scholarly journals Integrable unsteady motion with an application to ocean eddies

1998 ◽  
Vol 5 (3) ◽  
pp. 145-151
Author(s):  
A. D. Kirwan, Jr. ◽  
B. L. Lipphardt, Jr.
Keyword(s):  
Potential Vorticity ◽  
Particle Motion ◽  
Gulf Stream ◽  
Incompressible Flows ◽  
Unsteady Motion ◽  
Ring System ◽  
Time Dependent ◽  
Two Dimensional ◽  
Ocean Eddies ◽  
Multilayered Systems

Abstract. Application of the Brown-Samelson theorem, which shows that particle motion is integrable in a class of vorticity-conserving, two-dimensional incompressible flows, is extended here to a class of explicit time dependent dynamically balanced flows in multilayered systems. Particle motion for nonsteady two-dimensional flows with discontinuities in the vorticity or potential vorticity fields (modon solutions) is shown to be integrable. An example of a two-layer modon solution constrained by observations of a Gulf Stream ring system is discussed.

Simulation of a 2D Channel Flow Around a Square Obstacle with Lattice-Boltzmann (BGK) Automata

1998 ◽  
Vol 09 (08) ◽  
pp. 1129-1141 ◽  
Author(s):  
J. Bernsdorf ◽  
Th. Zeiser ◽  
G. Brenner ◽  
F. Durst
Keyword(s):  
Flow Field ◽  
Lattice Boltzmann ◽  
Incompressible Flows ◽  
Focal Point ◽  
Reynolds Numbers ◽  
Time Dependent ◽  
Blockage Ratio ◽  
Two Dimensional ◽  
Viscous Incompressible Flows ◽  
Turbulent Flow Field

Results for time-dependent, viscous, incompressible flows were investigated using the lattice-Boltzmann (BGK) automata. The decay of a synthetic turbulent flow field and the time evolution of an initial vortex were simulated for validation purposes. The focal point was the investigation of the instationary flow around a square obstacle in a two-dimensional channel for a range of Reynolds numbers between 80 and 300 and a blockage ratio of 0.125. The Strouhal number was measured for this case and found to be in the range of data given in the literature.

scholarly journals Gradient evolution for potential vorticity flows

2001 ◽  
Vol 8 (4/5) ◽  
pp. 253-263 ◽  
Author(s):  
S. Balasuriya
Keyword(s):  
Evolution Equation ◽  
Rossby Wave ◽  
Potential Vorticity ◽  
Incompressible Flows ◽  
Eddy Diffusivity ◽  
Two Dimensional ◽  
Time Zero ◽  
Gradient Evolution ◽  
Pv Gradient

Abstract. Two-dimensional unsteady incompressible flows in which the potential vorticity (PV) plays a key role are examined in this study, through the development of the evolution equation for the PV gradient. For the case where the PV is conserved, precise statements concerning topology-conservation are presented. While establishing some intuitively well-known results (the numbers of eddies and saddles is conserved), other less obvious consequences (PV patches cannot be generated, some types of Lagrangian and Eulerian entities are equivalent) are obtained. This approach enables an improvement on an integrability result for PV conserving flows (if there were no PV patches at time zero, the flow would be integrable). The evolution of the PV gradient is also determined for the nonconservative case, and a plausible experiment for estimating eddy diffusivity is suggested. The theory is applied to an analytical diffusive Rossby wave example.

Particle motion in vorticity‐conserving, two‐dimensional incompressible flows

1994 ◽  
Vol 6 (9) ◽  
pp. 2875-2876 ◽  
Author(s):  
Michael G. Brown ◽  
Roger M. Samelson
Keyword(s):  
Particle Motion ◽  
Incompressible Flows ◽  
Two Dimensional

Ideally conducting magnetostatic equilibria and associated time dependent, resistive flows

1971 ◽  
Vol 6 (1) ◽  
pp. 125-136 ◽  
Author(s):  
John C. Stevenson
Keyword(s):  
Magnetic Field ◽  
Energy Equation ◽  
Incompressible Flows ◽  
Neutral Point ◽  
Time Dependent ◽  
Two Dimensional ◽  
Exact Time ◽  
Field Lines ◽  
Time Dependent Solution ◽  
The Magnetic Field

Several types of two-dimensional solutions for the equations of magnetohydrodynamics are described. For all these solutions the magnetic field contains at least one hyperbolic neutral point. Two new magnetostatic equilibria are introduced for the ideally conducting case. The magnetic field associated with one of these is used to construct an exact time-dependent solution of the MilD equations where the fluid is necessarily at rest. In the case where the field lines are hyperbolae, it is demonstrated that retention of the energy equation (ordinarily decoupled for incompressible flows) implies that the flow beginning at rest, remains at trest

scholarly journals Stability of Two-Dimensional Viscous Incompressible Flows under Three-Dimensional Perturbations and Inviscid Symmetry Breaking

2013 ◽  
Vol 45 (3) ◽  
pp. 1871-1885 ◽  
Author(s):  
C. Bardos ◽  
M. C. Lopes Filho ◽  
Dongjuan Niu ◽  
H. J. Nussenzveig Lopes ◽  
E. S. Titi
Keyword(s):  
Symmetry Breaking ◽  
Incompressible Flows ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Viscous Incompressible Flows

scholarly journals 6-Amino-3-methyl-4-(3,4,5-trimethoxyphenyl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile

2014 ◽  
Vol 70 (8) ◽  
pp. o875-o876 ◽  
Author(s):  
Naresh Sharma ◽  
Goutam Brahmachari ◽  
Bubun Banerjee ◽  
Rajni Kant ◽  
Vivek K. Gupta
Keyword(s):  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Ring System ◽  
Boat Conformation ◽  
Two Dimensional ◽  
Compound C ◽  
Dimensional Network ◽  
Centroid Distance

In the title compound, C17H18N4O4, the dihedral angle between the benzene ring and 2,4-dihydropyrano[2,3-c]pyrazole ring system is 89.41 (7)°. The pyran moiety adopts a strongly flattened boat conformation. In the crystal, molecules are linked by N—H...N, N—H...O, C—H...N and C—H...O hydrogen bonds into an infinite two-dimensional network parallel to (110). There are π–π interactions between the pyrazole rings in neighbouring layers [centroid–centroid distance = 3.621 (1) Å].

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