Development of a moment method to solve the three-dimensional boundary layer equations

Moment method for solving nonsimilar laminar boundary layer equations for three dimensional cross flo

On the calculation of three dimensional laminar boundary layer flows

An approximation which reduces the computation of three dimensional, laminar, compressible, boundary layer equations to the problem of solving two dimensional type boundary layer equations is presented. A comparison of this method with a fully three dimensional boundary layer calculation is provided

Finite difference solution to the three-dimensional, incompressible thermal energy boundary-layer equation

An implicit numerical method has been adopted for the solution to the three-dimensional, energy boundary-layer equation. The energy equation is written in terms of a dimensionless temperature function, the relative stagnation-enthalpy difference, and transformed by the introduction of a Blasius-type transformation of coordinates as well as dimensionless stream functions. The method is applied to the problem consisting of an infinite cylinder joined with its axis perpendicular to a thin, flat, heated plate. A Prandtl number equal to one is simply considered

Punching – the reasons of failure in complex trinity

Príspevok je venovaný objasneniu príčin zrútenia nosnej konštrukcie garáži v polyfunkčnom komplexe Trinity, ktoré nastalo v júli roku 2012 v Bratislave. Lokálne zlyhanie strešnej dosky malo za následok úplnú deštrukciu päť poschodovej budovy, ktorej stropné konštrukcie boli navrhnuté ako lokálne podopreté dosky.Paper deals with clarifying of the reasons of car garage structural collapse in multifunctional complex Trinity in Bratislava which occurred in Bratislava in July 2012. Local failure of roof slab caused total destruction of five storey building, where floors were designed as RC flat slabs

A fast, low-memory, and stable algorithm for implementing multicomponent transport in direct numerical simulations

Implementing multicomponent diffusion models in reacting-flow simulations is computationally expensive due to the challenges involved in calculating diffusion coefficients. Instead, mixture-averaged diffusion treatments are typically used to avoid these costs. However, to our knowledge, the accuracy and appropriateness of the mixture-averaged diffusion models has not been verified for three-dimensional turbulent premixed flames. In this study we propose a fast,efficient, low-memory algorithm and use that to evaluate the role of multicomponent mass diffusion in reacting-flow simulations. Direct numerical simulation of these flames is performed by implementing the Stefan-Maxwell equations in NGA. A semi-implicit algorithm decreases the computational expense of inverting the full multicomponent ordinary diffusion array while maintaining accuracy and fidelity. We first verify the method by performing one-dimensional simulations of premixed hydrogen flames and compare with matching cases in Cantera. We demonstrate the algorithm to be stable, and its performance scales approximately with the number of species squared. Then, as an initial study of multicomponent diffusion, we simulate premixed, three-dimensional turbulent hydrogen flames, neglecting secondary Soret and Dufour effects. Simulation conditions are carefully selected to match previously published results and ensure valid comparison. Our results show that using the mixture-averaged diffusion assumption leads to a 15% under-prediction of the normalized turbulent flame speed for a premixed hydrogen-air flame. This difference in the turbulent flame speed motivates further study into using the mixture-averaged diffusion assumption for DNS of moderate-to-high Karlovitz number flames.Comment: 36 pages, 14 figure

The M-Machine Multicomputer

The M-Machine is an experimental multicomputer being developed to test architectural concepts motivated by the constraints of modern semiconductor technology and the demands of programming systems. The M- Machine computing nodes are connected with a 3-D mesh network; each node is a multithreaded processor incorporating 12 function units, on-chip cache, and local memory. The multiple function units are used to exploit both instruction-level and thread-level parallelism. A user accessible message passing system yields fast communication and synchronization between nodes. Rapid access to remote memory is provided transparently to the user with a combination of hardware and software mechanisms. This paper presents the architecture of the M-Machine and describes how its mechanisms maximize both single thread performance and overall system throughput

Developing Tornado Climatology in the Southern Great Plains per Phases of Prominent Oceanic Oscillations

Meteorologists are continually working toward a greater understanding of which atmospheric environments are most conducive for tornado development. This Capstone project analyzed tornado occurrences across Texas, Oklahoma, Arkansas and Louisiana during the period 1950 through 2009 to determine if any correlation exists between the location and frequency of tornado activity and the phases of the El Nino-Southern Oscillation, the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation. While it was determined that no phase of any of the oscillations studied was significantly more dominant over the other(s) concerning frequency, this project does identify some spatial shifts in tornado activity depending on the phase. By establishing basic tornado climatology, this project also provides the basis for continued research in a number of related topic

Quantifying lawn irrigation contributions to semi-arid, urban stream baseflow with water-stable isotopes

2020 Spring.Includes bibliographical references.In semi-arid cities, urbanization can lead to elevated baseflow during summer months. One potential source for the additional water is lawn irrigation. We sought to quantify the presence of lawn irrigation in Denver's summertime baseflow using water-stable isotope (δ18O and δ2H) analysis of surface water, tap water, and precipitation. If lawn irrigation contributed significantly to baseflow, we predicted the isotopic composition of Denver's urban streams would more closely resemble the local tap water than precipitation or streamflow from nearby grassland watersheds. We expected the tap water to be distinctive due to local water providers importing much of their source water from high elevations. Thirteen urban streams and two grassland streams were selected for sampling. The thirteen urban watersheds ranged from 3.9 km2 - 63.3 km2 in drainage area and 22% - 44% in imperviousness. The two grassland watersheds had drainage areas of 3.7 km2 and 7.5 km2 as well as 1% and 5% imperviousness. None of the streams had high-elevation headwaters or wastewater effluent, and the grassland streams did not receive irrigation. Tap water was sampled from five local water provider service areas. Wide spatial and temporal variation in isotopic composition was observed within the stream, tap and precipitation samples. Comparison of samples between nearby watersheds revealed that proximity did not imply similar isotopic values. Streamflow analysis focusing on summer 2019 revealed that the grassland watersheds flowed for 60% of the summer while urban watersheds flowed for 90% - 100% of the summer. A two end-member isotope mixing model using tap and precipitation end-members estimated that tap water contributed 61% - 97% of urban streamflow on specific days in late summer. After taking estimated contributions from infrastructure leakage into account, we conservatively determined the lawn irrigation return flows made up 4% - 75% of the modeled baseflow. Quantifying the contribution of lawn irrigation to urban baseflow will provide a basis for understanding how changes to lawn irrigation efficiency would affect water yield in the Denver metropolitan area