An experimental and numerical investigation of heat transfer enhancement in a three dimensional channel using wall mounted porous baffles was conducted. The module average heat transfer coefficients were measured in a uniformly heated rectangular channel with staggered positioned porous baffles. A numerical procedure was implemented, in conjunction with a commercially available Navier-Stokes solver, to model the turbulent flow in porous media. The Brinkman-Forchheimer-Extended Darcy model was used for modeling fluid flow through the porous baffles. Conventional, oneequation, and two-equation models were used for heat transfer modeling. The accuracy and characteristics of each model were investigated and discussed. The results were compared with experimental data. Baffles were mounted alternatively on the top and bottom walls. Heat transfer coefficients and pressure loss for periodically fully developed flow and heat transfer were obtained for different pore densities (10, 20, and 40 pores per inch (PPI)) with two different baffle heights ( / h h B D = 1/3 and 2/3), and two baffle thicknesses ( / t h B D = 1/3 and 1/12). The Reynolds number (Re) was varied from 20,000 to 50,000. To compare the effect of foam metal baffles, the data for conventional solid-type baffles was obtained for ( / t h B D =1/3). The maximum uncertainties associated with the module Nusselt number and friction factor were 5.8% and 4.3%, respectively. The experimental procedure was validated by comparing the data for the straight channel without baffles ( / h h B D = 0) with those in the literature. The use of porous baffles resulted in heat transfer enhancement as high as 300% compared to heat transfer in straight channels without baffles. However, the heat transfer enhancement per unit increase in pumping power was less than one for the range of parameters studied in this work. Correlation equations were developed for the heat transfer enhancement ratio and the heat transfer enhancement per unit increase in pumping power in terms of Reynolds number. The conventional theoretical model, the dispersion conductivity model, and the modified two-phase model using the local thermal non-equilibrium theory were considered. The results from each model were compared against the experimental data, and compared to each other to investigate the efficiency of each model. Also, the characteristics of each model were discussed.

There are several reasons for reducing particulate formation as a result of combustion processes and to date, a number of approaches have been proposed to numerically predict soot. There is a trade-off between accuracy and computational cost and processing time. Two equation semi-empirical models have been used, with some success, to reconcile the need for fast solution turn around and accuracy. However, these models do not account for the mass balance between the gas phase and soot. In this study, the effects of mass conservation of the soot precursors in the gas phase were investigated in an ethylene-air laminar flame simulation at atmospheric pressure. Soot formation was predicted with a two-equation model. Then the model was modified for predicting soot in a turbulent ethylene-air flame operating at 1 atm. The new model is a [2+1]-equation model which accounts for the mass conservation of soot precursors.

There are several reasons for reducing particulate formation as a result of combustion processes and to date, a number of approaches have been proposed to numerically predict soot. There is a trade-off between accuracy and computational cost and processing time. Two equation semi-empirical models have been used, with some success, to reconcile the need for fast solution turn around and accuracy. However, these models do not account for the mass balance between the gas phase and soot. In this study, the effects of mass conservation of the soot precursors in the gas phase were investigated in an ethylene-air laminar flame simulation at atmospheric pressure. Soot formation was predicted with a two-equation model. Then the model was modified for predicting soot in a turbulent ethylene-air flame operating at 1 atm. The new model is a [2+1]-equation model which accounts for the mass conservation of soot precursors.

This thesis presents the implementation of several two-equation turbulence models into a finite difference, two- and three-dimensional Navier-Stokes Solver. Theories of turbulence modeling and the historical development of these theories are briefly investigated. Turbulence models that are defined by two partial differential equations, based on k-&amp / #969 / and k-&amp / #949 / models, having different correlations, constants and boundary conditions are selected to be adapted into the base solver. The basic equations regarding the base Navier-Stokes solver to which the turbulence models are implemented presented by briefly explaining the outputs obtained from the solver. Numerical work regarding the implementation of turbulence models into the base solver is given in steps of non-dimensionalization, transformation of equations into generalized coordinate system, numerical scheme, discretization, boundary and initial conditions and limitations. These sections of implementation are investigated and presented in detail with providing every steps of work accomplished. Certain trial problems are solved and outputs are compared with experimental data. Solutions for fluid flow over flat plate, in free shear, over cylinder and airfoil are demonstrated. Airfoil validation test cases are analyzed in detail. For three dimensional applications, computation of flow over a wing is accomplished and pressure distributions from certain sections are compared with experimental data.

