http://yetl.yabesh.ir/yetl1/handle/yetl/19056 Mon, 27 Apr 2026 11:16:59 GMT 2026-04-27T11:16:59Z http://localhost:80/yetl1/bitstream/id/184255/ http://yetl.yabesh.ir/yetl1/handle/yetl/19056 http://yetl.yabesh.ir/yetl1/handle/yetl/4311036 Numerical Prediction of Permeability and Effective Thermal Conductivity in Simple Cubic and Body-Centered Truss Structures Jeong, Ji-Ho; Heo, Jaeseung; Lee, Seungmin; Kim, Sung Jin; Han, Jae-Hung The lattice Boltzmann method (LBM) is utilized to numerically investigate the permeability and effective thermal conductivity of simple cubic and body-centered truss structures. The key objective of this paper is to analyze how different geometric parameters affect the macroscopic properties of these truss structures that are increasingly used in advanced engineering applications due to their unique thermal-fluid characteristics. Simple cubic and body-centered cubic (SC-BCC) lattice structures are modeled, and the simulations are performed to determine their permeability and effective thermal conductivity. The findings highlight that the rod diameter and simple-cubic diameter significantly influence porosity, permeability, and thermal conductivity. Larger rod diameters generally result in higher porosity and permeability but may reduce thermal conductivity. Conversely, smaller simple-cubic diameters tend to enhance thermal conductivity. These results can optimize the design and application of truss structures in heat exchangers, cooling systems, and other areas where efficient thermal management and fluid flow are critical. The study concludes that LBM is an effective tool for predicting the thermal-fluid behavior of complex porous structures, providing valuable insights for the engineering design of advanced materials. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4311036 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311035 Flow Through Scaled Additive Manufacturing Internal Passages With Correlated and Anti-Correlated Roughness on Opposing Walls Boldt, Ryan; McClain, Stephen T. Components created using additive manufacturing (AM) processes such as laser powder bed fusion (L-PBF) may exhibit a type of printing error referred to as a “layer shift error.” In this type of error, the reference location of the printing pattern shifts for each layer of material deposited. If an AM-printed component includes an internal cooling passage, the features or roughness of one wall of the passage may become anticorrelated to the roughness on the opposing wall of the passage. In this study, a rough surface from the internal passage of a L-PBF coupon was used to create two base surfaces representing flow through: (1) a passage oriented orthogonally to the printing direction and (2) a passage oriented at 45-deg to the printing direction. Each base roughness pattern was then shifted in the streamwise direction to produce either the nearest minimum correlation or the nearest maximum correlation and applied to the opposing side of the internal passage. Bulk friction factor measurements and particle-tracking velocimetry measurements of the flow were obtained for each minimum and maximum roughness correlation condition. The particle tracking results indicate that the flow shows the expected differences in flow patterns between the correlated surface conditions for the orthogonal surface. The resulting friction factors indicated statistically significant differences in the measured bulk friction between the opposing surface correlation conditions; however, the overall results suggest that correlation of roughness on opposing walls is not a significant design consideration regarding frictional losses for AM internal cooling passages. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4311035 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311031 Behaviors of a Droplet Impact on a Cylinder Chen, Xueshuo; Zhu, Jiamin; Hao, Ruizhi; Lu, Tao; Chen, Xue; Shen, Shengqiang The hydrodynamic behaviors of a droplet impacting a cylindrical surface were experimentally investigated, examining the effects of cylinder-to-droplet diameter ratio (d*), impact velocity (v0), contact angle (θ), and relative eccentric distance (e*). Temporal evolutions of droplet behavior in the circumferential and axial directions were captured using a high-speed camera. Results indicate that the spreading process can be categorized into four stages based on contact line movements: impact, spreading, oscillation, and stabilization. The rebound height after impact decreases progressively with decreasing d* and increasing Weber number (We). The maximum spreading length increases with droplet diameter and Weber number, while a lower contact angle also contributes to a greater maximum spreading length. For eccentric impacts, the effects of circumferential asymmetry and surface hydrophilicity on spreading become more pronounced with larger e*. Additionally, a novel correlation was developed to predict the maximum spreading lengths of the droplet in the circumferential and axial directions for central impacts. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4311031 2025-01-01T00:00:00Z http://yetl.yabesh.ir/yetl1/handle/yetl/4311027 Flow-Induced Vibration Analysis of Rigid Horizontal Pipelines Under Two-Phase Flow and Leak Conditions Dang, Zhuoran; Chen, Haobin; Hugo, Ron; Park, Simon This study investigates the vibrational response of horizontal rigid pipelines subjected to internal two-phase flow with simulated leaks. Using spectral-based contour plots and vibrational energy measurements, we analyze the dynamics across various flow velocities and patterns in a 5-m-long, 2-in diameter pipeline. Results indicate that flow patterns and Reynolds numbers significantly influence vibration characteristics. Except for bubbly flow, increasing the mixture Reynolds number amplifies power spectral magnitudes and extends excitation to higher frequencies, independent of leaks. Fluid loss enhances spectral magnitudes at higher liquid Reynolds numbers, with gas Reynolds numbers further intensifying vibration. Leaks modify spectral spikes due to multiphase flow fluctuations, making them more pronounced and persistent. Vibrational augmentation is predominant in the direction of fluid loss, peaking at the leak location and attenuating with increasing distance from the leak location. Slug flow demonstrates the highest increase in vibrational energy. Bubbly flow exhibits maximum leak to no-leak amplification (15–25 dB), followed by slug flow (5–15 dB), and plug flow (<10 dB). Minimal leak-induced effects (<5 dB) occur in stratified wavy and low-velocity intermittent flows. This study establishes a foundation for leak detection and pipeline health monitoring, emphasizing the role of flow-induced vibration analysis in enhancing pipeline safety. Wed, 01 Jan 2025 00:00:00 GMT http://yetl.yabesh.ir/yetl1/handle/yetl/4311027 2025-01-01T00:00:00Z