scholarly journals Can turbulent reconnection be fast in 2D?

2010 ◽  
Vol 6 (S271) ◽  
pp. 385-386
Author(s):  
K. Kulpa-Dybeł ◽  
G. Kowal ◽  
K. Otmianowska-Mazur ◽  
A. Lazarian ◽  
E. Vishniac
Keyword(s):  
Three Dimensional ◽  
Open Boundary ◽  
Initial Vector ◽  
Spectral Space ◽  
Two Dimensional ◽  
Open Boundary Conditions ◽  
Random Forcing ◽  
Potential Perturbation ◽  
Set Up ◽  
External Driving

AbstractTurbulent reconnection is studied by means of two-dimensional (2D) compressible magnetohydrodynamical numerical calculations. The process of homogeneous turbulence is set up by adding two-dimensional random forcing implemented in the spectral space at small wave numbers with no correlation between velocity and forcing. We apply the initial Harris current sheet configuration together with a density profile calculated from the numerical equilibrium of magnetic and gas pressures. We assume that there is no external driving of the reconnection. The reconnection develops as a result of the initial vector potential perturbation. We use open boundary conditions. Our main goal is to find the dependencies of reconnection rate on the uniform resistivity. We present that the reconnection speed depends on the Lindquist number in 2D in the case of low as well as high resolution. When we apply more powerful turbulence the reconnection is faster, however the speed of reconnection is smaller than in the case of our three-dimensional numerical simulations.

scholarly journals Effects of turbulence on magnetic reconnection: 3D numerical simulations

2008 ◽  
Vol 4 (S259) ◽  
pp. 671-674
Author(s):  
Katarzyna Otmianowska-Mazur ◽  
G. Kowal ◽  
A. Lazarian ◽  
E. Vishniac
Keyword(s):  
Current Sheet ◽  
Large Scale ◽  
Three Dimensional ◽  
Open Boundary ◽  
Initial Vector ◽  
Spectral Space ◽  
Diffusion Region ◽  
Open Boundary Conditions ◽  
Random Forcing ◽  
Set Up

AbstractTurbulent reconnection is studied by means of three dimensional (3D) compressible magnetohydrodynamical numerical calculations. The process of homogeneous turbulence is set up by adding three-dimensional solenoidal random forcing implemented in the spectral space at small wave numbers with no correlation between velocity and forcing. We apply the initial Harris current sheet configuration together with a density profile calculated from the numerical equilibrium of magnetic and gas pressures. We assume that there is no external driving of the reconnection. The reconnection develops as a result of the initial vector potential perturbation. We use open boundary conditions. Our main goal is to find the dependencies of reconnection rate on different properties of turbulence. The results of our simulations show that turbulence significantly affects the topology of magnetic field near the diffusion region. We present that the reconnection speed does not depend on the Reynolds numbers as well the magnetic diffusion. In addition, a fragmentation of current sheet decreases the disparity in inflow/outflow ratios. When we apply the large scale and more powerful turbulence the reconnection is faster.

scholarly journals Tidally induced lateral dispersion of the Storfjorden overflow plume

Ocean Science ◽  
2013 ◽  
Vol 9 (5) ◽  
pp. 885-899 ◽  
Author(s):  
F. Wobus ◽  
G. I. Shapiro ◽  
J. M. Huthnance ◽  
M. A. M. Maqueda ◽  
Y. Aksenov
Keyword(s):  
Ocean Circulation ◽  
Circulation Model ◽  
Bottom Layer ◽  
Horizontal Resolution ◽  
Open Boundary ◽  
Coastal Current ◽  
Fram Strait ◽  
Open Boundary Conditions ◽  
Shear Dispersion ◽  
Set Up

Abstract. We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard) into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

A two-dimensional diffusion model of the Venice lagoon and relative open boundary conditions

1987 ◽  
Vol 37 (1-2) ◽  
pp. 21-45 ◽  
Author(s):  
Camillo Dejak ◽  
Ileana Mazzei Lalatta ◽  
Ettore Messina ◽  
Giovanni Pecenik
Keyword(s):  
Boundary Conditions ◽  
Diffusion Model ◽  
Venice Lagoon ◽  
Open Boundary ◽  
Two Dimensional ◽  
Open Boundary Conditions ◽  
Dimensional Diffusion

On Three and Two-Dimensional Disturbances of Pipe Flow

1960 ◽  
Vol 27 (3) ◽  
pp. 381-389 ◽  
Author(s):  
Kurt Spielberg ◽  
Hans Timan
Keyword(s):  
Order Differential Equation ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Main Flow ◽  
Two Dimensional ◽  
Straight Pipe ◽  
Special Cases ◽  
Set Up ◽  
The Stability ◽  
The Given

A system of ordinary, coupled differential equations is set up for three-dimensional disturbances of Poiseuille flow in a straight pipe of circular cross section. The commonly treated equations are shown to be special cases arising from particular assumptions. It is shown that in the nonviscous, and therefore also in the general case, there exists, in contrast to the analogous problem in Cartesian co-ordinates, no transformation reducing the given problem to a two-dimensional one. A fourth-order differential equation is derived for disturbances independent of the direction of the main flow. The solutions, which are obtained, show that those two-dimensional disturbances, termed cross disturbances, decay with time and do therefore not disturb the stability of the main flow. Explicit expressions for the cross disturbances are obtained and a discussion of their nature is given.

