A four variable constitutive equation was developed utilizing the method first presented by Schneck and Walburn. Spearman rank correlation coefficients were calculated on whole blood samples within a narrow range of hematocrit to investigate further the effect of the various plasma constituents on whole blood viscosity. Viscosity measurements were made on one hundred anticoagulated blood samples of known hematocrit and chemical composition. The constitutive equation was developed using a power law functional form similar to that employed by Schneck and Walburn. This equation contains two parameters, the consistency index and the non-Newtonian index. A computerized multiple regression technique with apparent viscosity as the dependent variable was used to determine the particular form of these parameters. The one, two and three variable models developed confirmed the results of the previous work of Schneck and Walburn. The four variable model included the total lipids in combination with the concentration of total protein minus albumin and hematocrit. Spearman rank correlation coefficients showed the highest correlations between whole blood viscosity and the plasma constituents to be those of the globulins, total protein and fibrinogen. The constitutive equation developed did not show as high a correlation between experimental data and theory as did the Schneck-Walburn three variable model. The addition of a fourth variable did produce a statistically significant increase over the best three variable model of the present study. / M.S.

The Two-Fluid traffic model is a tool used to measure the quality of service in city traffic networks. The model has been calibrated for the central business district of Roanoke, Virginia and the results have been compared to those from various other cities around the world. In addition, the sensitivity of the Two-Fluid model parameters has been studied for different unit trip lengths used in calibration for the Roanoke CBD. The three-unit trip lengths tested were 1-mile, 2-mile, and 3-mile. Statistical analyses led to the conclusion that the model parameters are not significantly different for different trip lengths. Furthermore, parameter sensitivity was also established for three types of driver behavior, specifically, "aggressive," "normal," and "conservative." The two-fluid trends showed that the two-fluid curve corresponding to the aggressive driver fell below those of the normal and conservative drivers for off-peak traffic conditions but began to approach the normal trend during peak period. On the other hand, the conservative trend continuously maintained higher trip time values for any given stop time, as compared to the other two trends. This implies that aggressive driving behavior can decrease travel times during off-peak conditions, but has little effect during peak periods, where surrounding traffic does not allow excessive speed or lane changing. / M.S.

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No description available.

The two-dimensional, confined, laminar flow over a downstream facing step was studied using a finite element, Navier-Stokes equation solver. The weak form of the stationary, incompressible Navier-Stokes equations in primitive variable form was obtained using the conventional Galerkin technique for mixed problems. Biquadratic Lagrange interpolating polynomials were used to construct the basis functions that generated the finite-dimensional subspace containing the approximate solutions to the velocity field, while the pressure field was represented by a discontinuous, piecewise-linear approximation. This particular combination of solution subspaces was previously shown in a mathematically rigorous fashion to yield stable, consistent solutions to the Navier-Stokes equations. The results of the computations were benchmarked against the experimental data of Denham and Patrick, and also compared to earlier calculations by Ecer and Thomas, both of whom utilized alternative, unconventional formulations. These comparisons indicate that with the proper choice of basis functions, a conventional Galerkin scheme can yield results that are in as good and in many cases better agreement with the available experimental data than those of unconventional schemes that rely upon an infusion of artificial dissipation to enhance their numerical stability. The computational algorithm was also used to ascertain the cause of the noticeable lack of development and skewness that characterized the experimental data of Denham and Patrick both at and upstream of the step. The results of this study indicated that as suspected by Denham and Patrick, the skewness as well as the lack of development of the velocity profiles near the step were caused by the geometry of the test apparatus upstream of the step rather than by the presence of the step itself. The numerical experiments conducted here have been carefully documented so as to facilitate future comparisons intended to assess the relative efficiency of the present method of computation. / Doctor of Philosophy

A half-equation model of turbulence has been developed to described the eddy viscosity distribution of two and three-dimensional turbulent free shear flows. The model is derived by integrating the parabolized transport equation for the turbulence kinetic energy over the cross section of the flow. The Prandtl-Kolmogrov hypothesis is used to obtain an ordinary differential equation for the eddy viscosity. The model is used in a general purpose finite element procedure using primitive variables. The penalty function method is used, in a generalized Galerkin weak formulation of the Navier-Stokes equations, to enforce the conservation of mass. In this procedure the pressure does not explicitly appear, this significantly reducing the computation time when compared to the velocity-pressure approach. Numerical solution are obtained for four problems: a round jet issuing from a wall into still surroundings, a three-dimensional square jet issuing from a wall into still surroundings, a uniform flow past a free running propeller, and a shear flow past a free running propeller. An actuator disk with variable radial distribution of thrust and torque is used to model the propeller. The numerical solution in the far field of the round jet agrees very well with the analytical similar solution. Very good agreement between prediction and experiments is observed for the square jet problem. A simplified analysis of the flow past a propeller is used to provide the initial value of the eddy viscosity. Numerical experiments on the uniform flow past a thrusting disk confirmed the validity of the analysis and illustrated the effect of the initial value of the initial value of the eddy viscosity. For both propeller flows, agreement between predictions and experiments is excellent for both the axial and swirl velocity components at two stations located at x/D = 0.025 and 0.23. The quality of the swirl prediction is a major improvement over previous analyses. Pressure predictions are obtained for the first time, and are in reasonable agreement with the experiments. The radial velocity prediction is in fair agreement with the experiments at the station x/D = 0.025 .The discrepancy between the finite element solutions and the experiments at the station x/D = 0.23, for the pressure an the radial velocity are attributed to the presence of the body housing the propeller drive train. The body is not included in the present study. The complex three-dimensional nature of the shear flow past the propeller is very well captured in the simulation. / Doctor of Philosophy

