Article
Mechanics
Fuqi Li, Peng Wang, Yingzheng Liu
Summary: Turbulent flow through tandem orifices in a circular duct is numerically modeled to understand the unsteady flow behaviors and noise generation mechanism. Different configurations with varying separation distances are compared, and the acoustic sources and their noise propagation are analyzed. The flow structures and noise mechanisms are determined using spectral proper orthogonal decomposition. The dominant noise sources are alternating acoustic dipoles on the leading and trailing faces of the orifice, and the total sound pressure level is influenced by shedding behaviors and wavepackets.
Article
Mechanics
Giancarlo Lenci, Jinyong Feng, Emilio Baglietto
Summary: This work presents a strategy for hybrid turbulence modeling based on flow structure parameters to reduce modeling error by adjusting scale resolution. By increasing scale resolution inside rapidly deformed turbulence areas, improved accuracy can be achieved compared to basic URANS closures.
Article
Engineering, Mechanical
Ren-Kun Han, Zhong Zhang, Yi-Xing Wang, Zi-Yang Liu, Yang Zhang, Gang Chen
Summary: A new reduced order model based on hybrid deep neural network is proposed to model flow field evolution around moving boundary. By simulating various unsteady flows, the model shows high accuracy and can be applied in fluid dynamics research fields requiring fast and accurate simulation.
ACTA MECHANICA SINICA
(2021)
Article
Engineering, Aerospace
Nicholas J. Peters, Andrew Wissink, John Ekaterinaris
Summary: This study investigates the construction of reduced order models (ROMs) for store separation from aircraft and spacecraft. Results indicate that proper orthogonal decomposition (POD) performs most efficiently for load prediction, while surface splines and Kriging interpolation provide accurate and fast load predictions for oscillating store cases. The ROM-based surrogate model constructed can accurately predict store trajectories under intermediate conditions.
AEROSPACE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Aerospace
Chao Pang, Zhenghong Gao, Hua Yang, Shusheng Chen
Summary: A simplified grid assembling method for the unsteady dynamic overset grid method is proposed in this work, utilizing the difference value of the grid position and a specially designed grid system to simplify the traditional grid assembling method. Three test cases demonstrate the high efficiency and accuracy of the proposed method, saving more than 85% of computational time spent on the grid assembling process. This method is potentially a better candidate for unsteady motion simulation using overset grid.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Najiyah Safwa Khashi'ie, Iskandar Waini, Nurul Amira Zainal, Khairum Bin Hamzah, Abdul Rahman Mohd Kasim, Norihan Md Arifin, Ioan Pop
Summary: This paper examines the unsteady separated stagnation point flow and thermal progress of Fe3O4-CoFe2O4/H2O on a moving plate, and finds that the magnetic and acceleration parameters enhance skin friction and heat transfer coefficients. However, increasing the heat generation parameter leads to a reduction in the thermal rate distribution, indicating the greater effectiveness of heat absorption compared to heat generation in the thermal flow process.
Article
Mechanics
Gaurav Kumar, Ashoke De
Summary: This study investigates the origin and sustenance of self-induced oscillations of shock structures in hypersonic flow over a double wedge configuration, revealing the significant impact of shock position on flow stability.
Article
Physics, Multidisciplinary
Ahmer Mehmood, Babar Hussain Shah, Muhammad Usman, Iqrar Raza
Summary: Theoretical investigations of fundamental boundary-layer flows are always given prime importance. Flows due to moving continuous surfaces offer richer physics and more technological applications compared to flows over surfaces of finite length, and are more useful in delaying flow separation.
Article
Thermodynamics
Ahmad H. Milyani, Nidal H. Abu-Hamdeh, Abdullah A. Azhari, Hussein A. Z. AL-bonsrulah, Amira M. Hussin
Summary: This article achieved improvement in the rate of freezing by utilizing porous containers and hybrid nanomaterials. The effects of different factors on the freezing process were analyzed through numerical simulations.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Engineering, Aerospace
Wei Song, Jingang Dong, Wei Lu, Zenghui Jiang
Summary: The wind tunnel tests evaluate the deviations of trajectory and attitude angle for internal store separation using two different methods, showing that the outcome can be influenced by the initial pitch angular velocity. The unsteady method and quasi-steady method yield different pitch angles for the store separation event, indicating the unpredictability caused by highly unsteady flow.
