scholarly journals Simulation of electrophoretic stretching of DNA in a microcontraction using an obstacle array for conformational preconditioning

2009 ◽  
Vol 3 (1) ◽  
pp. 012803 ◽  
Author(s):  
Daniel W. Trahan ◽  
Patrick S. Doyle
Keyword(s):  
Obstacle Array

Forecasting granular flow on steep terrains after interacting with an array of obstacles

2021 ◽  
Author(s):  
Su Yang ◽  
Xiaoliang Wang ◽  
Qingquan Liu
Keyword(s):  
Granular Material ◽  
Structural Design ◽  
Granular Flow ◽  
Hazard Mitigation ◽  
Protective Measure ◽  
Dynamical Process ◽  
Research Results ◽  
Mountainous Regions ◽  
Obstacle Array ◽  
Averaged Model

<p>Natural disasters such as landslides dominated by granular material may cause catastrophic consequences. Therefore, the protection of human-made facilities in mountainous areas is of great significance. An effective protective measure is to install an array of obstacles upstream of the structure that needs to be protected. We need to numerically simulate the interaction between granular flow and obstacle array, and forecast the flow path and stacking position of granular flow after interacting with an array of obstacles. The constitutive behavior and structure-interaction mode of granular material differs substantially from water flow-dominated hazards (e.g., floods). We have developed a depth-averaged model that can accurately simulate the interaction between granular flow and obstacles. Numerical simulations were performed for the case of granular flow facing a large number of different obstacles arrays to produce a dynamical process of granular flow and the depth changes of fixed detection points. We obtain different obstacles arrays by changing, including but not limited to, the type, geometric size of the obstacles, and row spacing of the arrays. We found that obstacles play roles of dissipation, deflection and hindrance, on the granular flow. For some types of obstacles, such as tetrahedron, the previous two mechanisms are dominant. Our research results show that the existence of obstacle arrays can indeed protect specific areas downstream. Furthermore, we can achieve better protection effects by changing the parameters of the array. These research results help us better forecast the result of the interaction between granular flow and an array of obstacles in space, and provide guidance for the structural design and assessment for hazard mitigation in mountainous regions. These findings advance the understanding of flow structures of fast granular flow facing obstacles, which provides guidance for structural design and assessment for hazard mitigation in mountainous.</p>

scholarly journals Directional clogging and phase separation for disk flow through periodic and diluted obstacle arrays

Soft Matter ◽  
2021 ◽  
Author(s):  
C. Reichhardt ◽  
C. J. O. Reichhardt
Keyword(s):  
Phase Separation ◽  
Obstacle Array ◽  
Flow Through

Disks flowing through a square obstacle array clog for incommensurate driving angles, forming either uniform or heterogeneous clogged states.

Comparisons of Transport and Dispersion Model Predictions of the Mock Urban Setting Test Field Experiment

2006 ◽  
Vol 45 (10) ◽  
pp. 1414-1428 ◽  
Author(s):  
Steve Warner ◽  
Nathan Platt ◽  
James F. Heagy ◽  
Jason E. Jordan ◽  
George Bieberbach
Keyword(s):  
Field Experiment ◽  
Dispersion Model ◽  
Terrorist Attack ◽  
Sonic Anemometer ◽  
The United States ◽  
Urban Setting ◽  
Urban Region ◽  
Test Field ◽  
Obstacle Array ◽  
Meteorological Observations

Abstract The potential effects of a terrorist attack involving the atmospheric release of chemical, biological, radiological, nuclear, or other hazardous materials continue to be of concern to the United States. The Defense Threat Reduction Agency has developed a Hazard Prediction Assessment Capability (HPAC) that includes initial features to address hazardous releases within an urban environment. Improved characterization and understanding of urban transport and dispersion are required to allow for more robust modeling. In 2001, a scaled urban setting was created in the desert of Utah using shipping containers, and tracer gases were released. This atmospheric tracer and meteorological study is known as the Mock Urban Setting Test (MUST). This paper describes the creation of sets of HPAC predictions and comparisons with the MUST field experiment. Strong consistency between the conclusions of this study and a previously reported HPAC evaluation that relied on urban tracer observations within the downtown area of Salt Lake City was found. For example, in both cases, improved predictions were associated with the inclusion of a simple empirically based urban dispersion model within HPAC, whereas improvements associated with the inclusion of a more computationally intensive wind field module were not found. The use of meteorological observations closest to the array and well above the obstacle array—the sonic anemometer measurements 16 m above ground level—resulted in predictions with the best fit to the observed tracer concentrations. The authors speculate that including meteorological observations or vertical wind profiles above or upwind of an urban region might be a sufficient input to create reasonable HPAC hazard-area predictions.

THE EFFECT OF AN ARRAY OF OBSTACLES ON HEAT CONDUCTION IN GASES

1963 ◽  
Vol 41 (11) ◽  
pp. 1883-1894
Author(s):  
C. F. Mate
Keyword(s):  
Heat Conduction ◽  
Pressure Range ◽  
Cell Model ◽  
Temperature Data ◽  
Obstacle Array ◽  
Helium Gas ◽  
Wide Pressure Range ◽  
A Cell ◽  
Low Pressures ◽  
Wide Pressure

The main features of heat conduction in an obstructed gas are described with the help of a cell model of the obstacle array. An expression is derived for calculation of the average conductivity of the obstructed gas over a wide pressure range extending to indefinitely low pressures. Conductivities calculated from this expression are compared with low-temperature data for helium gas in powdered alumina. The relevant transport properties of gases are summarized in an appendix.

scholarly journals Dispersion through an obstacle array: a wind tunnel investigation

2006 ◽  
Author(s):  
V. Garbero ◽  
P. Mejan ◽  
R. Perkins ◽  
P. Salizzoni ◽  
L. Soulhac
Keyword(s):  
Wind Tunnel ◽  
Obstacle Array

scholarly journals Commensurate states and pattern switching via liquid crystal skyrmions trapped in a square lattice

Soft Matter ◽  
2020 ◽  
Vol 16 (13) ◽  
pp. 3338-3343 ◽  
Author(s):  
A. Duzgun ◽  
C. Nisoli ◽  
C. J. O. Reichhardt ◽  
C. Reichhardt
Keyword(s):  
Liquid Crystal ◽  
Square Lattice ◽  
Rich Variety ◽  
Obstacle Array

Using continuum based simulations we show that a rich variety of skyrmion liquid crystal states can be realized in the presence of a periodic obstacle array.

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