Article
Engineering, Aerospace
Xiang Ren, Hua Su, Hua-Hua Yu, Zheng Yan
Summary: Considering the grid requirements of high Reynolds flow, wall-modeled large eddy simulation (WMLES) and detached eddy simulation (DES) have become the main methods for near-wall turbulence. This study verifies the accuracy of the WMLES, SST-DES, and SA-DES methods in predicting flow separation and wake characteristics in three different separated flows. The results show that the methods can predict separation position accurately, but depend on grid scale and turbulent inflow for accurate simulation of certain flows.
Article
Computer Science, Interdisciplinary Applications
F. Gand, M. Huet
Summary: This study evaluates a low-noise turbulence generation method to produce three-dimensional resolved turbulence at the exit of a jet nozzle. Combining the turbulence generation method with ZDES mode 3 produces satisfying levels of resolved turbulence. In comparison, ZDES mode 2 simulations display quick development of three-dimensional turbulence in the mixing layer. These results provide insights on the level of turbulent modeling needed for jet flow simulations.
COMPUTERS & FLUIDS
(2021)
Article
Thermodynamics
Stefan Heinz
Summary: This paper discusses the importance of hybrid RANS-LES methods in analyzing and predicting wall-bounded turbulent flows at high Reynolds numbers, while pointing out that validation data is often unavailable. The paper analyzes options for the formulation of hybrid RANS-LES, supporting the further development of continuous eddy simulation methods.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Engineering, Chemical
Abdel Dehbi, Bojan Niceno, Konstantin Mikityuk, Mohamed Aly Sayed
Summary: Particle dispersion in a periodic channel is studied using the elliptic relaxation hybrid RANS/LES (ER-HRL) model. The model employs a four-equation linear eddy viscosity (LEV) model near the wall and switches to the LES Smagorinsky dynamic model in the outer flow region. A systematic analysis of particle dispersion is performed for different Stokes numbers and shear Reynolds numbers, and a novel subgrid-scale model is proposed to account for the effect of unresolved scales. The model is validated against DNS and LES databases, showing good agreement, and outperforms the LES subgrid stochastic acceleration approach for higher Reynolds numbers.
Article
Computer Science, Interdisciplinary Applications
Ashutosh Kumar Jaiswal, Anupam Dewan, Amitabh Bhattacharya
Summary: Scale-resolving hybrid RANS-LES models are efficient and accurate for numerically simulating wall-bounded turbulent flows. The interpolated RANS-LES solver, implemented in OpenFOAM, simultaneously evolves the RANS equations and LES equations on the same computational grid. By interpolating the turbulent eddy-viscosity, the solver corrects the mean subgrid stress and accurately predicts resolved Reynolds stresses.
COMPUTERS & FLUIDS
(2023)
Article
Thermodynamics
Mehran Masoumifar, Suyash Verma, Arman Hemmati
Summary: The study investigated the response of three-dimensional turbulent pipe flow at high Reynolds numbers under targeted wall conditions. Different wall shapes were found to result in prolonged changes in flow properties and varied recovery trends, with higher Fourier mode wall shapes showing longer recovery lengths and non-monotonic response characteristics.
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW
(2021)
Article
Thermodynamics
Emmanuel Gillyns, Sophia Buckingham, Gregoire Winckelmans
Summary: In this study, the near-wall layer is modeled using an algebraic wall model in large eddy simulations (LES) to simulate high Reynolds number turbulent flows. The model is implemented in the Nek5000 code and applied to channel flow cases at different Reynolds numbers. The results show good agreement with reference direct numerical simulations and provide guidelines for accurate simulation at a reduced cost.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Engineering, Multidisciplinary
Lei Xie, Qiang Du, Guang Liu, Zengyan Lian, Yaguang Xie, Yifu Luo
Summary: Rotor-stator cavities in gas turbine engines are often exposed to highly swirled external crossflow and are sealed by a sealing flow to prevent hot mainstream gas ingress. The interactions between the external crossflow, cavity flow, and sealing flow involve turbulent unsteadiness and flow instability, which cannot be accurately resolved by the Reynolds-average approach. In this study, a wall-modeled large-eddy simulation (WMLES) approach is used to simulate the flow field and analyze the deviations between the RANS and WMLES results. The results show distinct deviations in both small and large-radius regions, caused by the inadequate capturing of small-scale vortex structures and the prediction of external crossflow ingestion, respectively. The boundary layer vortex and external ingestion are discussed in detail, along with the analysis of large-flow structures induced by external flow ingress using unsteady pressure oscillation signals.
