Background. Skeletal animation is a technique used for displaying animated movement that uses bones in a hierarchy to get a structure; these bones are transformed based on their parent bones. Vertices in a mesh are connected to one or more bones with a weight, and the vertices will move based on the bone transformation, creating an animation. Objectives. In this study, a technique called "Particle-Oriented Bounding Box Skeletal Animation", (POBBSA) is proposed. Tests were conducted with the aim of comparing traditional skeletal animation and POBBSA based on performance and quality. With the primary aim of determining if the POBBSA technique is a solution for displaying suspended sediment-based characters. Methods. The two animation approaches were implemented with the intention to conduct performance tests based on memory usage and frames per second and quality tests based on feedback from a survey. The POBBSA will differ in its way of using oriented bounding boxes and particles with a certain style of movement. Results. The POBBSA approach needs more computational power to run than traditional skeletal animation, but its memory consumption can also be lower than traditional skeletal animation. The results from the survey were mostly positive, but artifacted particles appearing on the character were also mentioned by multiple survey participants. Conclusions. Performance-wise, the POBBSA is slower than traditional skeletal animation but has a slight advantage in memory usage. When comparing POBBSA and skeletal animation in terms of quality, it appears that for the current style, POBBSA works best for cuboid characters to avoid the artifacted particles that occur in complicated models.

Measurements were made in a zero pressure gradient turbulent boundary layer over two roughness patches containing hemispherical and cubical elements. The elements were 3 mm in height and spaced 16.5 mm apart in an array containing 7 streamwise rows and 6 spanwise columns for a total of 42 elements per patch. The boundary layer thickness was approximately 60 mm, so the ratio of element height to that thickness was a large amount at k/δ = 20. A three velocity component laser Doppler velocimeter measured instantaneous velocities. Mean flow and turbulence statistics were calculated as well velocity energy spectra. Surface pressure fluctuations were measured using a two-microphone subtraction method. The results show that hemispherical elements produce larger turbulence quantities in their wakes compared to the cubes. This is due to the hemispheres having a frontal area nearly 60% larger than that of the cubes. The turbulence levels behind the hemispheres is a maximum behind the first streamwise row of elements, and decreases afterwards. The cubical elements maintain a nearly constant amount of turbulence in their wake, signifying little interaction between cubical elements. Surface pressure fluctuations vary little in the streamwise direction of the patches. The hemispherical elements produce a larger sound pressure level behind them than the cube elements do. Velocity spectra results show large normal stress energy for regions at and below the element height. The energy for locations high in the boundary layer increases as the flow moves downstream. Coherency plots show that there is a large correlation between the turbulent structure and production of shear stress at the roughness height. Any measurements taken at or below the roughness height are highly correlated under 10 kHz, while locations higher in the boundary layer are correlated under 2 kHz. / Master of Science

In urban areas, discharging wastewater into rivers is a common way to dispose of contaminants, and it is usually the most economical. Accurate information about how effluents are distributed in the receiving water body is desirable when designing industrial plants. Flow structures will be influenced by an effluent’s dilution processes during the mixing. Meanwhile, the cross-stream motions resulting from the streamline curvature can redistribute both the velocity and the shear stress, which favors the mixing behavior compared to a straight channel. However, the interactions between jet mixing behavior and the bend flow requires further investigation. In the present study, jets with different densities were discharged horizontally into a laboratory flume with a 135-degree open channel bend, and both the main and secondary flow behaviors in the bend were observed after the introduction of effluents. The acquired three- dimensional velocity data were used to validate numerical models of the effluent-bend flow. Numerical turbulence models such as the standard k-ε eddy viscosity model, non-linear k-ε model (Shih quadratic k-ε), and the k-ω SST (shear stress transport) model were employed to evaluate their accuracy. OpenFOAM was selected in the analysis for proposing better numerical models since it gives high-quality results to individualized complex fluid flows, and as an open source CFD software it can be beneficial to further develop and maintain. The first part of this study presents the implementation of the physical modelling of the proposed problems. Detailed descriptions of the experimental process were elaborated. Specifically, the three velocity components at four cross-sectional planes in the bend section were measured with and without saltwater jets by using the stereo Particle Image Velocimetry (PIV) ii technique in the laboratory flume. The experimental results show that the more pronounced effects with the jets were found at the beginning and exit of the bend. Although the jets had little effect on the maximum streamwise velocity, it was found that the occurrence of the negatively buoyant jets would affect the patterns and properties of the secondary flow in the bend. The second part of this study investigated the mechanisms underlying the two cells system, particularly when interacting with a discharged effluent jet. Detailed experimental data were used in interpreting the large center-region cell as well as small structures in the 135-degree open channel bend. A term-by-term analysis of the downstream vorticity equation was executed to investigate the various mechanisms underlying these cross-stream flow motions considering the influence of the negatively buoyant jets. The results indicated the generation and the dissipation of the streamwise vorticity with the effective terms of the vorticity equation. The third part of this study evaluated the performance of three different turbulence models with the experimental measurements. It can be concluded that fully 3D numerical models are capable of simulating the primary flow pattern in a strongly curved channel with the presence of a negatively buoyant jet. The comparison also shows that, although the outer bank cell was not predicted, the k-omega SST model can satisfactorily predict some of the smaller flow features in bend flow, such as the inner bank circulation cell and the overall form of the vorticity distributions. The results enable more reliable predictions for the characteristics and development of jets in a bend.

