Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session X13: CFD: Applications I |
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Chair: Randall McDermott, National Institute of Standards and Technology (NIST) Room: 155 C |
Tuesday, November 26, 2024 8:00AM - 8:13AM |
X13.00001: Two-Dimensional Modeling and Simulation of Nonlinear Isothermal Gradient Elution Chromatography with Radial Concentration Gradients Muhammad Abid Chromatography is a widely used separation technique, often relying on conventional unidimensional isocratic models. However, these models fail to capture radial concentration gradients from imperfect sample injection and the benefits of gradient elution, where solvent strength varies. This study proposes a two-dimensional nonlinear isothermal equilibrium dispersive model |
Tuesday, November 26, 2024 8:13AM - 8:26AM |
X13.00002: Abstract Withdrawn
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Tuesday, November 26, 2024 8:26AM - 8:39AM |
X13.00003: Assessing relevant roughness scales for accurate predictions of iced airfoils in both glaze and rime conditions Tommaso Bellosta, Alessandro Donizetti, Federico Zabaleta, Brett Bornhoft, Suhas Jain, Sanjeeb T Bose, Alberto Guardone Accurately predicting aircraft performance degradation due to icing is crucial for certifying next-generation aircraft designs. Current ice accretion models often simulate ice growth as two-dimensional and lacking small scale distributed roughness observed in ice accretion experiments. To evaluate the impact of local roughness on aerodynamic loads of iced airfoils, we conducted RANS and wall modeled LES analyses on a hierarchy of filtered ice shapes under rime and glaze conditions. Baseline shapes of realistic ice were derived from laser scans of ice formed on a NACA23012 airfoil at the NASA Glenn IRT. We generated increasingly smoothed ice shapes using a volume-preserving Laplacian smoothing algorithm to the limit of two-dimensional shapes like those generated from ice accretion models. For glaze ice with horn-like structures, filtered roughness scales minimally affect lift, drag, and pressure profiles. However, for rime ice conditions, removing the smallest roughness scales significantly alters the lift curve to the extent of mispredicting the stall condition. This highlights the need for either artificially generated roughness in rime-iced environments or improved sub-grid roughness models. |
Tuesday, November 26, 2024 8:39AM - 8:52AM |
X13.00004: Efficient Inflow Generation for Wind Loading Predictions for Low-Rise Buildings Mattia Fabrizio Ciarlatani, Catherine Gorle Wind loading predictions for low-rise buildings require an accurate representation of the roughness sublayer within the incoming atmospheric boundary layer. However, to correctly predict the roughness sublayer, a substantial computational cost is required, as the terrain roughness needs to be resolved. In this study, we explore a framework that combines synthetic turbulence generation at the inflow and volume forcing within the roughness sublayer to represent the effect of the roughness elements in a computationally efficient manner and reproduce a wide range of target boundary layers. To establish the framework we first build a database of LES simulations for a range of roughness configurations representative of setups that can be obtained with the Terraformer at the University of Florida Boundary Layer Wind Tunnel. The simulations resolve the terrain roughness through an immersed boundary method and serve as the foundation for developing a model that correlates terrain roughness with boundary layer characteristics, thus allowing us to identify a suitable roughness configuration for generating specific target boundary layer conditions. Next, we integrate synthetic turbulence generation and computationally efficient volume forcing techniques to reduce the number of roughness elements that have to be represented with the immersed boundary method while still reproducing the target boundary layer flow. |
Tuesday, November 26, 2024 8:52AM - 9:05AM |
