The article cites a research conducted by Wright-Patterson Air force Research Laboratory on the complexity of fluid dynamics. The purpose of the research was to explore passive- and active-control strategies. Experime...
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The article cites a research conducted by Wright-Patterson Air force Research Laboratory on the complexity of fluid dynamics. The purpose of the research was to explore passive- and active-control strategies. Experiments and hybrid calculations were performed by the U.S. National Aeronautics and Space Administration Langley in order to understand the noise-generation mechanisms associated with large-scale unsteady structures near the leading-edge slat of a multi-element high-lift configuration.
Reports developments on fluid dynamics as of December 2002. Details on the three categories of fluid dynamics; Use of detached-eddy simulation technique in resolving aircraft turbulence; Formulation of the incompressi...
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Reports developments on fluid dynamics as of December 2002. Details on the three categories of fluid dynamics; Use of detached-eddy simulation technique in resolving aircraft turbulence; Formulation of the incompressible Navier-Stokes equations; Measurement of pressure fluctuations.
Discusses the developments on the aerospace applications of fluid dynamics in 2001. Development of a concept for a long-run-time, hypersonic test facility that will duplicate extreme temperature and chemistry flight c...
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Discusses the developments on the aerospace applications of fluid dynamics in 2001. Development of a concept for a long-run-time, hypersonic test facility that will duplicate extreme temperature and chemistry flight conditions; Development of a methodology to provide an assessment of error in computational fluid dynamics calculations; Design and test of an ultracompact, subsonic engine inlet duct based on the technology of active inlet flow.
Discusses developments in the area of fluid dynamics in the United States aerospace industry for 2003. Spectral-volume method developed by researchers at Michigan State University and National Aeronautics and Space Ad...
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Discusses developments in the area of fluid dynamics in the United States aerospace industry for 2003. Spectral-volume method developed by researchers at Michigan State University and National Aeronautics and Space Administration-Ames; In-flight full-scale demonstration of active flow control in DARPA's Micro Adaptive Flow Control program; Experimental and theoretical fluid dynamics.
[Auto Generated] CHAPTER PAGE 1 Development of the Laboratory 1 2 Laboratory Facilities 7 3 Effect of Projectile Components bn the Flow Diagram 69 4 Cavitation and Entrance Bubbles 96 5 Nose Cavitation Ogives and Sphe...
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[Auto Generated] CHAPTER PAGE 1 Development of the Laboratory 1 2 Laboratory Facilities 7 3 Effect of Projectile Components bn the Flow Diagram 69 4 Cavitation and Entrance Bubbles 96 5 Nose Cavitation Ogives and Spherogives . . 118 6 Hydrodynamic Forces Resulting from Cavitation on Underwater Bodies 134 7 Cavitation Noise from Underwater Projectiles . 155 8 Forces on Finless Body Shapes 171 9 Stabilizing Surfaces on Nonrotating Projectiles . 175 10 Effects of Projectile Components on Drag, Cros
Sand management in wellbores is a significant challenge in the industry, notably impacting equipment integrity and operational safety- particularly in offshore oil and gas operations affected by the onset of sand prod...
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Sand management in wellbores is a significant challenge in the industry, notably impacting equipment integrity and operational safety- particularly in offshore oil and gas operations affected by the onset of sand production along with hydrocarbons. Recent advancements in fiber- optic sensing, especially through distributed acoustic sensing (DAS) experimental data, have enabled the continuous monitoring of sand ingress and migration. In this study, we use computational fluid dynamics (CFD) to accurately model sand transport by validating the simulations against the DAS data in a 40- ft- long, 2- in.-diameter experimental flow loop. The validation and verification (V&V) process demonstrates the CFD model's accuracy in both steady- state and transient conditions, through predictions of key flow parameters such as sand slip velocity, sand concentration profiles, and sand arrival times against published experimental data, as well as verification of CFD methodology against similar simulation studies. Next, we used the CFD model to simulate the fiber- optic experimental DAS data for sand slurry transport in a pipe through an injection port with conditions of carrier fluid velocity = 0.93 m/s and dispersed phase (sand) particle diameter of 300 mu m at a concentration of 0.001 v/v. To address uncertainties during sand production, a parametric study under transient conditions was conducted with varying boundary conditions in the CFD model. It examined fluid flow velocities at both 0.53 m/s and 0.93 m/s, below and above the critical settling velocity of the sand respectively, and the effects of varying sand particle diameters (125 mu m and 600 mu m). Our research represents a significant advancement in sand management strategies, offering a robust and cost- effective tool for simulating real- world scenarios to improve operational efficiency. By providing detailed insights into flow dynamics and enabling robust predictions across various conditions, this study contributes subs
This paper describes the numerical implementation in a high-performance computing environment of an open source library for model order reduction in fluid dynamics. This library, called pyLOM, contains the algorithms ...