CHINESE JOURNAL OF AERONAUTICS
(2022)
Article
Engineering, Mechanical
Yunqing Gu, Junjun Zhang, Songwei Yu, Chengqi Mou, Zhou Li, Chendong He, Denghao Wu, Jiegang Mou, Yun Ren
Summary: In this study, the grid irrelevance and discrete error in hydrofoil unsteady cavitation simulations were investigated using the GCI evaluation method to determine the optimal number of grids. Various turbulent viscosity correction approaches were employed to improve the turbulence model, and numerical simulations successfully captured the details of the hydrofoil cavity shape and shedding process, revealing the mechanism of hydrofoil cavitation.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Mechanics
Xiaozhi Kong, Dongzhi Ren, Peng Zhang, Shuang Guo, Huawei Lu
Summary: This study investigates the adaptability of the end wall unsteady pulsed jet (UPJ) at different incidence angles and compares it with the traditional steady constant jet (SCJ). Numerical simulations show that the UPJ has a significantly superior control effect compared to the SCJ for the design incidence angle and time-averaged jet flow. The UPJ reduces total-pressure loss coefficient and increases static-pressure-rise coefficient, resulting in improved cascade aerodynamic performance.
Article
Engineering, Aerospace
Hua-feng Xu, Sheng-feng Zhao, Ming-yang Wang, Xiao-Ying Sheng, Ge Han, Xin-gen Lu
Summary: This study utilizes experimentally validated Large Eddy Simulation method and Dynamic Mode Decomposition analysis technique to investigate the unsteady flow characteristics on a compressor cascade under different Reynolds number conditions. The results show that at low Reynolds number, large-scale vortices dominate the flow, while at high Reynolds number, vortices become dispersed and smaller. The study also reveals the significant roles of Kelvin-Helmholtz instability and harmonic instability in the flow.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Mechanics
Lakshya Kumar, Dilipkumar Bhanudasji Alone, A. M. Pradeep
Summary: This study investigates the evolution of dominant secondary flow structures in the rotor and stator of a transonic compressor stage, and validates the performance characteristics through numerical analysis and experimental data. The presence of rotor tip shock intensifies tip leakage flow and boundary layer separation, while the stator is influenced by asymmetric hub corner separation and tip corner separation. The findings provide a better understanding of the aerodynamic instabilities in the compressor stage.
Article
Thermodynamics
Nurul Amira Zainal, Roslinda Nazar, Kohilavani Naganthran, Ioan Pop
Summary: This study numerically investigates the unsteady stagnation-point flow past a stretching/shrinking horizontal cylinder, considering the impact of a magnetic field. The results indicate that increasing the concentration of nanoparticles and altering the mixing ratio can enhance heat transfer efficiency, while increasing the magnetic parameter leads to a decrease in heat transfer rate.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Computer Science, Interdisciplinary Applications
Jin Bao, Zhaoli Guo
Summary: At the equilibrium state of a two-phase fluid system, the chemical potential is constant and the velocity is zero. However, it is challenging to capture this equilibrium state accurately in numerical simulations, resulting in inconsistent thermodynamic interfacial properties and spurious velocities. Therefore, numerical schemes with well-balanced properties are preferred for simulating two-phase flows.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Brian C. Vermeire
Summary: This study presents a framework for implicit large eddy simulation (ILES) of incompressible flows by combining the entropically damped artificial compressibility (EDAC) method with the flux reconstruction (FR) approach. Experimental results demonstrate that the method is accurate and stable for low-order solutions, while higher-order solutions exhibit significantly higher accuracy and lower divergence error compared to reference direct numerical simulation.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Mijian Li, Rui Wang, Xinyu Guo, Xinyu Liu, Lianzhou Wang
Summary: In this study, the flow mechanisms around wall-mounted structures were investigated using Large Eddy Simulation (LES). The impact of inflow turbulence on the flow physics, dynamic response, and hydrodynamic performance was explored. The results revealed strong interference between velocity fluctuations and the wake past the cylinder, as well as significant convection effects in the far wake region.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Donatella Passiatore, Luca Sciacovelli, Paola Cinnella, Giuseppe Pascazio
Summary: A high-order shock-capturing central finite-difference scheme is evaluated for numerical simulations of hyper-sonic high-enthalpy flows out of thermochemical equilibrium. The scheme utilizes a tenth-order accurate central-difference approximation of inviscid fluxes, along with high-order artificial dissipation and shock-capturing terms. The proposed approach demonstrates accuracy and robustness for a variety of thermochemical non-equilibrium configurations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Philipp Bahavar, Claus Wagner