It was generally accepted that the rate of formation of cerebrospinal °uid (CSF) is independent of intraventricular pressure [26], until A. Sahar and a host of other scientists challenged this belief. A. Sahar substantiated his belief that the rate of (CSF) formation actually depends on intraventricular pressure, see A. Sahar, 1971 [26]. In this work we show that CSF formation depends on some other factors, including the intraventricular pressure. For the purpose of this study, we used the capillary blood °ow model proposed by K.Boryczko et. al., [5] in which blood °ow in the microvessels was modeled as a two-phase °ow; the solid and the liquid volume phase. CSF is formed from the blood plasma [23] which we assume to be in the liquid volume phase. CSF is a Newtonian °uid [2, 23]. The principles and methods of e®ective area" developed by N. Sauer and R. Maritz [21] for studying the penetration of °uid into permeable walls was used to investigate the ¯ltrate momentum °ux from the intracranial capillary wall through the pia mater and epithelial layer of the choroid plexus into the subarachnoid space. We coupled the dynamic boundary equation with the Navier-Stoke's constitutive equation for incompressible °uid, representing the °uid °ow in the liquid volume phase in the capillary to arrive at our model. / Mathematical sciences / M.Sc.

Simulating the exact chaotic turbulent flow field about any geometry is a dilemma between accuracy and computational resources, which has been continuously studied for just over a hundred years. This thesis is a complete walk-through of the entire process utilized to approximate the flow ingested by a Sevik-type rotor based on solutions to the Reynolds Averaged Navier-Stokes equations (RANS). The Multiple Reference Frame fluid model is utilized by the code of ANSYS-FLUENT and results are validated by experimental wake data. Three open rotor configurations are studied including a uniform inflow and the rotor near a plate with and without a thick boundary layer. Furthermore, observations are made to determine the variation in velocity profiles of the ingested turbulent flow due to varying flow conditions. / by Felipe Ferreira Lachowski. / Thesis (M.S.C.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Modal analysis for strongly stratified lakes was extended to obtain a better understanding of the dynamics of the basin-scale motions. By viewing the basin-scale motions as a superposition of modes, that have distinct periods and three-dimensional structures, the method provides a conceptual understanding for the excitation, evolution, and damping of the basin-scale motions. Once the motion has been decomposed into modes, their evolution and energetics may be extracted from hydrodynamic simulation results and field data. The method was applied to Lake Biwa, Japan, and Lake Kinneret, Israel, and used for a theoretical study. The real lake applications showed that winds excited basin-scale motions that had a surface layer velocity structure similar to the wind stress pattern. Three-dimensional hydrodynamics simulations of Lake Biwa indicated that most of the energy input from winds was partitioned into the internal waves that decayed within a few days. The gyres, on the other hand, received much less energy but dominated the dynamics during calm periods due to their slow damping. Analyses of field data from Lake Kinneret suggested that the internal waves, excited by the strong winds every afternoon, were damped over a few days primarily due to bottom friction. Theoretical investigations of damping mechanisms of internal waves revealed that bottom friction induced a velocity anomaly at the top of the boundary layer that drained energy from the nearly inviscid interior by a combination of internal wave cancelling and spin-down. These results indicate that gyres induce long-term horizontal transport near the surface and internal waves transfer energy from winds to near-bottom mixing. Modal structure of dominant basin-scale internal waves can induce large heterogeneity of nearbottom mass transfer processes. The method presented here provides a tool to determine how basin-scale motions impact on biogeochemical processes in stratified lakes.

"CP830 Research Project and Thesis 2". Includes bibliographical references (p. 80-93) Electronic reproduction.[S.l. :s.n.],2003.Electronic data.Mode of access: World Wide Web.System requirements: Adobe Acrobat reader software for PDF files.Access restricted to institutions with a subscription.