X13.00005: Topology optimization of manifold fluid channel design with mass flowrate control Kewei Gao, Hyun Wook Kang, Min Liang Wang, Hernando Leon-Rodriguez, Congyu Mao Topology optimization for flow problems has garnered considerable interest recently across various applications, including enhancing the efficiency of energy systems through optimized energy, momentum, and heat transfer. Conventional design methods typically rely on parametric models, which may limit the discovery of novel conceptual designs and their interconnections. In contrast, topology optimization offers a pathway to generate novel configurations of these components, aiming to enhance their efficiencies and ensure target flow distribution—an essential factor in optimizing the performance of energy system components. In this study, a topology optimization framework is proposed to address the multi-outlet problem with mass flowrate control. The objective function is normalized power dissipation, which can also be considered as pressure drop. The control includes both volume control and mass flowrate control. The mass flowrate control for each outlet is defined with lower and upper limits, set at 1% below and above the target mass flowrate, respectively. For cases with Reynolds numbers of 100, 300, and 500, the mass flowrate control across six outlets achieves an average control accuracy of 99.02%, which is within a reasonable range for the control target. The proposed method shows potential for application in heat exchanger systems to improve energy efficiency. |
Tuesday, November 26, 2024 9:05AM - 9:18AM |
X13.00006: Numerical study of the flow and thermal characteristics in an internal permanent magnet synchronous motor Jaebeom Kwon, Gihun Son Recently, internal permanent magnet synchronous motors (IPMSMs), which feature high energy density due to the incorporation of permanent magnets within the rotor, have emerged as an alternative to traditional induction motors in industrial applications. The IPMSM, consisting of a stator, a rotor with imbedded magnets, a shaft, bearings, a fan and enclosure, converts electrical energy into mechanical energy through the interaction between the magnetic fields around the stator and rotor core induced by the electric windings. The motor efficiency is determined by several losses related to electrical resistance, magnetic field change and mechanical friction. The losses act as a thermal source that increases the motor temperature, reducing its efficiency. Therefore, understanding the thermal characteristics of IPMSM is essentially important for enhancing their efficiency and ensuring stable operation. In this work, three-dimensional computations are performed to investigate the flow and thermal characteristics of IPMSM. The computations show a comprehensive temperature distribution in the motor, closely linked to both the internal and external flow characteristics of the motor. The effects of the driving conditions, such as rotational speed and load torque, on the motor's temperature distribution are investigated. |
Tuesday, November 26, 2024 9:18AM - 9:31AM |
X13.00007: Lattice Boltzmann method-based large eddy simulation of turbulent flow over different canopy arrays Yuqian Li, Jie Shen, Lian-Ping Wang Understanding turbulent flows over street canopy is important for predicting the environmental flow dynamics and designing smart cities, but the modeling of such flows is still challenging as more structures of different scales are involved. Three-dimensional time-dependent flow statistics are required for in-depth understanding of these complex flows. Large eddy simulation (LES) is an efficient method for simulating large-scale flow structures but its accuracy remains to be examined. The lattice Boltzmann method-based large eddy simulation (LBM-LES) has gained increasing attention in the engineering fields over the past decades. In this work, the multi-relaxation time (MRT) LBM-LES incorporating Wall-Adapting Local Eddy-Viscosity (WALE) is developed to simulate flow over canopies. Firstly, the code is validated using the flow over a single building with aspect ratio 1:1:2, and a good agreement is found between LBM-LES and the results from the literature. Then, turbulent flows over canopies with different heights and distributions are simulated and results are compared with experimental data. The simulated flows then allow us to explore the differences between mixing-layer analogy and roughness sublayer for this flow configuration. |
Tuesday, November 26, 2024 9:31AM - 9:44AM |
X13.00008: Sphagnum Moss Vortex Rings: Cap or No Cap? Larry Liu, Dwight L Whitaker On warm summer days the capsules Sphagnum moss dehydrate and shrink, causing the gas contained within to increase in pressure. The strains within the collapsing capsule and the pressure of the gas within cause force the lid of the capsule to break free releasing the gas and spores within. The escaping gas forms a vortex ring, which carries the dust-like spores to a height of over 10 cm where they can be dispersed by wind. This dispersal mechanism, which is not observed in any other bryophytes, might explain how Sphagnum has become so prolific in its short 20 Ma history. |
Tuesday, November 26, 2024 9:44AM - 9:57AM |
X13.00009: ABSTRACT WITHDRAWN
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