Summary: Condensation is an important aspect in flow applications, and simulating the gas phase and tracking the deposition rates of condensate droplets can capture the effects of surface droplets on the flow while reducing computational costs.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andras Szabo, Gyorgy Paal
Summary: This paper introduces an efficient calculation method, the parabolized stability equations (PSE), for solving stability equations. By calculating LU factorization once in each marching step, the time spent on solving linear systems of equations can be significantly reduced. Numerical experiments demonstrate the effectiveness of this method in reducing the solution time for linear equations, and its applicability to similar problems.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
A. Khalifa, M. Breuer
Summary: This study evaluates a recently developed data-driven model for collision-induced agglomerate breakup in high mass loading flows. The model uses artificial neural networks to predict the post-collision behavior of agglomerates, reducing computational costs compared to coupled CFD-DEM simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Chunmei Du, Maojun Li
Summary: This paper considers the bilayer shallow water wave equations in one-dimensional space and presents an invariant domain preserving DG method to avoid Kelvin-Helmholtz instability.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jean-Michel Tucny, Mihir Durve, Andrea Montessori, Sauro Succi
Summary: The prediction of non-equilibrium transport phenomena in disordered media is a challenging problem for conventional numerical methods. Physics-informed neural networks (PINNs) show potential for solving this inverse problem. In this study, PINNs were used to successfully predict the velocity field of rarefied gas flow, and AdamW was found to be the best optimizer.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Min Gao, Pascal Mossier, Claus-Dieter Munz
Summary: In recent decades, the arbitrary Lagrangian-Eulerian (ALE) approach has gained popularity in dealing with fluid flows with moving boundaries. This paper presents a novel algorithm that combines the ALE finite volume (FV) and ALE discontinuous Galerkin (DG) methods into a stable and efficient hybrid approach. The main challenge of this mixed ALE FV and ALE DG method is reducing the inconsistency between the two discretizations. The proposed algorithm is implemented into a loosely-coupled fluid-structure interaction (FSI) framework and is demonstrated through various benchmark test cases and complex scenarios.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Dawid Strzelczyk, Maciej Matyka
Summary: In this study, the numerical convergence of the Meshless Lattice Boltzmann Method (MLBM) is investigated through three benchmark tests. The results are compared to the standard Lattice Boltzmann Method (LBM) and the analytical solution of the Navier-Stokes equation. It is found that MLBM outperforms LBM in terms of error value for the same number of nodes discretizing the domain.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Kanishka Bhattacharya, Tapan Jana, Amit Shaw, L. S. Ramachandra, Vishal Mehra
Summary: In this work, an adaptive algorithm is developed to address the issue of tensile instability in Smoothed Particle Hydrodynamics (SPH) by adjusting the shape of the kernel function to satisfy stability conditions. The effectiveness of the algorithm is demonstrated through dispersion analysis and fluid dynamics simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Luis Laguarda, Stefan Hickel
Summary: We propose several enhancements to improve the accuracy and performance of the digital filter turbulent inflow generation technique, such as introducing a more realistic correlation function and varying target length scales. Additionally, we suggest generating inflow data in parallel at a prescribed time interval to improve computational performance. Based on the results of large-eddy simulations, these enhancements have shown to be beneficial. Suppressing streamwise velocity fluctuations at the inflow leads to the fastest relaxation of pressure fluctuations. However, this approach increases the adaptation length, which can be shortened by artificially increasing the wall-normal Reynolds stresses.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Constantin Zenz, Michele Buttazzoni, Tobias Florian, Katherine Elizabeth Crespo Armijos, Rodrigo Gomez Vazquez, Gerhard Liedl, Andreas Otto
Summary: A new model for compressible multiphase flows involving sharp interfaces and phase change is presented, with a focus on the treatment of compressibility and phase change in the multiphase fluid flow model. The model's accuracy and suitability are demonstrated through comparisons with experimental observations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Joseph O'Connor, Sylvain Laizet, Andrew Wynn, Wouter Edeling, Peter V. Coveney
Summary: This article aims to apply uncertainty quantification and sensitivity analysis to the direct numerical simulation (DNS) of low Reynolds number wall-bounded turbulent channel flow. By using a highly scalable DNS framework and UQ techniques, the study evaluates the influence of different numerical parameters on the simulation results without explicitly modifying the code. The findings provide guidance for numerical simulations of wall-bounded turbulent flows.
COMPUTERS & FLUIDS
(2024)