The recent resurgence in hypersonics is centered around the development of SCRAMJET engine technology to power future hypersonic vehicles. Successful flight trials by Australian and American scientists have created interest in the scramjet engine research across the globe. To develop scramjet engine, it is important to study heat transfer effects on the engine performance and aerodynamic forces acting on the body. Hence, the main aim of present investigation is the design of scramjet engine configuration and measurement of aerodynamic forces acting on the model and heat transfer rates along the length of the combustor. The model is a two-dimensional single ramp model and is designed based on shock-on-lip (SOL) condition. Experiments are performed in IISc hypersonic shock tunnel HST2 at two different Mach numbers of 8 and 7 for different angles of attack. Aerodynamic forces measurements using three-component accelerometer force balance and heat transfer rates measurements using platinum thin film sensors deposited on Macor substrate are some of the shock tunnel flow diagnostics that have been used in this study.

This thesis studies advection modeling for heat transfer and fluid flow problems using a new Non--Inverted Skew Upwind Scheme (called NISUS). Variants of the new scheme are formulated and developed with 8-noded hexahedral elements using the Finite Element Method (FEM)and rectangular elements based on a Finite Volume Method (FVM). A new method of mass weighting to predict convective fluxes of each scalar from the nodal point values is developed. Due to an explicit representation in terms of nodal variables, local inversion of the upwind coefficient matrix is not needed. Also, this thesis evaluates two variants of the new scheme (i.e., 3-node / 3-point and 4-node / 8-point formulations) within a 3--D FEM and a third variant within a 2--D FVM. The 3--D FEM variants are applied to a variety of test problems involving the transport of a scalar variable, while the 2--D FVM variant is applied to fluid flow problems including natural convection in an enclosure and micro--channel flow simulations. The promising performance of NISUS, as compared with exact and previous solutions, is demonstrated both in terms of accuracy and stability. Furthermore, a new data storage format called Compressed Banded Data (CBD) is developed for sparse banded matrices generated by the control volume finite element method (CVFEM). The platform of the new CBD structure permits dynamic switching between various solvers, without any procedural change in the implementation of existing simulation software. The performance of different Krylov techniques with an ILU(0) preconditioner is observed and compared in three test problems with a direct solver. / October 2006

Climate models are the primary tools used for understanding past climate variations and for future projections. The atmospheric radiation is the key component of these models. Accurate modeling of atmosphere necessitates reliable evaluation of the medium radiative properties and accurate solution of the radiative transfer equation in conjunction with the time-dependent multi-dimensional governing equations of atmospheric models. Due to difficulty in solving the equations of atmospheric and radiation models simultaneously, radiation equations have been solved when input data such as concentration, temperature etc. were made available upon solution of equations of atmospheric models. Generally, time step of conservation equations are 10-30 minutes but radiative transfer equation is called only once every 1-3 hours. However, there is inaccuracy due to the fixed radiation fluxes over the intervening time steps. To overcome this problem, the equations of atmospheric and radiation models have to be solved simultaneously and the solution methods have to be compatible. For this purpose, a radiative-convective model with radiation model based on method of lines (MOL) solution of discrete ordinate method (DOM) with wide band correlated-k (WBCK) was developed. To achieve this objective, a previously developed MOL solution of DOM with WBCK model was adapted to 1-D longwave clear sky atmosphere and its predictive accuracy and computational efficiency was examined on the test problem by using benchmark solution obtained from Line-by-line Radiative Transfer Model (LBLRTM). The radiation code was then coupled with radiative-convective model and the predictive accuracy of this model was examined for several coupling intervals. Comparisons reveal that as coupling interval increases, although the computation time of the model decreases, the predicted temperature profiles diverge from the one obtained when equations of radiative-convective model and the radiation model are solved simultaneously and percentage relative error in temperature increases an order of magnitude when coupling time between radiative-convective model and the radiation model increases from 2 to 10 hours. Therefore, it can be concluded that the equations of the radiation model have to be solved simultaneously with the equations of the climate model. Overall evaluation of the performance of the radiation model used in this study points out that it provides accurate and computationally efficient solutions and can be used with confidence in conjunction with the climate models for simultaneous solution of governing equations with radiation transfer equation.

