of sulfur dioxide in gas stream based on amperometric detection and stabilized gravity-driven flow

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2015.11.008 ◽

2016 ◽

Vol 225 ◽

pp. 24-33 ◽

Cited By ~ 5

Author(s):

Mohamed A.R.A. Alnaqbi ◽

Muna S. Bufaroosha ◽

Mohamed H. Al-Marzouqi ◽

Sayed A.M. Marzouk

Keyword(s):

Sulfur Dioxide ◽

Continuous Monitoring ◽

Amperometric Detection ◽

Gravity Driven ◽

Portable Analyzer ◽

Gravity Driven Flow

Download Full-text

Plasmon modes in N-layer silicene structures

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/ac3c66 ◽

2021 ◽

Author(s):

Men Nguyen Van

Keyword(s):

Electric Field ◽

Random Phase ◽

Single Layer ◽

Plasmon Mode ◽

Orbit Coupling ◽

Collective Excitations ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Number Of Layers ◽

Plasmon Modes

Abstract We investigate the plasmon properties in N-layer silicene systems consisting of N, up to 6, parallel single-layer silicene under the application of an out-of-plane electric field, taking into account the spin-orbit coupling within the random-phase approximation. Numerical calculations demonstrate that N undamped plasmon modes, including one in-phase optical and (N-1) out-of-phase acoustic modes, continue mainly outside the single-particle excitation area of the system. As the number of layers increases, the frequencies of plasmonic collective excitations increase and can become much larger than that in single layer silicene, more significant for high-frequency modes. The optical (acoustic) plasmon mode(s) noticeably (slightly) decreases with the increase in the bandgap and weakly depends on the number of layers. We observe that the phase transition of the system weakly affects the plasmon properties, and as the bandgap caused by the spin-orbit coupling equal that caused by the external electric field, the plasmonic collective excitations and their broadening function in multilayer silicene behave similarly to those in multilayer gapless graphene structures. Our investigations show that plasmon curves in the system move toward that in single layer silicene as the separation increases, and the impacts of this factor can be raised by a large number of layers in the system. Finally, we find that the imbalanced carrier density between silicene layers significantly decreases plasmon frequencies, depending on the number of layers.

Download Full-text

Stacked Microchannel Heat Sinks for Liquid Cooling of Microelectronic Components

10.1115/imece2000-1537 ◽

2000 ◽

Author(s):

X. Wei ◽

Y. Joshi

Keyword(s):

Flow Rate ◽

Heat Sink ◽

Water Flow Rate ◽

Heat Removal ◽

Single Layer ◽

Heat Sinks ◽

Computationally Efficient ◽

Liquid Cooling ◽

Number Of Layers ◽

Microelectronic Components

Abstract A novel heat sink based on a multi-layer stack of liquid cooled microchannels is investigated. For a given pumping power and heat removal capability for the heat sink, the flow rate across a stack of microchannels is lower compared to a single layer of microchannels. Numerical simulations using a computationally efficient multigrid method [1] were carried out to investigate the detailed conjugate transport within the heat sink. The effects of the microchannel aspect ratio and total number of layers on thermal performance were studied for water as coolant. A heat sink of base area 10 mm by 10 mm with a height in the range 1.8 to 4.5 mm (2–5 layers) was considered with water flow rate in the range 0.83×10−6 m3/s (50 ml/min) to 6.67×10−6 m3/s (400 ml/min). The results of the computational simulations were also compared with a simplified thermal resistance network analysis.

Download Full-text

An overview of deep learning techniques

at - Automatisierungstechnik ◽

10.1515/auto-2018-0076 ◽

2018 ◽

Vol 66 (9) ◽

pp. 690-703 ◽

Cited By ~ 1

Author(s):

Michael Vogt

Keyword(s):

Deep Learning ◽

Single Layer ◽

Visual Image ◽

Image Understanding ◽

Number Of Layers ◽

Box Models ◽

Learning Techniques ◽

Engineering Work ◽

Computational Resources ◽

Black Box Models

Abstract Deep learning is the paradigm that profoundly changed the artificial intelligence landscape within only a few years. Although accompanied by a variety of algorithmic achievements, this technology is disruptive mainly from the application perspective: It considerably pushes the border of tasks that can be automated, changes the way products are developed, and is available to virtually everyone. Subject of deep learning are artificial neural networks with a large number of layers. Compared to earlier approaches with ideally a single layer, this allows using massive computational resources to train black-box models directly on raw data with a minimum of engineering work. Most successful applications are found in visual image understanding, but also in audio and text modeling.

Download Full-text

Two-Dimensional Convection Induced by Gravity and Centrifugal Forces in a Rotating Porous Layer Far Away from the Axis of Rotation

International Journal of Rotating Machinery ◽

10.1155/s1023621x98000074 ◽

1998 ◽

Vol 4 (2) ◽

pp. 73-90 ◽

Cited By ~ 19

Author(s):

Peter Vadasz ◽

Saneshan Govender

Keyword(s):

Rayleigh Number ◽

Porous Layer ◽

Temperature Fields ◽

Wave Number ◽

Marginal Stability ◽

Two Dimensional ◽

Wide Range ◽

Gravity Driven ◽

Gravity Driven Flow ◽

The Stability

The stability and onset of two-dimensional convection in a rotating fluid saturated porous layer subject to gravity and centrifugal body forces is investigated analytically. The problem corresponding to a layer placed far away from the centre of rotation was identified as a distinct case and therefore justifying special attention. The stability of a basic gravity driven convection is analysed. The marginal stability criterion is established in terms of a critical centrifugal Rayleigh number and a critical wave number for different values of the gravity related Rayleigh number. For any given value of the gravity related Rayleigh number there is a transitional value of the wave number, beyond which the basic gravity driven flow is stable. The results provide the stability map for a wide range of values of the gravity related Rayleigh number, as well as the corresponding flow and temperature fields.

Download Full-text