High accuracy flow simulations: Advances and challenges for future needs in aeronautics

The regularized lattice BGK (RLBGK) is validated against high-accuracy spectral Chebyshev methods for lid-driven cavity flows. RLBGK is shown to provide a viable alternative to standard lattice BGK schemes, with significant enhancement of numerical stability at a very moderate computational extra-cost.

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A HIGH ACCURACY LERAY-DECONVOLUTION MODEL OF TURBULENCE AND ITS LIMITING BEHAVIOR

Analysis and Applications ◽

10.1142/s0219530508001043 ◽

2008 ◽

Vol 06 (01) ◽

pp. 23-49 ◽

Cited By ~ 31

Author(s):

WILLIAM LAYTON ◽

ROGER LEWANDOWSKI

Keyword(s):

Weak Solutions ◽

Stokes Equations ◽

High Accuracy ◽

Navier Stokes ◽

Simple Extension ◽

Entire Family ◽

Navier Stokes Equations ◽

Limiting Behavior ◽

Flow Simulations ◽

Simulation Based

In 1934, J. Leray proposed a regularization of the Navier–Stokes equations whose limits were weak solutions of the Navier–Stokes equations. Recently, a modification of the Leray model, called the Leray-alpha model, has attracted interest for turbulent flow simulations. One common drawback of the Leray type regularizations is their low accuracy. Increasing the accuracy of a simulation based on a Leray regularization requires cutting the averaging radius, i.e. remeshing and resolving on finer meshes. This article analyzes on a family of Leray type models of arbitrarily high orders of accuracy for a fixed averaging radius. We establish the basic theory of the entire family including limiting behavior as the averaging radius decreases to zero (a simple extension of results known for the Leray model). We also give a more technically interesting result on the limit as the order of the models increases with a fixed averaging radius. Because of this property, increasing the accuracy of the model is potentially cheaper than decreasing the averaging radius (or meshwidth) and high order models are doubly interesting.

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A New 1,000 kV Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061318 ◽

1967 ◽

Vol 25 ◽

pp. 260-261

Author(s):

M. Nishigaki ◽

S. Katagiri ◽

H. Kimura ◽

B. Tadano

Keyword(s):

Electron Microscope ◽

High Voltage ◽

Basic Research ◽

Chromatic Aberration ◽

High Accuracy ◽

Biological Specimen ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

High Voltage Electron

The high voltage electron microscope has many advantageous features in comparison with the ordinary electron microscope. They are a higher penetrating efficiency of the electron, low chromatic aberration, high accuracy of the selected area diffraction and so on. Thus, the high voltage electron microscope becomes an indispensable instrument for the metallurgical, polymer and biological specimen studies. The application of the instrument involves today not only basic research but routine survey in the various fields. Particularly for the latter purpose, the performance, maintenance and reliability of the microscope should be same as those of commercial ones. The authors completed a 500 kV electron microscope in 1964 and a 1,000 kV one in 1966 taking these points into consideration. The construction of our 1,000 kV electron microscope is described below.

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