<p>In sheet metal forming processes, friction has decisive effects on the strain distribution in the deformed sheets and the quality of the final product due to the large surface/thickness ratio of the blank sheets. It is well known that friction in sheet forming operations is dependent on local contact conditions such as surface roughness, contact pressure and sliding velocity. Adding complexity to this frictional behavior, some rolled sheets have oriented surface roughness and show considerable frictional anisotropy. A constant friction model without consideration of these relevant phenomena is regarded as the reason why sheet metal forming simulations often fail to produce satisfying results despite the well developed material models. </p> <p>To develop a friction model which considers both of the varying conditions of local contact and the frictional anisotropy was the aim of this thesis. For this purpose, the analysis method of the friction test (draw-bend test) had to be examined for the capability to evaluate these parameters independently. Through careful study using finite element simulations, it was found that the conventional method has shortcomings in addressing pressure dependent friction due to the pressure non-uniformity existing in the test. Therefore, a new analysis method, which can evaluate pressure dependency of a friction coefficient, was developed. In the new method, contact pressure maps obtained from simulations were included in the analysis of test data.</p> <p>The new analysis method was applied to friction measurement of aluminum sheets with known anisotropic mill finish, and friction coefficients were obtained as functions of contact pressure, sliding velocity and sliding direction. In the obtained friction model, a friction coefficient is a continuous surface over the domain of contact pressure and sliding velocity. Lastly, the new friction model was implemented into a finite element code and the model was validated through circular cup drawing experiments and simulations. The comparisons showed good agreements in the aspects of punch force, cup size and failure location. Thus, the newly developed model can accurately predict the effects of anisotropic friction in sheet metal forming processes. </p> / Thesis / Doctor of Philosophy (PhD)

An experimental scale model study was conducted to investigate the onset of fluidelastic instability in a tube array subjected to axisymmetric jet flow. A tube array was constructed using aluminum tubes with 44.45 mm outer diameter, $D$, which were arranged in a square pattern with 88 mm pitch, $P$. The pitch to diameter ratio, $P/D$, was approximately 2.0. The tubes were flexibly mounted using threaded rod and tuned to a first mode natural frequency, $f_n$, of 9 Hz. Auxiliary damping devices were added to each tube, and tuned, to achieve a damping ratio, $\zeta$, of 1 % of critical. The mass damping parameter, $m(2 \pi \zeta)/(\rho D^{2})$, of the tube array was 27.9. The tube array was tested under uniform flow conditions in McMaster University's 2 ft wind tunnel to establish the critical reduced velocity, $V_{cr}/(f_n D)$, of 30.0 at the onset of fluidelastic instability. The uniform flow test established a basis for comparing the results with the existing literature and evaluating the validity of the proposed partial admission calculation. The tube array was also tested in open air using an axisymmetric jet, with two different physical arrangements, the first with the jet aimed between tubes and perpendicular to the tube spans and the second with the jet aimed at a tube face and perpendicular to the tube spans. In each case the jet flow velocity was incrementally increased to characterize the onset of fluidelastic instability. To characterize the flow dispersion through the tube array a series of velocity profile measurements were also collected. The measured velocity profiles were used to estimate the spanwise function of transverse average gap velocity, $\bar{V}(x)$, which was used to predict the equivalent critical uniform gap flow velocity, $V_{cr}$, using the concept of partial admission. The predicted $V_{cr}$ values showed reasonable agreement with the experimental results. However, the prediction method did indicate instabilities in tube rows where instability was not actually observed. A simplified prediction approach was developed which was based on using a predicted three dimensional velocity profile, $V(x,y)$, at the $z$ location of the first row tube gap, under the assumption of free field conditions, to calculate an estimate of the spanwise function of transverse average gap velocity, $\bar{V}(x)$. Although the predictions of $V_{cr}$ agreed reasonably well with the experimental results, first row instabilities were not observed in any of axisymmetric jet flow experiments. Therefore, this method can be used to estimate the the critical uniform gap velocity, $V_{cr}$, but not the spatial location of the instability. Based on the results of the experiments and calculations, adoption of the modified partial admission formula is recommended and possible avenues for further investigation and verification are suggested. / Thesis / Master of Applied Science (MASc)

