scholarly journals New numerical scheme to compute three-dimensional configurations of quasiequilibrium compact stars in general relativity: Application to synchronously rotating binary star systems

1999 ◽  
Vol 61 (2) ◽  
Author(s):  
Fumihiko Usui ◽  
Kōji Uryū ◽  
Yoshiharu Eriguchi
Keyword(s):  
General Relativity ◽  
Numerical Scheme ◽  
Binary Star ◽  
Three Dimensional ◽  
Compact Stars

scholarly journals FAÇADE DESIGN EFFECT ON CROSS-VENTILATION IN TAIWANESE SCHOOL BUILDINGS

2013 ◽  
Vol 8 (2) ◽  
pp. 90-111 ◽  
Author(s):  
W.H. Chiang ◽  
H.H. Hsu ◽  
J.S. Huang
Keyword(s):  
Numerical Scheme ◽  
Wind Profile ◽  
Incident Angle ◽  
Three Dimensional ◽  
Windward Side ◽  
School Buildings ◽  
Breathing Zone ◽  
Air Exchange Rate ◽  
Computational Fluid Dynamics Cfd ◽  
Shading Devices

This study performed a three-dimensional numerical prediction for the induced airflow patterns and mean age of air (MAGE) around and inside a naturally ventilated school building, while accounting for the wind profile effect. Various fenestrations, hallways, and shading devices on the windward side of building were analyzed to determine how they affected wind velocity, the incident angle of airflow, and MAGE distribution inside classrooms. The numerical scheme is based on a commercial computational fluid dynamics (CFD) code, PHOENICS. The incline of incoming wind was observed on higher floors that decreased the air exchange rate in the simulated room. The inclined airflow could be effectively deflected downward through the breathing zone by hallways, 1.2-m shades as overhangs, and 0.6-m louvers. Based on this research, an appropriate combination of external attachments on the windward side of building façade can be utilized to enhance ventilation in school buildings. (See Appendix 1 for nomenclature.)

Embedded class solutions compatible for physical compact stars in general relativity

2018 ◽  
Vol 54 (5) ◽  
Author(s):  
Ksh. Newton Singh ◽  
Neeraj Pant ◽  
Neeraj Tewari ◽  
Anil K. Aria
Keyword(s):  
General Relativity ◽  
Compact Stars

scholarly journals Compact stars in the pseudo-complex general relativity

2018 ◽  
Vol 1143 ◽  
pp. 012002
Author(s):  
C. A. Zen Vasconcellos ◽  
J. E. S. Costa ◽  
D. Hadjimichef ◽  
M. V. T. Machado ◽  
F. Köpp ◽  
...  
Keyword(s):  
General Relativity ◽  
Compact Stars ◽  
Complex General Relativity

scholarly journals Study of charged compact stars with class 1 metric under general relativity

2019 ◽  
Vol 97 (12) ◽  
pp. 1323-1331 ◽  
Author(s):  
S.K. Maurya ◽  
S. Roy Chowdhury ◽  
Saibal Ray ◽  
B. Dayanandan
Keyword(s):  
General Relativity ◽  
Compact Star ◽  
Space Time ◽  
Electron Cloud ◽  
Compact Stars ◽  
Stellar Structure ◽  
Spherically Symmetric ◽  
Class 1 ◽  
Maxwell Space ◽  
Physical Tests

In the present paper we study compact stars under the background of Einstein–Maxwell space–time, where the 4-dimensional spherically symmetric space–time of class 1 along with the Karmarkar condition has been adopted. The investigations, via the set of exact solutions, show several important results, such as (i) the value of density on the surface is finite; (ii) due to the presence of the electric field, the outer surface or the crust region can be considered to be made of electron cloud; (iii) the charge increases rapidly after crossing a certain cutoff region (r/R ≈ 0.3); and (iv) the avalanche of charge has a possible interaction with the particles that are away from the center. As the stellar structure supports all the physical tests performed on it, therefore the overall observation is that the model provides a physically viable and stable compact star.

An Investigation Into Nonlinear Growth Rate of Two-Dimensional and Three-Dimensional Single-Mode Richtmyer–Meshkov Instability Using an Arbitrary-Lagrangian–Eulerian Algorithm

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Mike Probyn ◽  
Ben Thornber ◽  
Dimitris Drikakis ◽  
David Youngs ◽  
Robin Williams
Keyword(s):  
Growth Rate ◽  
Numerical Scheme ◽  
Initial Conditions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Single Mode ◽  
Computational Time ◽  
Initial Growth ◽  
Arbitrary Lagrangian Eulerian ◽  
Layer Width

