DG for Compressible Inviscid and Viscous Flows with a Large Range of Mach Numbers

2008 ◽  
Author(s):  
Václav Kučera ◽  
Miloslav Feistauer
Keyword(s):  
Large Range ◽  
Viscous Flows ◽  
Mach Numbers

scholarly journals A Preconditioned Method for Rotating Flows at Arbitrary Mach Number

2011 ◽  
Vol 2011 ◽  
pp. 1-17 ◽  
Author(s):  
Chunhua Sheng
Keyword(s):  
Mach Number ◽  
Current Method ◽  
Viscous Flows ◽  
Original Method ◽  
Superior Performance ◽  
Governing Equations ◽  
Free Stream Mach Number ◽  
Rotating Frames ◽  
Mach Numbers ◽  
Diffusive Fluxes

An improved preconditioning is proposed for viscous flow computations in rotating and nonrotating frames at arbitrary Mach numbers. The key to the current method is the use of both free stream Mach number and rotating Mach number to construct a preconditioning matrix, which is applied to the compressible governing equations written in terms of primitive variables. A Fourier analysis is conducted that reveals the efficacy of the modified preconditioning. Numerical approximations for the convective and diffusive fluxes are detailed based on the preconditioned system of equations. A set of boundary conditions using characteristic variables are described for internal and external flow computations. Numerical validations are performed on four realistic viscous flows in both fixed and rotating frames. The results indicated that the modified preconditioning has a superior performance compared to the original method to predict flows from extremely low to supersonic Mach numbers.

scholarly journals ANALYTIC SOLUTIONS FOR TRUNCATED PLASMONS

2021 ◽  
Vol 57 (1) ◽  
pp. 181-188
Author(s):  
J. Cantó ◽  
A. C. Raga
Keyword(s):  
Mach Number ◽  
Large Range ◽  
Analytic Solutions ◽  
Gas Pressure ◽  
Width Ratio ◽  
Environmental Pressure ◽  
Mach Numbers

We present a new plasmon model for a cometary clump moving supersonically in an environment with a non-zero gas pressure. We find that the environmental pressure produces a cutoff in the wings of the cometary clump, therefore resulting in quite "stubby" plasmons for a large range of flow Mach numbers. We derive a relation between the length-to-width ratio of the plasmon and the Mach number M of the flow, which could be used to directly derive M from observations of (appropriate) cometary clumps.

Small Computer System for Micrograph Analysis

1981 ◽  
Vol 39 ◽  
pp. 270-271
Author(s):  
J. F. Hainfeld ◽  
J. S. Wall
Keyword(s):  
Large Range ◽  
Small Computer ◽  
Black And White ◽  
Contour Maps ◽  
Points Of Interest ◽  
Computer Aided Analysis ◽  
Specialized Hardware ◽  
Additional Memory ◽  
Selection Of ◽  
Publication Quality

Cost reduction and availability of specialized hardware for image processing have made it reasonable to purchase a stand-alone interactive work station for computer aided analysis of micrographs. Some features of such a system are: 1) Ease of selection of points of interest on the micrograph. A cursor can be quickly positioned and coordinates entered with a switch. 2) The image can be nondestructively zoomed to a higher magnification for closer examination and roaming (panning) can be done around the picture. 3) Contrast and brightness of the picture can be varied over a very large range by changing the display look-up tables. 4) Marking items of interest can be done by drawing circles, vectors or alphanumerics on an additional memory plane so that the picture data remains intact. 5) Color pictures can easily be produced. Since the human eye can detect many more colors than gray levels, often a color encoded micrograph reveals many features not readily apparent with a black and white display. Colors can be used to construct contour maps of objects of interest. 6) Publication quality prints can easily be produced by taking pictures with a standard camera of the T.V. monitor screen.

Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel

1985 ◽  
Vol 43 ◽  
pp. 52-53
Author(s):  
G. M. Michal ◽  
T. K. Glasgow ◽  
T. J. Moore
Keyword(s):  
Austenitic Steel ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Large Range ◽  
Amorphous Structure ◽  
Nucleation And Growth ◽  
Ni Alloys ◽  
Melt Spun ◽  
Crystal Fibers ◽  
Rapidly Solidified

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.

CALCULATION OF PERIODIC VISCOUS FLOWS INITIATED BY NEAR-WALL BODY FORCE

2016 ◽  
Vol 47 (1) ◽  
pp. 51-63
Author(s):  
Sergey Viktorovich Manuilovich
Keyword(s):  
Body Force ◽  
Viscous Flows ◽  
Near Wall

Efficient approach for analysis of unsteady viscous flows in turbomachines

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 2005-2012
Author(s):  
L. He ◽  
W. Ning
Keyword(s):  
Viscous Flows ◽  
Efficient Approach
Sign in / Sign up

Export Citation Format

Share Document