<p> Forced convection mass transfer rates from single gas bubbles, with accompanying chemical reaction, were determined experimentally in the intermediate Reynolds number range. The reacting system carbon dioxide-monoethanolaminc was chosen for this study. </p> <p> A mathematical model, describing forced convection mass transfer from a single sphere with accompanying first or second order reaction, was developed and solved using finite-difference techniques. Hydrodynamic conditions in the intermediate Reynolds number region were described using Kawaguti-type velocity profiles. </p> <p> The numerical solutions of the model have been compared with the experimental results of this study as well as with previous theoretical and experimental results. </p> / Thesis / Doctor of Philosophy (PhD)

The thesis investigates pipeline plugging mechanisms that have occurred during interim stabilization transfers at Hanford. A laboratory-scale saltwell pumping test loop was designed to evaluate a surrogate of Hanford Tank 241-SX-104 supernate. The effect of surrogate flow rate, cooling water flow rate and phosphate concentrations on plugging mechanisms was investigated. Critical parameters like particle and agglomerate size, velocity and bed growth rate were determined. Theoretical models were used to compare the experimental pressure rise and temperature drop of the surrogate in the channel. An operating region in which a plug would not form was developed, based on the experimental results. Experiments are also reported on plug remediation. Unplugging experiments at varying pump pressure heads and residence time of plug in the line were performed.

General uncertainty analysis was used to evaluate the performance of a Rocket-Based Combined Cycle (RBCC) engine system. To estimate the uncertainties of test results, uncertainties of basic measurements such as temperature, pressure, mass flow rate, and thrust were determined. The desired test results of interest included specific impulse and characteristic velocity. Various possible test facilities were reviewed to obtain background information and example test run conditions. Based on the test run conditions, five methods of determining specific impulse were evaluated. Also, theoretical and actual characteristic velocities were analyzed to evaluate C* efficiency. Initially, general uncertainty analyses were completed relative to 1% accuracy for each measured variable. Then, cases were run using more realistic uncertainty estimates. The relative contributions of the different variables? uncertainties to the overall uncertainty of the selected performance parameters were also calculated. This process helps to identify the critical measurements from an uncertainty standpoint and can be a significant guide in the cost effective use of resources to reduce the test uncertainty.

An experimental study of turbulent air flow in a pipe is reported in this paper. A determination was made of the mean velocity distribution and longitudinal mean turbulent velocity distribution, both in the turbulent core and boundary layer for four different Reynolds numbers from 7300 to 58300. A traversing mechanism was designed in order to measure the turbulence correlations between two points. The variation of the macro scale length, one of the fundamental quantities in recent statistical turbulence theory across the pipe diameter was calculated for Reynolds number equal to 58300, by integrating the correlation curves. The turbulent momentum diffusivity at the center of a pipe was calculated from the correlation study and the dimension less value was found to be 0.111. Ethylene gas was injected into the center of the pipe, and in order to investigate the turbulent mass diffusivity, the concentration distribution curves of ethylene were measured at different test positions downstream from the injection point, for the same series of Reynolds numbers used in the turbulence measurement. A numerical method for calculating the diffusivity was developed. The values of diffusivity obtained. in these experiments show that the assumptions which were used by most of the authors, that of (turbulent mass diffusivity/turbulent momentum diffusivity) has a value between 1.0 to 1.6 is correct. / Thesis / Master of Engineering (ME)

No description available.