Table of contents

Seeking a method for checking the results of numerical calculations, we reviewed the series-expansion method in order to take advantage of its simplicity and analytical exactness. For the first step we reformed and revised Oswatitsch and Rothstein's method, which is characterized by the direct use of mass flow conditions and can easily be applied to the analysis of nozzle flow of any configuration.

The influence of dissipation at the modular four segment wavemaker and at the solid walls, on the evolution of sloshing waves in the vicinity of the second cut-off frequency in a rectangular tank, was studied both experimentally and theoretically. Experiments were performed at two different geometries of the wavemaker with correspondingly different dissipation rates. The conclusions regarding the importance of the dissipation rate at the wavemaker could thus be drawn. A model which allows to incorporate dissipation in the governing equation and in the wavemaker boundary condition, is presented. The actual values of the dissipation coefficients at the wavemaker were chosen by realizing the importance of the vortex shedding at the edges of the solid surfaces of the modular wavemaker. Stationary and modulated regimes were obtained both experimentally and numerically by varying the value of the detuning parameter.

The mixed convection boundary layer on a vertical flat plate for uniform wall temperature/uniform heat flux is investigated using computer extension of perturbation series. The first thirteen terms for the uniform wall temperature case and the first ten terms for the uniform heat flux case are computed. The expansion, when transformed by Euler transform and other techniques, predicts the exact results to three-digit accuracy for all values of the streamwise coordinate, ξ, along the plate. For uniform wall temperature, the maximum error is 0.0087% for skin-friction and 0.00065% for heat-transfer. For uniform heat flux, the maximum error is 1.027% for skin-friction and 0.288% for wall temperature.

A subsonic experimental study has been conducted to examine the mean and turbulent properties of a single longitudinal vortex generated by a half-delta wing. Measurements were made on fine cross-plane grids at seven streamwise locations using hot cross-wires. The evaluated streamwise vorticity contours indicated that the initially distorted vortex at a streamwise station equivalent to a half wing height became round by about three wing heights. In this initial "transition" region, where the vortex was still rolling-up, the peak vorticity dropped by about 50% following a X^-1/2 decay. In this region, the generator wake remained distinct from the region of maximum vorticity, although the two regions were seen to slowly merge together. The Reynolds stress contours were also distorted initially with the maximum values occurring in the generator wake region, rather than in the vortex core, but these also decayed rapidly. Downstream of the transition region, the vortex appeared to reach an equilibrium state with the regions of maximum vorticity and turbulent kinetic energy coincident and the levels approximately constant with increasing streamwise distance. Comparison with previous data on vortices produced by double-branched generators further confirmed that the present vortex had achieved a fully developed state, and in a relatively short streamwise distance.

Pressure-flow relationships are derived for the steady flow through an eccentric double circular tube whose cross section takes the form of an annulus bounded by two circles which are in general not concentric. The velocity distribution can be obtained by solving a two-dimensional Poisson equation with the use of conformal mapping. In a case when the two circles touch, a mapping function of different type is required to solve the equation. The relationships thus derived are reduced to the well-known formula for the limit of concentric circles. It is found that when the region between touching circles becomes sufficiently thin, the tube conductance behaves like the cube of the difference of radii of the two circles.