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Orographic precipitation enhancement is the tendency of mountains to cause clouds to produce more precipitation than they would otherwise, which greatly affects the total rainfall in mountainous regions and plays a major role in flooding and mudslides. Most past studies have examined this enhancement close to the mountains themselves. The present study examined the orographic enhancement of frontal precipitation upstream of the Olympic Mountains of Washington State, using data from a Weather Research and Forecasting (WRF) regional climate simulation. Using this simulation, we strived to determine how thermodynamic and dynamic conditions affect the enhancement of frontal precipitation upstream of the Olympic Mountains. To do so, the characteristics of frontal passages were analyzed, including frontal type, orientation, velocity, warm-air moisture content, and accumulated precipitation. Of the five fronts analyzed to date, there were two cold fronts, two warm fronts, and one occluded front. We then analyzed each characteristic by comparing each event to each other and as a function of distance from the mountains. We found that all fronts slowed down as they approached the mountains, four of which to almost half of their original speeds, and some even beginning to decelerate upwards of 700 km upstream. Areas of enhanced precipitation were observed along the two cold fronts, as far upstream as 560 km. These results document upstream impacts on frontal passages, but further analysis is needed to examine additional frontal passages and determine if the observed precipitation enhancement and frontal deceleration were caused by orographic effects from the Olympic Mountains.
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THE USE OF TOPOLOGY OPTIMIZATION IN ENHANCING THE STRUCTURAL PROPERTY OF AN AUTOMOTIVE FRONT SUB-FRAME
The frontal impact is the most common in automotive collision accidents, and bending the sub-frame can directly lead to severe passenger injury and property damage. This research analyzed the crashworthiness, design, mechanical integrity, and optimization of an automotive front sub-frame structure. From the original geometry, a new sub-frame with similar mass and mounting locations is designed. Loads were applied to the front side members of the sub-frame to simulate a common frontal and partial frontal crash. A sub-frame with enhanced structural efficiency was designed using topology optimization. This improvement may preserve the lifespan of the sub-frame, reinforce the protection of passengers and the engine, and improve crashworthiness. Topology optimization is a numerical analysis technique that allows engineers to distribute materials optimally for a specific cost function. Iterative update of design variables typically relies on sensitivity information from performance analysis in each step. A simple parametric study on material candidates and design constraints was executed to evaluate various design options. Sub-frames with optimized geometries were mechanically tested against two different simplified loads mimicking frontal crashes. The dynamic behaviors were also analyzed and compared to the original design for validation.
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- Award ID(s):
- 2107140
- PAR ID:
- 10350024
- Date Published:
- Journal Name:
- Zone 1 Conference of the American Society for Engineering Education
- ISSN:
- 2332-368X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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