Turbulent dynamics at two sites (C and D) in a hypoxic zone on the Texas- Louisiana continental shelf were studied by investigating turbulence quantities i.e. turbulence kinetic energy (TKE), dissipation rate of TKE (E), Reynolds stress (τ ), dissipation rate of temperature variance (χ), eddy diffusivity of temperature (ν't), and eddy diffusivity of density (ν'p). Numerical models were also applied to test their capability of simulating these turbulence quantities. At site D, TKE, E, and τ were calculated from velocity measurements in the bot- tom boundary layer (BBL), using the Kolmogorov’s -5/3 law in the inertial subrange of energy spectra of vertical velocity fluctuations in each burst measurement. Four second-moment turbulence closure models were applied for turbulence simulations, and modeled turbulence quantities were found to be consistent with those observed. It was found from inter-model comparisons that models with the stability functions of Schumann and Gerz predicted higher values of turbulence quantities than those of Cheng in the mid layer, which might be due to that the former stability functions are not sensitive to buoyancy. At site C, χ, E, v’t, and ν’p were calculated from profile measurements throughout the water column, and showed high turbulence level in the surface boundary layer and BBL, as well as in the mid layer where shear stress was induced by advected non-local water above a hypoxic layer. The relatively high dissolved oxygen in the non-local water resulted in upward and downward turbulent oxygen fluxes, and the bottom hypoxia will deform due to turbulence in 7.11 days. Two of the four models in the study at site D were implemented, and results showed that turbulence energy resulting from the non-local water was not well reproduced. We attribute this to the lack of high-resolution velocity measurements for simulations. Model results agreed with observations only for χ and E simulated from the model with the stability function of Cheng in the BBL. Discrepancies between model and observational results lead to the following conclusions: 1) the stability functions of Schumann and Gerz are too simple to represent the turbulent dynamics in stratified mid layers; 2) detailed velocity profiles measurements are required for models to accurately predict turbulence quantities. Missing such observations would result in underestimation,

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / In Canada taxpayers have an opportunity to save on their taxes through a program entitled the Registered Retirement Saving Plan, one of the most important tax deferred savings vehicles offered. RRSPs were first introduced in Canada in 1957. The contribution limits were increased substantially in the early 1970s, and RRSPs were widely promoted. Since then, they have become a prominent form of Canadian saving. RRSP contributions now exceed the total of employee and employer contributions to employer-provided pension plans (Revenue Canada, Tax Statistics on Individuals, Edition 1998). The RRSP option is especially attractive considering that the Canada Pension Plan, historically responsible for providing retirement benefits to all Canadians over age 65 when they retire, is in a precarious situation due to demographic changes. These factors would have us believe that a large number of Canadians take advantage of the RRSP program to save on their taxes, as well as to assure their old ages with a sufficient level of wealth. In fact, only one-third of Canadian families ^A4^o had access to the RRSP option contributed to such a plan in 1997 (Globe and Mail, March 1998, Calculations using data from Statistics Canada). u This paper describes a model for predicting the outcome of the RRSP decision making process for households. In this paper, we will explore a two-equation model for estimating households' behavior toward the decision to contribute in a RRSP and the amount of contribution. Our approach will integrate two groups of characteristics of households : one being demographic with age, gender, family size, location, education, and marital status and the other being financial with income, pension, debt and non liquid assets. We expect our empirical results to be consistent with previous researches based on the Individual Retirement Account (IRA), the American alter ego of the Canadian Registered Retirement Saving Plan (RRSP). 0 The main purpose of this paper is to develop a model that demonstrates a framework of Canadian households' behavior regarding their decisions to contribute to their own retirement wealth. It is still very early to draw conclusions about the households decisions and behaviors because the government is stilt very present as a source of retirement income. However, it is helpful to observe contemporary trends in order to determine the means of improving the information given to the general population regarding RRSPs.