Session D: 3:30PM – 5PM
Engineering. Session D – Oral Presentations. Sorenson, (2nd floor), Alumni House
SESSION D (3:30-5:00PM)
Location: Sorenson (2nd floor), Alumni House
Evaluating and Comparing the Effects of Domain Resolution in WRF
Hans Klomp, Brigham Young University
Faculty Mentor Bradley Adams, Brigham Young University
SESSION D 3:30-3:45PM
Sorenson, (2nd floor), Alumni House
Engineering
With the greater Salt Lake area (GSLA) growing rapidly every year, it is important to understand how metropolitan growth can affect local meteorology. The physical layout and anthropogenic heating in urban environments can cause an increase in temperature up to 7º C relative to a comparable rural area, which often leads to higher levels of PM2.5 and ozone. The Weather Research and Forecasting Model (WRF) can predict meteorological behavior of the GSLA. The use of modeling techniques like an Urban Canopy Model (UCM), and Local Climate Zones (LCZ) can improve the representation of urban characteristics. These tools give specific classifications to different parts of the GSLA and allow us to compute data regarding temperature, wind speed, humidity, and an array of other variables. A more accurate representation of the urban environment allows for better simulation results. To assess the impacts of future growth scenarios, a baseline model of current urban properties and meteorological conditions must be established. Part of this process is to assess model sensitivities to discretization parameters. In this case computational domain resolution. Resolution is determined by how many grid cells of uniform size can reside within the domain. More grid cells with smaller areas within the domain give a higher resolution and more precise results but take longer to calculate. Fewer grid cells per domain result in lower resolution which saves time and allows for more simulations, but at the cost of precision. This presentation discusses how grid resolution was changed and the resulting differences in predicted meteorological properties. Results showed that predicted temperatures varied based on grid size for a downtown location.
Micro-DIC as a method to measure through-thickness strain in CBT specimens
Addison McClure, Brigham Young University
Faculty Mentor David Fullwood, Brigham Young University
SESSION D 3:50-4:05PM
Sorenson, (2nd floor), Alumni House
Engineering
Continuous bending under tension (CBT) is a sheet metal forming process during which a material is repeatedly passed through a series of rollers. CBT has been observed to significantly increase a material’s elongation to failure (ETF), meaning the material will stretch further before breaking. This process ultimately improves the formability of sheet metal at room temperature, making metals stronger and lighter without the need for more expensive heating processes. Digital image correlation (DIC) is a non-contact optical method used to measure the deformation of a material subjected to a load. This research aims to determine if DIC can be used to measure through-thickness strain in CBT specimens at the microscale. Micro-DIC was used to measure strain in titanium samples. To do this, a DIC pattern was applied to the edge of each sample using a microstamp. Pictures were taken of the stamped region throughout the CBT process using a variety of imaging methods, including cameras and optical microscopes. The strain in the sample was then calculated by tracking the displacement of the pattern across images. From initial testing, we can conclude that microstamping for through-thickness DIC can be used to successfully measure the strain of CBT specimens at the microscale. This new methodology can be used in a wide variety of applications. In CBT experiments, micro-DIC allows us to study local deformation, which is critical in determining how CBT increases a material’s ETF. More generally, micro-DIC is a relatively accessible method that can obtain extremely detailed strain data.
Surrogate Fold Hinges: Replacing Paper Folds in Origami
Phebe Ramsdell, Brigham Young University
Faculty Mentor Spencer Magleby, Brigham Young University
SESSION D 4:10-4:25PM
Sorenson, (2nd floor), Alumni House
Engineering
Origami has been practiced for generations, but only recently have we seen relevant usage of this art form emerge in technological applications. These applications have been found in space arrays for a compact design during space travel, uses in the biomedical world for surgical technology, and can even be utilized in safety products such as a Kevlar ballistic barrier, an easy set up bullet proof shield for police officers. With applications, comes the need for designers and manufacturers to consider specific hinges used for unique origami-based mechanisms. A traditional hinge will come with complications as enhanced complex mechanisms come into play. Therefore, compliant hinges are most advantageous concerning problems such as thickness accommodation and fabrication. Differing materials create difficulty because it may add flexibility or stiffness in the mechanism which will affect how the surrogate folds bend. With the help of current technology, we have researched existing surrogate fold joints that could be used as compliant hinges. Using this research, we are creating a surrogate fold characterization database. This tool will give designers the chance to consider the properties of their origami-based mechanism during the design stage, then use the database to select hinges that will fit their specific criteria. This surrogate fold characterization database will cut out time spent testing folding motion with a prototype. It will grant the engineer an efficient tool of determination, in which they can choose a compliant hinge that optimizes the function of their origami-based mechanism.
Refining a WRF-Based Urban Canopy Model for the Greater Salt Lake Area
Natalie White, Brigham Young University
Faculty Mentor Bradley Adams, Brigham Young University
SESSION D 4:30-4:45PM
Sorenson, (2nd floor), Alumni House
Engineering
The greater Salt Lake area (GSLA) has experienced significant urban growth in recent years, which is expected to continue. This urbanization is contributing to the development of an urban canopy. An urban canopy describes the effects of urban land cover characteristics on meteorological conditions, including temperature, humidity, and wind speeds. Urban canopies are associated with increased temperatures and greater concentrations of pollutants such as ozone. The Weather Research and Forecasting (WRF) model, when used with an urban canopy model (UCM), can provide valuable information on the effects of future urban growth scenarios.The research conducted focused on two aspects of model development, including the implementation of local climate zones (LCZs) and the selection of a land surface model (LSM). Local climate zones allow for a greater number of land cover categories, more precise mapping of said categories, and the customization of urban parameters for each category. LCZs affect WRF outputs such as temperature, humidity, and wind speeds. Their proper use has been shown to increase the accuracy of the model and has potential to create more accurate predictions for future urban growth scenarios. Land surface models control the representation of different physical processes, such as surface flux. The Noah Scheme (the unified NCEP/NCAR/AFWA scheme) was compared with a 5-layer thermal diffusion scheme and the more advanced Noah multi-physics scheme. The effects of these different methodologies on WRF outputs, including temperature, were evaluated to determine which LSM can most accurately represent the GSLA in the WRF-based UCM model. Development of an accurate WRF-based Urban Canopy model for the GSLA will provide more reliable information on the effects of future urban growth scenarios for the Greater Salt Lake Area specifically. Findings from this research and the resultant model can be used for the same purposes in other locations.