L'étude ici développée traite de deux aspects de la microfluidique : l'hydrodynamique d'écoulements liquides en microtubes et l'ébullition convective en minicanaux. Le dispositif et la méthode de traitement développés dans la première partie du mémoire permettent d'obtenir le nombre de Poiseuille d'écoulements laminaires liquides avec une précision inférieure à 4%. L'étude met en évidence une croissance du nombre de Poiseuille pour les écoulements d'eau distillée, d'eau de ville et des solutions de KCl au sein de microtubes en silice de diamètres allant de 540 à 52 µm. L'origine des écarts à la théorie classique en macroconduites a été recherchée. Une des hypothèses vraisemblable est l'effet de la Double Couche Electrique due aux ions contenus dans le fluide et à la surface interne du microtube chargée électrostatiquement. Dans la seconde partie du manuscrit, nous mettons en évidence l'influence du confinement pariétal sur un écoulement avec changement de phase liquide-vapeur au sein d'un minicanal vertical. Deux régimes d'ébullition sont observés : stationnaire avec des structures d'écoulements classiques et instationnaires dues à une production importante de vapeur. Dans ce dernier cas, nous distinguons les fluctuations de couplage et les fluctuations intrinsèques à l'écoulement confiné. Un critère de déclenchement des instationarités permet d'accéder à une grandeur adimensionnelle. Une loi d'échelle est alors proposée pour les écoulements diphasiques dans les minicanaux. Il en est de même pour les transferts thermiques.

Failure to maintain thermal equilibrium can cause uncontrollable increases in body core temperature beyond critical upper limits. In selecting clothing, consideration must be given to the heat transfer properties of clothing that may restrict the cooling capacity of the human body under heat stress conditions, most importantly, apparent total evaporative resistance (Re,T,a). This study calculated and compared Re,T,a for five clothing ensembles under varying heat stress conditions, including three relative humidity (RH) levels and three stages of heat stress to determine if Re,T,a values varied or remained the same with changes in heat stress conditions. A four-way mixed model analysis of variance demonstrated significant differences for estimated Re,T,a values among ensembles, RH levels, heat stress stages, and interactions among ensembles and RH levels and ensembles and heat stress stages (p < 0.0001). No significant interaction among RH levels and heat stress stages was found (p = 0.67). A Tukey's Honestly Significant Difference multiple comparison test was used to identify where significant differences occurred (p < 0.05). The results of the study indicated that Re,T,a values do change with RH levels and stages of heat stress and that the theoretical framework for explaining heat-exchange in hot environments is not yet well-established. Also confirmed was the dominance of the convection pathway over the diffusion pathway in hot environments.

<p>Accurate modeling of land-atmosphere interaction would help us understand the persistent weather conditions and further contribute to the skill of seasonal climate prediction. In this study, seasonal variations in radiation and precipitation forcing are included in a stochastic soil water balance model to explore the seasonal evolution of soil moisture probabilistic structure. The theoretical results show soil moisture tends to exhibit bimodal behavior only in summer when there are strong positive feedback from soil moisture to subsequent rainfall. Besides the statistical analysis of soil moisture – rainfall feedback, simplified mixed-layer models, coupled with soil-plant-atmosphere continuum, are also used to study heat flux partitioning, cloud initiation, and strength of moist convection. Approximate analytical solutions to the mixed-layer model are derived by applying Penman-Monteith approach, which help explain the roles of equilibrium evaporation and vapor pressure deficit in controlling the diurnal evolution of boundary layer. Results from mixed-layer model also define four regimes for possible convection in terms of cloud/no-cloud formation and low/high convection intensity. Finally, cloud-topped mixed-layer model is developed to simulate the boundary-layer dynamics after the cloud formation, when the evaporative and radiative cooling other than surface heat flux may significantly contribute to the growth of the boundary layer.</p> / Dissertation

High interstitial fluid pressure (IFP) in tumours is recognized as a barrier to drug delivery resulting in reduced efficacy. High IFP impedes the normal process of convective fluid flow (CFF) from blood vessels into the interstitium. The aim of this study was to develop an in vitro model that could be used to measure CFF and to study its effects on drug delivery. The model consists of a transwell cell culture insert which supports the growth of multicell layers (MCL) on collagen coated membranes. A graduated tube is inserted into the transwell and a pressure gradient is applied across the membrane by raising the volume of medium in the tube above that of the bottom chamber. CFF is determined by measuring the weight of medium in the bottom chamber as a function of time. CFF was inversely proportional to MCL thickness and 41.1±3.6µm thick MCL has completely stopped CFF. Using a physiologically relevant hydrostatic pressure of 28mmHg, a CFF of 21µL/min was recorded using a DLD-1 MCL that was 12.21±3.2µm thick. Under these conditions, the rates of penetration of doxorubicin, imatinib and gefitinib were respectively 42, 26 and 13 folds greater than when no CFF exists. Reversing the CFF so that it opposed the drug diffusion gradient significantly impairs drug penetration. In conclusion, a novel in vitro model for assessing the impact of CFF on drug delivery has been developed. This model could be used to evaluate strategies designed to increase drug delivery to solid tumours by modifying the CFF.

