An algorithm for unsteady flows with strong convection

An implicit ADI numerical method for the calculation of 2-D unsteady flows with strong convection effects is described. The method is based on the conventional Crank-Nicholson approach for parabolic equations but an upwind-downwind differencing is used for the first order spatial derivatives associated with convection. The differencing is carried out in the current and previous time plane in such a way that the algorithm is second order accurate in both space and time. The difference equations are factored into sequential operators, one in each independent spatial variable; the solution at each time step may then be computed as a sequence of tridiagonal matrix problems. The method may be used in a noniterative manner although iteration at each time step is recommended in situations where the effects of convection are strong

Analysis of complex singularities in high-Reynolds-number Navier-Stokes solutions

Numerical solutions of the laminar Prandtl boundary-layer and Navier-Stokes equations are considered for the case of the two-dimensional uniform flow past an impulsively-started circular cylinder. We show how Prandtl's solution develops a finite time separation singularity. On the other hand Navier-Stokes solution is characterized by the presence of two kinds of viscous-inviscid interactions that can be detected by the analysis of the enstrophy and of the pressure gradient on the wall. Moreover we apply the complex singularity tracking method to Prandtl and Navier-Stokes solutions and analyze the previous interactions from a different perspective

Mechanical principles and retention of the elementary back stroke

The purpose of this study was to investigate the difference, if any, in skill retention of students learning the elementary back stroke under two differing conditions. Both groups were taught by the demonstration, explanation, practice with correction method. The experimental group, in addition, was taught the mechanical principles governing the stroke. Subjects were 35 men and women students enrolled in two beginning swimming classes at the University of North Carolina at Greensboro. Both classes were given elementary water skills before the study began. Then both were taught the elementary back stroke for this investigation, with the experimental group also instructed in the mechanical principles applicable to the stroke. The Rosentswieg Revision of the Power Test was given after the 3¼ weeks of instruction on the stroke and again 6 weeks later, after a period of no practice on the elementary back stroke. An analysis of covariance and Fisher's "t" test for small uncorrelated groups were the statistical methods used to determine if there were a difference in retention scores

Viscous-Inviscid Interactions in a Boundary-Layer Flow Induced by a Vortex Array

In this paper we investigate the asymptotic validity of boundary layer theory. For a flow induced by a periodic row of point-vortices, we compare Prandtl's solution to Navier-Stokes solutions at different $Re$ numbers. We show how Prandtl's solution develops a finite time separation singularity. On the other hand Navier-Stokes solution is characterized by the presence of two kinds of viscous-inviscid interactions between the boundary layer and the outer flow. These interactions can be detected by the analysis of the enstrophy and of the pressure gradient on the wall. Moreover we apply the complex singularity tracking method to Prandtl and Navier-Stokes solutions and analyze the previous interactions from a different perspective

A Faculty-Guided Continuous-Improvement Regimen With ABET Student-Outcome Scaffolding

Every ABET-accredited program must satisfy Criterion 4, which requires that programs carry out regular, documented procedures for assessing and promoting student attainment in its designated ABET Student Outcomes (SOs). These procedures are collectively denoted "Continuous Improvement" (CI). This paper describes a practical CI regimen which utilizes faculty SO oversight committees, one for each ABET-designated SO. Each three-to-four member SO committee has broad oversight responsibility for student attainment in its respective SO, including assessments, evaluations, and curricular recommendations. This CI regimen has both engaged the faculty and enhanced our Program's alignment with its designated ABET Student Outcomes