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This paper describes the numerical implementation in a high-performance computing environment of an open source library for model order reduction in fluid dynamics. This library, called pyLOM, contains the algorithms of proper orthogonal decomposition (POD), dynamic mode decomposition (DMD) and spectral proper orthogonal decomposition (SPOD), as well as, efficient SVD and matrix-matrix multiplication, all of them tailored for supercomputers. The library is profiled in detail under the MareNostrum IV supercomputer. The bottleneck found to be in the QR factorization, which has been solved by an efficient binary tree communications pattern. Strong and weak scalability benchmarks reveal that the serial part (i.e., the part of the code that cannot be parallelized) of these algorithms is under 10% for the strong scaling and under 0.7% for the weak scaling. Using pyLOM, a POD of a dataset containing 1.14 x 108 gridpoints and 1808 snapshots that takes 6.3Tb of memory can be computed in 81.08 seconds using 10368 CPUs. Additionally, the algorithms are validated using the datasets of a flow around a circular cylinder at Re-D = 100 and Re-D = 1 x 10(4), as well as the flow in the Stanford diffuser at Re-h = 1 x 10(4).
The quasi-continuous-wave laser directed energy deposition (QCW-DED), a form of directed energy deposition (DED), has garnered growing interest in recent years due to its ability to reduce thermal deformation and impr...
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The quasi-continuous-wave laser directed energy deposition (QCW-DED), a form of directed energy deposition (DED), has garnered growing interest in recent years due to its ability to reduce thermal deformation and improve the performance of manufactured components. However, the interaction between the quasi-continuouswave (QCW) laser and the molten pool surface, and its subsequent effects on the dynamics and morphology of the molten pool, is still not clear. In this work, a coupled ray-tracing computational fluid dynamics (CFD) model, which integrates a laser-powder interaction model and material deposition model, is developed to study the multi-physics coupling characteristics in QCW-DED process. The incident angle between the laser rays and molten pool surface was quantified and the corresponding laser absorptivity was analyzed. After accounting for the influence of laser-surface interaction, the heat transfer and fluid dynamics within the molten pool were subsequently investigated. Several dimensionless numbers, including the Fourier number (Fo), Peclet number (Pe), Marangoni number (Ma), and Grashof number (Gr), were employed to elucidate the physical mechanisms underlying the evolution of the molten pool. The results show that the heat transfer within the molten pool is controlled alternately by thermal convection and thermal conduction during the QCW-DED process. Furthermore, the Marangoni effect and buoyancy effect are weaker in the QCW-DED process compared to the continuous-wave laser directed energy deposition (CW-DED) process. However, the molten pool has a stronger heat dissipation capability in the QCW-DED process. Finally, the calculated molten pool geometry shows good agreement with the experimental results with the relative error less than 14.5%. This work provides a deeper insight into laser-surface interaction and the dynamics behavior within the molten pool during the QCW-DED process. The developed model can also serve as a fundamental tool for unde
PurposeAccurately quantifying the rupture risk of unruptured intracranial aneurysms (UIAs) is crucial for guiding treatment decisions and remains an unmet clinical challenge. Computational Flow dynamics and morphologi...
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PurposeAccurately quantifying the rupture risk of unruptured intracranial aneurysms (UIAs) is crucial for guiding treatment decisions and remains an unmet clinical challenge. Computational Flow dynamics and morphological measurements have been shown to differ between ruptured and unruptured aneurysms. It is not clear if these provide any additional information above routinely available clinical observations or not. Therefore, this study investigates whether incorporating image-derived features into the established PHASES score can improve the classification of aneurysm rupture *** cross-sectional dataset of 170 patients (78 with ruptured aneurysm) was used. Computational fluid dynamics (CFD) and shape analysis were performed on patients' images to extract additional features. These derived features were combined with PHASES variables to develop five ridge constrained logistic regression models for classifying the aneurysm rupture status. Correlation analysis and principal component analysis were employed for image-derived feature reduction. The dataset was split into training and validation subsets, and a ten-fold cross validation strategy with grid search optimisation and bootstrap resampling was adopted for determining the models' coefficients. Models' performances were evaluated using the area under the receiver operating characteristic curve (AUC).ResultsThe logistic regression model based solely on PHASES achieved AUC of 0.63. All models incorporating derived features from CFD and shape analysis demonstrated improved performance, reaching an AUC of 0.71. Non-sphericity index (shape variable) and maximum oscillatory shear index (CFD variable) were the strongest predictors of a ruptured *** study demonstrates the benefits of integrating image-based fluid dynamics and shape analysis with clinical data for improving the classification accuracy of aneurysm rupture status. Further evaluation using longitudinal data is needed to assess th
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