The aerospace plane design challenge: Credible computational fluid dynamics results

Computational fluid dynamics (CFD) is necessary in the design processes of all current aerospace plane programs. Single-stage-to-orbit (STTO) aerospace planes with air-breathing supersonic combustion are going to be largely designed by means of CFD. The challenge of the aerospace plane design is to provide credible CFD results to work from, to assess the risk associated with the use of those results, and to certify CFD codes that produce credible results. To establish the credibility of CFD results used in design, the following topics are discussed: CFD validation vis-a-vis measurable fluid dynamics (MFD) validation; responsibility for credibility; credibility requirement; and a guide for establishing credibility. Quantification of CFD uncertainties helps to assess success risk and safety risks, and the development of CFD as a design tool requires code certification. This challenge is managed by designing the designers to use CFD effectively, by ensuring quality control, and by balancing the design process. For designing the designers, the following topics are discussed: how CFD design technology is developed; the reasons Japanese companies, by and large, produce goods of higher quality than the U.S. counterparts; teamwork as a new way of doing business; and how ideas, quality, and teaming can be brought together. Quality control for reducing the loss imparted to the society begins with the quality of the CFD results used in the design process, and balancing the design process means using a judicious balance of CFD and MFD

Physical aspects of computing the flow of a viscous fluid

One of the main themes in fluid dynamics at present and in the future is going to be computational fluid dynamics with the primary focus on the determination of drag, flow separation, vortex flows, and unsteady flows. A computation of the flow of a viscous fluid requires an understanding and consideration of the physical aspects of the flow. This is done by identifying the flow regimes and the scales of fluid motion, and the sources of vorticity. Discussions of flow regimes deal with conditions of incompressibility, transitional and turbulent flows, Navier-Stokes and non-Navier-Stokes regimes, shock waves, and strain fields. Discussions of the scales of fluid motion consider transitional and turbulent flows, thin- and slender-shear layers, triple- and four-deck regions, viscous-inviscid interactions, shock waves, strain rates, and temporal scales. In addition, the significance and generation of vorticity are discussed. These physical aspects mainly guide computations of the flow of a viscous fluid

Finiteness of the number of compatibly-split subvarieties

We show that for a Frobenius split variety, there are only finitely many closed subvarieties which are compatibly-split.Comment: 3 page

Entrepreneurship by Alliance

Recent years have seen the introduction of markets and a system of private property rights in China with a view to changing the composition of production and demand and enhancing welfare. Central to the success of these reforms is the rise of entrepreneurship with its potential to set the economy on a higher growth path by supplying the products which consumers need and want, creating new employment opportunities, and introducing new and more efficient technologies of production. But to what extent can we expect to see entrepreneurs in China behaving like their counterparts in the advanced industrial economies of Western Europe, Japan, and the United States? This is the question we address in this chapter. In our view, the reform programme has, indeed, opened up new opportunities for private enterprise activity; but idiosyncrasies of the business environment are at the same time generating novel institutional arrangements in support of entrepreneurs' investments. We agree, therefore, with Herrick and Kindleberger when they assert that "Development ought not to be viewed as a monotonic, stylized path, ever onward and upward, historically established and invariably repeated" (1983, p.62).entrepreneurship;economic growth;economic development;business networking;Western economies

Matrices coupled in a chain. I. Eigenvalue correlations

The general correlation function for the eigenvalues of $p$ complex hermitian matrices coupled in a chain is given as a single determinant. For this we use a slight generalization of a theorem of Dyson.Comment: ftex eynmeh.tex, 2 files, 8 pages Submitted to: J. Phys.