Two finite-difference methods for, geophysical .fluid problems are described, and stability conditions of these schemes arc discussed. These two schemes are formulated based upon a similar procedure given by Lax and Wendroff in order to obtain a second-order accuracy in finite-difference equations. However, the two schemes show remarkable differcnces.io their computational stability. One scheme...

In this paper, an unified high-order algorithm for all speeds is developed. The preconditioning matrix of Weiss and Smith combined with a 5th-order WENO scheme for inviscid flux and a fully conservative 4th order central differencing for viscous terms are employed. The unfactored implicit Gauss-Seidel relaxation scheme is used for time marching. The numerical simulation of a natural convective ...

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A sensitive issue in numerical calculations for exterior flow problems, e.g. around airfoils, is the treatment of the far field boundary conditions on a computational domain which is bounded. In this paper we investigate this problem for two–dimensional transonic potential flows with subsonic far field flow around airfoil profiles. We take the artificial far field boundary in the subsonic flow ...

We describe a new spectral multidomain method for the solution of the compressible Navier-Stokes equations. Within each subdomain, the method collocates the solution unknowns and the gradients at the nodes of the Gauss-Chebyshev quadrature. The total fluxes are evaluated at the nodes of the Gauss-Lobatto quadrature. Both conforming and non-conforming subdomain grids are allowed. Two examples ar...

A study is made of the influence of the longitudinal magnetic field and density inhomogeneity on the supersonic shear flow instability at the magnetospheric tail boundary. It is shown that the most unstable are slow oblique (3D) disturbances, with a phase velocity approaching at a sufficiently large angle (with respect to the flow direction) the magnetosonic velocity. Their growth rate and spec...

We highlight the necessity for evaluating and evolving the global axisymmetric radial electric field in a tokamak consistent with conservation of toroidal angular momentum for both € δf and full f gyrokinetic codes, where f is the full distribution function and € δf its departure from Maxwellian. We also consider the effects of a strong radial electric field in a subsonic pedestal in the banana...

We have studied the fate of initial magnetic fields in the hot halo gas out of which the visible parts of galaxies form, using threedimensional numerical MHD-experiments. The halo gas undergoes compression by several orders of magnitude in the subsonic cooling flow that forms the cold disk. The magnetic field is carried along and is amplified considerably in the process, reaching μG levels for ...

The efficient direct optimization method is developed for aerodynamic shapes design at subsonic and supersonic flow regimes. The method combines Newton based algorithm with CFD modeling and is capable of handling large number of design variables. Aerodynamic drag is considered as the objective function minimized under volume and overall dimensions constraints. The efficiency of the method is de...