Unmeel B. Mehta

Further comparisons of interactive boundary-layer and thin-layer Navier-Stokes procedures

It is generally accepted that the Navier—Stokes equations correctly represent fluid-flow phenomena. Since the unsteady three-dimensional equations can generally be solved for flows where small-scale fluctuations are unimportant, emphasis has been placed on particular reduced forms such as those appropriate to regions of inviscid flow and boundary layers. In recent years, and with the application of numerical solution procedures in mind, attention has also been paid to the Reynolds-averaged Navier—Stokes equations and various further-reduced forms, including their so-called parabolized forms and the thin-layer Navier—Stokes (TLNS) equations.

Multiprocessing on supercomputers for computational aerodynamics

Little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPS or more) to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. We apply the concept of mul tiple instructions and multiple data (MIMD) through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for devel oping a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor.

Interactive boundary-layer calculations of a transonic wing flow

Results obtained from iterative solutions of inviscid and boundary-layer equations are presented and compared with experimental values. The calculated results were obtained with an Euler code and a transonic potential code in order to furnish solutions for the inviscid flow; they were interacted with solutions of two-dimensional boundary-layer equations having a strip-theory approximation. Euler code results are found to be in better agreement with the experimental data than with the full potential code, especially in the presence of shock waves, (with the sole exception of the near-tip region).