Numerical simulations based on molecular statics are carried out to study nano-scale plastic deformation behavior in thin metal films. Particular attention is devoted to correlating the overall mechanical response and the underlying crystal defect mechanisms during mechanical loading. The simulations are within the two-dimensional framework involving pair molecular interactions in singlecrystal materials. Special modeling features are utilized for studying the formation of dislocations, interface characteristics, and defect interactions. Specific problems investigated in this work include: plastic deformation and tensile fracture in a free-standing film, interface-constrained plasticity in substrate-bonded films, and homogeneous nucleation of dislocations during nanoindentation.

The improved numerical approach is implemented with preconditioned Navier-Stokes solver on arbitrary three-dimensional (3-D) structured multi-block complex flowfield. With the successful application of time-derivative preconditioning, present hybrid finite volume solver is performed to obtain the steady state solutions in compressible and incompressible flows. This solver which combined the adjective upwind splitting method (AUSM) family of low-diffusion flux-splitting scheme with an optimally smoothing multistage scheme and the time-derivative preconditioning is used to solve both the compressible and incompressible Euler and Navier-Stokes equations. In addition, a smoothing procedure is used to provide a mechanism for controlling the numerical implementation to avoid the instability at stagnation and sonic region. The effects of preconditioning on accuracy and convergence to the steady state of the numerical solutions are presented. There are two validation cases and three complex cases simulated as shown in this study. The numerical results obtained for inviscid and viscous two-dimensional flows over a NACA0012 airfoil at free stream Mach number ranging from 0.1 to 1.0E-7 indicates that efficient computations of flows with very low Mach numbers are now possible, without losing accuracy. And it is effectively to simulate 3-D complex flow phenomenon from compressible flow to incompressible by using the advanced numerical methods.

An experimental investigation of heat transfer carried out for a semiannular enclosure. Inner and outer walls of the enclosure were kept at different but constant temperatures. The semiannular enclosure was filled with a CuSO4 - H2SO4 - H2O solution. An electrochemical method has been used for the mass transfer. The purpose of this study is to investigate flows resulting from buoyancy due to a combination of both temperature and concentration gradients in the enclosure. The flow structure in the enclosure was visualized by the shadowgraph technique. Flow visualization photograph showed interesting multi-cell flow structures in the enclosure for the cooperating and opposing thermal and solutal buoyancy. An optical technique is based on the idea that the intensity of the light beam absorbed by the copper sulphate solution is proportional to the solution concentration when the light beam passes through the solution. For each flow regime the mass transfer coefficient across the enclosure was also measured. The ranges of the dimensionless parameters studied in the experimental were Ar = 0.23, k = 2.5, Sc = 1700∼2300, Pr = 6.5 ∼ 7.3, Grt = 104 ∼ 106, N = −15.44 ∼ 6.16, θ = 45°∼90°.

Heat transfer and near-wall flow characteristics in an inherently swirling fan flow, containing rectangular-plate turbulators with 45° and 90° angles of attack, were experimentally investigated. The heat transfer characteristics for uniform flows with the turbulators were also investigated for comparison. Eight heated aluminum plates, installed along a bottom duct-wall, were used as the heat transfer surfaces, which allows the studies of heat transfer variations along the duct and the studies of the relations between the local fluid flows and heat transfer variations. Three-component mean and fluctuating velocities were measured using a laser Doppler velocimetry to obtain the near-wall flow parameters, including the axial mean velocity, axial vorticity and turbulent kinetic energy. The temperatures on the eight heat transfer surfaces were measured using thermocouples to obtain the Stanton number distributions. Results suggest that the rectangular-plate turbulators in fan flows may cause the increases in the near-wall flow parameters and, consequently, augment the heat transfer, especially around the flow reattachment regions. Also, the rectangular-plate turbulator effect on heat transfer augmentation in fan flows may be as attractive as that in uniform flows at the investigated X/H ranges.

Applying the principle of virtual work, the slice element method, and the variational method proposed in this paper, one can derive the governing equation and transversality conditions for the rupture surface of a sliding mass of retaining wall and shallow foundation under several external conditions. The governing equation, transversality, and boundary conditions can be solved by the finite difference method (FDM) proposed in this paper, so that the rupture surface and its associated earth pressure acting on the retaining wall or the ultimate bearing capacity acting on the foundation can be determined effectively. By comparison of our results with those of some well known earth pressure and bearing capacity estimating methods, it can be concluded that determining the earth pressure on a retaining wall or the ultimate bearing capacity of a shallow foundation by using the variational method and FDM proposed in this paper, a logical and reasonable result can be obtained without the necessity of guessing the rupture surface.

This work examines the interesting phenomenon of the generation of harmonics by non-breaking waves over permeable submerged obstacles. Nine model geometries, each with six different porosities, from 0.421 to 0.912, were considered to examine the effects of model width, porosity, and submergence depth on harmonic generation. The results revealed coupled effects on harmonic generation. A modified Ursell number was proposed to analyze experimental data. Almost no harmonic generation occurs at a modified Ursell number of less than five and/or a model width to wavelength ratio of over 1.6. After harmonics have been generated, wave profiles become dimpled, and the energy of the fundamental mode is transferred to higher-frequency components. Furthermore, the higher harmonics become more pronounced as the models widen, the depth of submergence becomes shallower, and model porosity declines.

The governing equations for oblique shock waves and nozzle flows in soap films are formulated based on their very specific property equations. The θ-β-M relation for oblique shock waves and the width-velocity relation for quasi-one-dimensional nozzle flows are presented. The results are similar to those of compressible gases. On short time scales, the analogy of soap films to two-dimensional (2-D) compressible gases with a specific heat ratio of γ = 1.0 that is shown by Wen and Lai [1], Wen, et al. [2] and Chomaz [3] is again demonstrated. The present results supplement the theory of compressible flows in soap films.

The vee-gutter, which was conventionally used in a combustor for flame holding, was re-designed by employing the unsteady Coanda effect to inject fluids periodically into near wake of the vee-gutter. Fluidic targets were developed to induce self-sustained transverse oscillation of slit-jet. The self-sustained oscillating jet was conducted through passages and injected into the near wake of the vee-gutter. The behaviors and frequency characteristics of the slit-jet in the oscillation cavity and the turbulence properties in the wake were studied experimentally in a wind-tunnel by using the smoke-wire flow visualization technique and the hot-wire anemometer. The oscillation frequencies of the presently developed jet-injection vee-gutter were about 25 to 40 times higher than that of the conventionally used fluidic flowmeter. By estimating the Lagrangian integral time scale and employing the Taylor's frozen flow hypothesis, the integral length scales of turbulence fluctuations were calculated. The results showed that the integral length scales of turbulences of the jet-injected vee-gutter were significantly smaller than their counter parts of the conventional vee-gutter, which indicated the effects of vortex stretching induced by the periodic jet injection. The modifications of turbulence properties were presented and discussed.