The MSU TURBO code, distributed to U.S. engine companies by NASA Glenn, is a heavily used parallel compressible Reynolds-averaged Navier-Stokes flow solver for multistage turbomachinery flows, primarily for compressible flows at subsonic and transonic speeds. Many low speed turbomachinery flows in aerial vehicles or marine propulsion systems can not be effectively addressed by compressible flow solvers. It is well known that compressible flow equations face difficulties at low Mach number due to the large disparity of the acoustic and convective wave speeds. The current study is to develop and implement the computational capability for flow simulations at low Mach number, or incompressible Mach regime, under the framework of the MSU TURBO code. This is accomplished by applying a global preconditioning scheme to the unsteady term of the compressible governing equations and solving the conservative Riemann flux based on primitive variables. The preconditioning scheme is a single parameter diagonal matrix depending on a reference Mach number which represents the global flow properties in the flow simulation. For flows in rotating machines where speed varies along the radial direction from the axis of the rotation, it is found that a modified preconditioning parameter is necessary to assure numerical stability in simulating low Mach number rotating flows. The effectiveness of the modified preconditioning scheme has been analyzed, under various flow conditions, through Fourier footprints and validated by numerical investigations. The development of a preconditioned structured turbomachinery flow solver was accomplished in this dissertation. The conservative form of the governing equations were cast in the non-inertial relative rotating frame in terms of primitive variables and absolute velocity vectors. Characteristic-based boundary conditions, with implicit treatment of the source term resulting from the rotating relative frame, are derived for internal and external flows. The implicit finite volume scheme is developed for the preconditioned scheme with the flux Jacobians evaluated by either a flux approximate method or flux-vector-splitting. The viscous flux is also treated implicitly, and an analytic form of viscous flux Jacobians was developed in the preconditioned flow solver to reduce numerical uncertainties, and computing time. A series of flow simulations have been carried out by this preconditioned unsteady turbomachinery flow solver. The simulations of viscous boundary layer development over flat plates at very low Mach numbers demonstrate the effectiveness of the preconditioning algorithm. Computations of compressor rotor, and rotor/stator at subsonic, and transonic flow regions with acceptable results indicate that the preconditioned TURBO solver is compatible with the compressible version of the TURBO solver for subsonic and transonic flows. Moderate improvement in numerical convergence for flows in a rotating frame with mixed flow speeds is observed in the case of a tiltrotor blade at hover. The marine propeller simulation demonstrates the accomplishment of the preconditioned TURBO solver for an incompressible flow simulation. In the simulation of a low speed centrifugal compressor, the preconditioned TURBO is able to predicate the wake locations accurately.

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Dementia, a stepwise deterioration of cognitive function, affects over 700,000 people in the UK, resulting in over 60,000 deaths and a cost of over £1.7 billion each year. It is believed to have a combination of vascular and degenerative origins and to have correlations with localised lesions, or infarctions, in the brains of affected patients. Mini-strokes are one of the causes for this disease as the presence of ischemia is highly related to the risk factors for dysfunction of the neurovascular unit. The underlying interacting mechanisms are, however, often very complex and they remain largely poorly understood. The cerebral microvascular bed is highly irregular and localised variations in its structure are large. To capture these variations, statistical algorithms are required, rather than large volumes of expensive experimental data. Therefore, accurate modelling of blood flow and oxygen transport at the microvascular level is important in improving our understanding of the structure and function of the cerebral vasculature and hence of brain diseases. A novel algorithm is proposed here to create artificial microvascular networks that match quantitatively experimental data previously obtained in human brain tissue. Blood flow and oxygen transport in the network and the tissue are analysed through both discretised and continuum transport models. By disabling flow sources, ischemic events can be simulated. Using multiple networks, the influence of individual network structures on the response to ischemia is analysed. The relationship between the discretised and continuum formulations of the model is quantified, providing a means for scaling up the model over multi length scales. Finally, the phenomenon of microvessel collapse under ischemic conditions is examined and it is shown that this is fundamentally dependent upon the variability found at the network level, since it cannot be modelled by a continuum model. An initial infarction is also found to facilitate the occurrence of collapse events for most networks.

Low pressure chemical vapor deposition (LPCVD) is one of the important technics in the semiconductor process recently. The computer simulation is the best efficient method on the process research. This research use numerical method to study the performance of showerhead parameters, and to confer the flow field distribution and deposition rate under different design parameters in LPCVD of silicon (Si). In this simulation, the CVD reactor modelings are constructed and discredited by using implicit finite volume method. The grids are arranged in a staggered manner for the discretization of the governing equations. Then the SIMPLE-type algorithm is used to solve all of the discretized algebra equations. The variable parameters are: (1) the inlet velocity, (2) the holes diameter of showerhead, (3) the showerhead size. The results show that using the showerhead can adjust the flow filed distribution and it is better for film thickness uniformity. The holes diameter and distribution density have relations with film uniformity. We also proved that the growth rate increase with the inlet velocity under the some conditions.