The Madden-Julian Oscillation (MJO), a tropical phenomenon that exists on the time scale of 30-90 days, commonly initiates over the Indian Ocean and slowly propagates into the western Pacific as a series of convective events, which have time scales on the order of hours or days. These events and the overall MJO convective envelope may interact with convectively coupled waves such as Kelvin waves that propagate more rapidly eastward with time scales of 3-5 days. Radar and sounding data collected during the DYNAMO/AMIE/CINDY2011 field campaign from October 2011 to February 2012 in the central Indian Ocean are used to study the interaction between Kelvin waves and the MJO in terms of atmospheric and cloud properties. The focus is on characterizing the precipitation characteristics, convective cloud spectrum, and atmospheric profiles of Kelvin waves during the active and suppressed phases of the MJO to gain insight on MJO initiation. Characteristics of waves identified using different satellite thresholds and filtering methods are compared. Composites of the radar and sounding observations are calculated for a total of ten Kelvin waves and three MJO events that occurred during the field campaign. Analyzed radar products include convective-stratiform classification of rain rate, rain area, and echo-top heights, as well as cloud boundaries. Sounding data includes profiles of wind speed and direction and relative humidity. Kelvin waves that occur during the suppressed MJO are convectively weaker than Kelvin waves during the active MJO, but display previously documented structure of low-level convergence and a moist atmosphere prior to the wave passage. During the active MJO, Kelvin waves have stronger convective and stratiform rain, and the entire event is longer, suggesting a slower moving wave. The Kelvin wave vertical structure is somewhat overwhelmed by the convective envelope associated with the MJO. When the MJO is developing, the Kelvin wave displays a moisture-rich environment after the passage, providing deep tropospheric moisture that is postulated to be important for the onset of the MJO. The convective cloud population prior to MJO initiation shows increased moisture and a population of low- to mid-level clouds. The moisture precedes shallow convection, which develops into the deep convection of the MJO, supporting the discharge-recharge theory of MJO initiation. Additionally, enhanced moisture after the passage of the pre-MJO Kelvin wave could also support the frictional Kelvin-Rossby wave-CISK theory of MJO initiation. With a better understanding of the interaction between the initiation of the MJO and Kelvin waves, the relationships between the environment and the onset of the convection of the MJO can be improved.

This thesis studies advection modeling for heat transfer and fluid flow problems using a new Non--Inverted Skew Upwind Scheme (called NISUS). Variants of the new scheme are formulated and developed with 8-noded hexahedral elements using the Finite Element Method (FEM)and rectangular elements based on a Finite Volume Method (FVM). A new method of mass weighting to predict convective fluxes of each scalar from the nodal point values is developed. Due to an explicit representation in terms of nodal variables, local inversion of the upwind coefficient matrix is not needed. Also, this thesis evaluates two variants of the new scheme (i.e., 3-node / 3-point and 4-node / 8-point formulations) within a 3--D FEM and a third variant within a 2--D FVM. The 3--D FEM variants are applied to a variety of test problems involving the transport of a scalar variable, while the 2--D FVM variant is applied to fluid flow problems including natural convection in an enclosure and micro--channel flow simulations. The promising performance of NISUS, as compared with exact and previous solutions, is demonstrated both in terms of accuracy and stability. Furthermore, a new data storage format called Compressed Banded Data (CBD) is developed for sparse banded matrices generated by the control volume finite element method (CVFEM). The platform of the new CBD structure permits dynamic switching between various solvers, without any procedural change in the implementation of existing simulation software. The performance of different Krylov techniques with an ILU(0) preconditioner is observed and compared in three test problems with a direct solver.

This thesis studies advection modeling for heat transfer and fluid flow problems using a new Non--Inverted Skew Upwind Scheme (called NISUS). Variants of the new scheme are formulated and developed with 8-noded hexahedral elements using the Finite Element Method (FEM)and rectangular elements based on a Finite Volume Method (FVM). A new method of mass weighting to predict convective fluxes of each scalar from the nodal point values is developed. Due to an explicit representation in terms of nodal variables, local inversion of the upwind coefficient matrix is not needed. Also, this thesis evaluates two variants of the new scheme (i.e., 3-node / 3-point and 4-node / 8-point formulations) within a 3--D FEM and a third variant within a 2--D FVM. The 3--D FEM variants are applied to a variety of test problems involving the transport of a scalar variable, while the 2--D FVM variant is applied to fluid flow problems including natural convection in an enclosure and micro--channel flow simulations. The promising performance of NISUS, as compared with exact and previous solutions, is demonstrated both in terms of accuracy and stability. Furthermore, a new data storage format called Compressed Banded Data (CBD) is developed for sparse banded matrices generated by the control volume finite element method (CVFEM). The platform of the new CBD structure permits dynamic switching between various solvers, without any procedural change in the implementation of existing simulation software. The performance of different Krylov techniques with an ILU(0) preconditioner is observed and compared in three test problems with a direct solver.