This paper presents an investigation into the use of a moving mesh algorithm for solving unsteady turbulent mixing problems. The growth of a shock induced mixing zone following reshock, using an initial setup comparable to that of existing experimental work, is used to evaluate the behavior of the numerical scheme for single-mode Richtmyer–Meshkov instability (SM-RMI). Subsequently the code is used to evaluate the growth rate for a range of different initial conditions. The initial growth rate for three-dimensional (3D) SM Richtmyer–Meshkov is also presented for a number of different initial conditions. This numerical study details the development of the mixing layer width both prior to and after reshock. The numerical scheme used includes an arbitrary Lagrangian–Eulerian grid motion which is successfully used to reduce the mesh size and computational time while retaining the accuracy of the simulation results. Varying initial conditions shows that the growth rate after reshock is independent of the initial conditions for a SM provided that the initial growth remains in the linear regime.

INFLOW/OUTFLOW CONDITIONS FOR TIME-HARMONIC INTERNAL FLOWS

2002 ◽  
Vol 10 (02) ◽  
pp. 155-182 ◽  
Author(s):  
OLIVER V. ATASSI ◽  
AMR A. ALI
Keyword(s):  
Acoustic Waves ◽  
Numerical Scheme ◽  
Truncation Error ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Internal Flows ◽  
Vortex Sheets ◽  
Dimensional Interaction ◽  
Time Harmonic ◽  
Annular Cascade

Inflow/Outflow conditions are formulated for time-harmonic waves in a duct governed by the Euler equations. These conditions are used to compute the propagation of acoustic and vortical disturbances and the scattering of vortical waves into acoustic waves by an annular cascade. The outflow condition is expressed in terms of the pressure, thus avoiding the velocity discontinuity across any vortex sheets. The numerical solutions are compared with the analytical solutions for acoustic and vortical wave propagation with and without the presence of vortex sheets. Grid resolution studies are also carried out to discern the truncation error of the numerical scheme from the error associated with numerical reflections at the boundary. It is observed that even with the use of exponentially accurate boundary conditions, the dispersive characteristics of the numerical scheme may result in small reflections from the boundary that slow convergence. Finally, the three-dimensional interaction of a wake with a flat plate cascade is computed and the aerodynamic and aeroacoustic results are compared with those of lifting surface methods.

An Accurate and Efficient Euler Solver for Three-Dimensional Turbomachinery Flows

1986 ◽  
Author(s):  
C. F. Shieh ◽  
R. A. Delaney
Keyword(s):  
Numerical Solution ◽  
Euler Equations ◽  
Numerical Scheme ◽  
Three Dimensional ◽  
Curvilinear Coordinates ◽  
Analysis Method ◽  
Surfaces Of Revolution ◽  
Conservative Form ◽  
Turbine Cascades ◽  
Euler Solver

Accurate and efficient Euler equation numerical solution techniques are presented for analysis of three-dimensional turbomachinery flows. These techniques include an efficient explicit hopscotch numerical scheme for solution of the 3-D time-dependent Euler equations and an O-type body-conforming grid system. The hopscotch scheme is applied to the conservative form of the Euler equations written in general curvilinear coordinates. The grid is constructed by stacking from hub to shroud 2-D O-type grids on equally spaced surfaces of revolution. Numerical solution results for two turbine cascades are presented and compared with experimental data to demonstrate the accuracy of the analysis method.

Three Dimensional Fully Localized Waves on Ice-Covered Ocean

2013 ◽  
Author(s):  
Yong Liang ◽  
M.-Reza Alam
Keyword(s):  
Numerical Scheme ◽  
Perturbation Technique ◽  
Three Dimensional ◽  
Multiple Scale ◽  
Governing Equations ◽  
Weakly Nonlinear ◽  
Scale Perturbation ◽  
Speed Of Propagation ◽  
Localized Waves ◽  
Mean Current

We have recently shown [1] that fully-localized three-dimensional wave envelopes (so-called dromions) can exist and propagate on the surface of ice-covered waters. Here we show that the inertia of the ice can play an important role in the size, direction and speed of propagation of these structures. We use multiple-scale perturbation technique to derive governing equations for the weakly nonlinear envelope of monochromatic waves propagating over the ice-covered seas. We show that the governing equations simplify to a coupled set of one equation for the envelope amplitude and one equation for the underlying mean current. This set of nonlinear equations can be further simplified to fall in the category of Davey-Stewartson equations [2]. We then use a numerical scheme initialized with the analytical dromion solution of DSI (i.e. shallow-water and surface-tension dominated regimes of Davey-Stewartson equation) to look for dromion solution of our equations. Dromions can travel over long distances and can transport mass, momentum and energy from the ice-edge deep into the solid ice-cover that can result in the ice cracking/breaking and also in posing dangers to icebreaker ships.

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