Linear collapse of spatially linear, two-dimensional null points

2002 ◽  
Vol 68 (3) ◽  
pp. 221-235 ◽  
Author(s):  
C. MELLOR ◽  
V. S. TITOV ◽  
E. R. PRIEST
Keyword(s):  
Steady State ◽  
Boundary Conditions ◽  
Plasma Flow ◽  
Magnetic Force ◽  
Open Boundary ◽  
Two Dimensional ◽  
Open Boundary Conditions ◽  
Pressure Force ◽  
Large Current ◽  
Steady State Balance

A technique is developed for analysing the linear collapse properties of spatially linear two-dimensional null points with open boundary conditions. A treatment is given of the collapse of nulls which have current and flow so that they are initially in a steady-state balance between a magnetic force, a pressure force and a centrifugal force. This extends the previous results for initially current-free X-type nulls with no flow. It is found that all X-points, regardless of the current and flow tend to collapse. Also, O-points collapse in the absence of a plasma flow, but O-points with a large current and possessing a highly super-Alfvénic plasma flow can be stable against linear collapse.

scholarly journals Tidally-induced lateral dispersion of the Storfjorden overflow plume

2013 ◽  
Vol 10 (2) ◽  
pp. 691-726
Author(s):  
F. Wobus ◽  
G. I. Shapiro ◽  
J. M. Huthnance ◽  
M. A. M. Maqueda ◽  
Y. Aksenov
Keyword(s):  
Ocean Circulation ◽  
Circulation Model ◽  
Bottom Layer ◽  
Horizontal Resolution ◽  
Open Boundary ◽  
Coastal Current ◽  
Fram Strait ◽  
Open Boundary Conditions ◽  
Shear Dispersion ◽  
Set Up

Abstract. We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard) into Fram Strait and onto the Western Svalbard Shelf using a regional setup of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally-induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the Western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally-induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

scholarly journals Hydrodynamic and Hydrographic Modeling of Istanbul Strait

2019 ◽  
Author(s):  
Mehmet Melih Koşucu ◽  
Mehmet Cüneyd Demirel ◽  
V.S. Ozgur Kirca ◽  
Mehmet Özger
Keyword(s):  
Mixing Layer ◽  
Open Boundary ◽  
Roughness Coefficient ◽  
Model Parameters ◽  
Temperature Profiles ◽  
Open Boundary Conditions ◽  
Pass Filter ◽  
Low Pass Filter ◽  
The North ◽  
Set Up

The aim of this study is to model hydrodynamic processes of the Istanbul Strait with its stratified flow characteristic and calibrate the most important parameters using local and global search algorithms. For that two open boundary conditions are defined, which are in the North and South part of the Strait. Observed bathymetric, hydrographic, meteorological and water level data are used to set up the Delft3D-FLOW model. First, the sensitivities of model parameters on the numerical model outputs are assessed using PEST toolbox. Then, the model is calibrated based on the objective functions focusing on the flowrates of upper and lower layers. The salinity and temperature profiles of the Strait are only used for model validation. The results show that the calibrated model outputs of Istanbul Strait are reliable and consistent with the in-situ measurements. The sensitivity analysis reveals that the Spatial Low-Pass Filter Coefficient, Horizontal Eddy Viscosity, Prandtl-Schmidt Number, Slope in log-log Spectrum and Manning Roughness Coefficient are most sensitive parameters affecting flowrate performance of the model. The agreement between observed salinity profiles and simulated model outputs is promising whereas the match between observed and simulated temperature profiles is weak showing that the model can be improved particularly for simulating the mixing layer.

Essentials and Applications of 3D Printers used in Mathematical Technique

2021 ◽  
Vol 8 (1) ◽  
Keyword(s):  
3D Printing ◽  
Three Dimensional ◽  
Sixth Grade ◽  
Two Dimensional ◽  
Mathematical Technique ◽  
Creative Mind ◽  
3D Printers ◽  
Game Plan ◽  
Set Up ◽  
Experimental Group

In this paper we talk about the part of schools and their duty to go about as fast as could be expected to plan a game plan that will set up the future residents to manage this new reality. This study requires arranging of activity in various ways and on various planes, like labs, instructors, also, educational plans. 3D printing requires more significant levels of reasoning, advancement and imagination. It has the capacity to foster human creative mind and offer understudies the chance to imagine numbers, two dimensional shapes, and three-dimensional articles. The blend of reasoning, plan, and creation has massive ability to expand inspiration and fulfillment, with an exceptionally plausible expansion in an understudy's math and calculation accomplishments. The CAD framework incorporates an action instrument which empowers and elective route for figuring properties of the articles under thought and permits advancement of reflection and basic reasoning. The exploration strategy depended on correlation between a reference bunch and an experimental group; it was discovered that intercession altogether improved the reflection capacities of sixth grade understudies 3D printing innovation is a quick arising innovation. These days, 3D Printing is generally utilized on the planet. This paper presents the review of the sorts of 3D printing innovations, the use of 3D printing innovation and ultimately, the materials utilized for 3D printing innovation in assembling industry.

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