This work describes a new taxonomy for elastic, sedimentary porous media. The taxonomy is synthesized for the investigation and characterization of ground-water flow from accumulating developments in the genetic analysis of elastic, sedimentary depositional structures. Genetic analysis recognizes spatial associations of elastic, sedimentary structures imposed during genesis. The taxonomy is a nested hierarchy of discrete elastic, sedimentary structures distinguished by the bounding surfaces created during their emplacement and rearrangement. The investigation and characterization of a specific ground-water flow system in elastic, sedimentary porous media can be improved by imposing a structural context on lithologie observations, geophysical measurements, head measurements, and hydraulic conductivity estimates. Globally-valid and transferable descriptions of structures in the taxonomy from modern exposures, outcrops, and densely sampled subsurface systems are modified to fit site-specific geologic observations and measurements. A specific procedure is developed for applying the taxonomy in the investigation and analysis of ground-water flow. The procedure quantitatively measures the hydraulic validity of alternative geologic interpretations of site-specific data under the taxonomy. The application of the taxonomy and procedure to a typical set of data types, densities, and quality is illustrated with data from a site of ground-water contamination investigation.

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The main text of the thesis consists of seven chapters. Following the literature survey, the work in Chapter 2 focuses on the study of the whole process of pressure die casting. The necessity of reclassification against the traditional 'three-stage' description is introduced in order to build a new basic tenet in constructing theoretical and practical investigations, which leads to the creation of fluid dynamic mathematical models of the process. On the basis of Chapter 2, Chapter 3 concentrates on dealing with the computer simulation of filling flow patterns occurring in the third stage that play the most important role in the process. The Simplified Marker And Cell (SMAC) method is used to obtain the computational results of the filling patterns of pressure die casting processes. On the basis of the computational analysis of typical examples, the viscosity, gravitational force and velocity effects on the overall filling pattern are examined, that lead to a validation of the important hypothesis that an ideal liquid can be used in numerical simulation of filling patterns and this enables one to achieve a more effective computer program for a complex cavity by quasi-3D or 3D models. Chapter 4 treats a specific problem of the residual flow that exists in the final (fifth) stage of the process. Mathematical models of residual flow are derived. Chapter 5 mainly consists of two parts. The first part deals with the application of similitude laws for simulating flows in pressure die casting processes. Detailed analyses and criteria on different relationships between model and prototype are given in order to correct previously offered formulae by Eckert (1989). The results of numerical simulation presented in Chapter 3 are also extended to validate the similitude criteria. The second part of Chapter 5 presents the use of a charge coupled device(CCD) for studying the diversity of fluid motion including the filling pattern, residual flow, thermals and air entrapment during cavity-fill and post cavity-fill within a one single shot cavity filling in water analogue experiments. A discussion, conclusions and suggestions for further study of the subject concerned are presented in Chapters 6 and Chapter 7.

The paper primarily outlines fundamental issues of electron microscopy. The paper follows with analysing pumping of gas into EREM sample chambers at various pressure levels by using SolidWorks Flow Simulation in SolidWorks system. The results of analyses are assessed with respect to requirements so that the pressure in the track of primarily electrons is as low as possible with the view to reduce probability of its scattering.

No description available.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 35). / Traffic simulation is an important aspect of understanding how people move throughout various road systems. It can provide insight into the design of city streets and how well they can handle certain traffic patterns. There are various simulators available, ranging from free tools such as TRANSIMS to commercial implementations such as TransCAD. The available tools provide complex, large scale and very detailed simulation capabilities. The Virtual City Testbed addresses aspects that are not available in these tools. Primarily, the test bed provides the ability for interaction with the traffic system in real time. Instead of basing the simulation solely on automated vehicle models, we allow for human participants to interact with individual cars via a remote simulation client. Thus we are able to inject realistic human input into our simulation. A second feature provided by our simulation is the ability to disrupt a simulation in progress. A disruption usually involves disabling access to a set of streets which forces the traffic to adapt as it moves around the road system. This yields a way to study the way traffic motion changes within a road system under the presence of unexpected events such as natural disasters or other real life disruptions. Ultimately, we provide a test bed for studying traffic under varying environmental conditions. / by Oleg I. Kozhushnyan. / M.Eng.