JOURNAL OF ZHEJIANG UNIVERSITY-SCIENCE A
(2023)
Article
Construction & Building Technology
Muhamed Hadziabdic, Mahir Hafizovic, Bojan Niceno, Kemal Hanjalic
Summary: This study reports on the application and comparative assessment of two rational turbulence modelling approaches for simulating air flow and pollutant dispersion in urban environments. The results show that the accuracy and credibility of predictions can be substantially improved by using a physically sound and relatively simple eddy-viscosity model that specifically accounts for the elliptic inviscid wall-blocking effects and near-wall stress anisotropy in complex urban shapes and arrangements.
BUILDING AND ENVIRONMENT
(2022)
Article
Engineering, Multidisciplinary
Ruiyu Li, Lei Zhao, Ning Ge, Limin Gao, Mingjiu Ni
Summary: Hybrid RANS-LES is a promising method for analyzing complex flow structures in turbomachinery, and this work proposes a novel grid resolution evaluation method suitable for both LES and URANS, which can reduce uncertainty and improve reliability.
ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS
(2022)
Article
Engineering, Aerospace
Patrick Kopper, Marius Kurz, Christoph Wenzel, Jakob Duerrwaechter, Christian Koch, Andrea Beck
Summary: Modern turbomachinery relies on accurate prediction of flow and turbulence state to achieve performance, with large eddy simulation (LES) offering improved accuracy over Reynolds-averaged Navier-Stokes (RANS) methods. This paper characterizes the boundary-layer state using high-order discontinuous Galerkin spectral element method for wall-resolved LES, comparing performance characteristics with experimental and numerical data. The temporal evolution of the solution and spatiotemporal turbulence near the blade surface are analyzed to provide insights into turbulence development.
Article
Engineering, Multidisciplinary
Luis F. N. Sa, Paulo V. M. Yamabe, Bruno C. Souza, Emilio C. N. Silva
Summary: The research focuses on the design and optimization of rotating fluid devices under high Reynolds numbers, using a modified SA model and density-based material model. The analysis considers the Rotation/Curvature Correction for improved turbulence evaluation in rotating frames. Multiple optimized topologies are demonstrated for rotating flows with different domains and angular velocities.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Nuclear Science & Technology
U. Bieder, H. Uitslag-Doolaard, B. Mikuz
Summary: Experimental analysis of hexagonal assemblies of wire-wrapped fuel rods was conducted at Texas A&M University. The study showed that RANS models overestimated the pressure loss in wire wrapped rod bundles.
ANNALS OF NUCLEAR ENERGY
(2021)
Article
Mechanics
Mohammad Kazemi, Babak Khorsandi, Laurent Mydlarski
Summary: The dynamics and mixing of circular turbulent wall jets released into both quiescent and coflowing streams were experimentally investigated. The presence of a coflow was found to reduce the decay rate, spreading rate, and mean lateral velocities of wall jets, indicating decreased entrainment and mixing. The wall jets issued into a coflow also developed more slowly and reached self-similarity at farther downstream distances. Additionally, the root-mean-square velocities of the wall jets increased when a coflow was present.
Article
Physics, Fluids & Plasmas
Zhideng Zhou, Guowei He, Xiaolei Yang
Summary: A data-driven wall model for turbulent flows over periodic hills is developed using feedforward neural network (FNN) and wall-resolved large-eddy simulation (WRLES) data. The FNN predictions show good agreement with WRLES data for the wall shear stresses, but some discrepancies are observed near the crest of the hill. Overall, the correlation coefficients between FNN predictions and WRLES predictions are larger than 0.7 at most streamwise locations.
PHYSICAL REVIEW FLUIDS
(2021)
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)