A computer program to calculate radiating viscous stagnation streamline flow with strong blowing

A computer program (program LEE) has been developed to calculate the fully coupled solution of the radiating viscous stagnation streamline flow with strong blowing. The report describes the digital computer program, including FORTRAN IV listing, flow charts, instructions for the user, and a test case with input and output. Program LEE is available through COSMIC

Goertler instability in compressible boundary layers along curved surfaces with suction and cooling

The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two-dimensional boundary layers are presented in an orthogonal curvilinear coordinate. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for 0 to 5. The effect of wall cooling and suction of the boundary layer on the development of Goertler vortices is investigated for different Mach numbers

Executing matrix multiply on a process oriented data flow machine

The Process-Oriented Dataflow System (PODS) is an execution model that combines the von Neumann and dataflow models of computation to gain the benefits of each. Central to PODS is the concept of array distribution and its effects on partitioning and mapping of processes.In PODS arrays are partitioned by simply assigning consecutive elements to each processing element (PE) equally. Since PODS uses single assignment, there will be only one producer of each element. This producing PE owns that element and will perform the necessary computations to assign it. Using this approach the filling loop is distributed across the PEs. This simple partitioning and mapping scheme provides excellent results for executing scientific code on MIMD machines. In this way PODS allows MIMD machines to exploit vector and data parallelism easily while still providing the flexibility of MIMD over SIMD for multi-user systems.In this paper, the classic matrix multiply algorithm, with 1024 data points, is executed on a PODS simulator and the results are presented and discussed. Matrix multiply is a good example because it has several interesting properties: there are multiple code-blocks; a new array must be dynamically allocated and distributed; there is a loop-carried dependency in the innermost loop; the two input arrays have different access patterns; and the sizes of the input arrays are not known at compile time. Matrix multiply also forms the basis for many important scientific algorithms such as: LU decomposition, convolution, and the Fast-Fourier Transform.The results show that PODS is comparable to both Iannucci's Hybrid Architecture and MIT's TTDA in terms of overhead and instruction power. They also show that PODS easily distributes the work load evenly across the PEs. The key result is that PODS can scale matrix multiply in a near linear fashion until there is little or no work to be performed for each PE. Then overhead and message passing become a major component of the execution time. With larger problems (e.g., >/=16k data points) this limit would be reached at around 256 PEs