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Journal articles on the topic 'Unsteady simulation'

Author: Grafiati

Published: 28 June 2021

Last updated: 29 July 2025

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1

Torner, Benjamin, Lucas Konnigk, Sebastian Hallier, Jitendra Kumar, Matthias Witte, and Frank-Hendrik Wurm. "Large eddy simulation in a rotary blood pump: Viscous shear stress computation and comparison with unsteady Reynolds-averaged Navier–Stokes simulation." International Journal of Artificial Organs 41, no. 11 (2018): 752–63. http://dx.doi.org/10.1177/0391398818777697.

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Purpose: Numerical flow analysis (computational fluid dynamics) in combination with the prediction of blood damage is an important procedure to investigate the hemocompatibility of a blood pump, since blood trauma due to shear stresses remains a problem in these devices. Today, the numerical damage prediction is conducted using unsteady Reynolds-averaged Navier–Stokes simulations. Investigations with large eddy simulations are rarely being performed for blood pumps. Hence, the aim of the study is to examine the viscous shear stresses of a large eddy simulation in a blood pump and compare the r

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2

Wang, Zhi Gang, and Zhen Ning Zhang. "Modeling and Simulation of Unsteady Aerodynamics on a Morphing Wing." Applied Mechanics and Materials 427-429 (September 2013): 77–80. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.77.

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Modeling and simulation method of unsteady aerodynamics on morphing wings were investigated. The Unsteady Vortex Lattice Method is employed to model the unsteady aerodynamics of 3-D potential flow field surrounding the wing. An UVLM computer code was then developed and validated for numerical simulation. A morphing wing which changes its dihedral angle with constant angular velocity was investigated by the code, and the lift, induced drag, and pitching moment coefficients time histories were obtained. The results show that the UVLM code is an effective tool for simulations of unsteady aerodyna

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3

Adamczyk, J. J., M. L. Celestina, and Jen Ping Chen. "Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification." Journal of Turbomachinery 118, no. 1 (1996): 88–95. http://dx.doi.org/10.1115/1.2836611.

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The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three-dimensional unsteady viscous flow code. The results from this simulation are used to define two steady-state inlet conditions for a three-dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the

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4

Wang, Ziwei, Xiong Jiang, Ti Chen, Yan Hao, and Min Qiu. "Numerical simulation of transonic compressor under circumferential inlet distortion and rotor/stator interference using harmonic balance method." Modern Physics Letters B 32, no. 12n13 (2018): 1840021. http://dx.doi.org/10.1142/s0217984918400213.

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Simulating the unsteady flow of compressor under circumferential inlet distortion and rotor/stator interference would need full-annulus grid with a dual time method. This process is time consuming and needs a large amount of computational resources. Harmonic balance method simulates the unsteady flow in compressor on single passage grid with a series of steady simulations. This will largely increase the computational efficiency in comparison with the dual time method. However, most simulations with harmonic balance method are conducted on the flow under either circumferential inlet distortion

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Sznajder, Janusz, and Jerzy Zółtak. "APPLICATION OF AN EULER SOLVER TO SELECTED PROBLEMS IN FLIGHT DYNAMICS." Aviation 11, no. 2 (2007): 13–22. http://dx.doi.org/10.3846/16487788.2007.9635956.

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Several applications of a Euler solver with the formulation of the flow equations in the noninertial reference system with steady and unsteady flow analysis are presented. The steady‐flow applications include determination of aerodynamic derivatives with respect to angular velocity and analysis of vortical flow over a delta wing at high angles of attack with the determination of aerodynamic coefficients and analysis of vortex breakdown. The unsteady flow analysis is applied in the simulation of a rapid manoeuvre for the determination of unsteady forces. The results of this simulation are compa

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Hu, Le, Shu Jia Zhang, and Cheng Xu. "The Use of Steady Multi-Phase Position and Unsteady Computational Methods in the Numerical Simulation of Double-Suction Centrifugal Pump." Advanced Materials Research 181-182 (January 2011): 201–5. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.201.

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In order to compare the steady multi-phase and unsteady calculation in double-suction centrifugal pump application, this article simulates the internal turbulent flow of the 150S-50 double suction centrifugal pump. Numerical simulation uses realizable turbulence model, simulating with two methods of steady multi-phase and unsteady in 7 cases. Based on the numerical simulation, the head, shaft power, efficiency were calculated, the simulated performance curves of a double suction centrifugal pump is processed. The results show that: The results of unsteady simulation are closer with the experim

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7

Münsterjohann, Sven, Jens Grabinger, Stefan Becker, and Manfred Kaltenbacher. "CAA of an Air-Cooling System for Electronic Devices." Advances in Acoustics and Vibration 2016 (October 20, 2016): 1–17. http://dx.doi.org/10.1155/2016/4785389.

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This paper presents the workflow and the results of fluid dynamics and aeroacoustic simulations for an air-cooling system as used in electronic devices. The setup represents a generic electronic device with several electronic assemblies with forced convection cooling by two axial fans. The aeroacoustic performance is computed using a hybrid method. In a first step, two unsteady CFD simulations using the Unsteady Reynolds-Averaged Navier-Stokes simulation with Shear Stress Transport (URANS-SST) turbulence model and the Scale Adaptive Simulation with Shear Stress Transport (SAS-SST) models were

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Grioni, Mauro, Sergio Elaskar, Pascal Bruel, and Anibal Mirasso. "Numerical Simulation of Turbulent Flows using the SST-SAS Model." WSEAS TRANSACTIONS ON FLUID MECHANICS 19 (January 29, 2024): 24–39. http://dx.doi.org/10.37394/232013.2024.19.3.

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Turbulent flows play a crucial role in various engineering and scientific applications, and the accurate prediction of these flows remains a challenging task. This review explores the application of the Shear Stress Transport Scale-Adaptive Simulation (SST-SAS) turbulence model for solving incompressible turbulent flows, with a specific focus on unsteady wakes behind bluff bodies. Providing a concise overview of the model’s formulation and its advantages, this article highlights the efficacy of the SST-SAS model in simulating the intricate dynamics in different configurations of circular cylin

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9

Salehian, Saman, and Reda R. Mankbadi. "Simulations of rocket launch noise suppression with water injection from impingement pad." International Journal of Aeroacoustics 19, no. 3-5 (2020): 207–39. http://dx.doi.org/10.1177/1475472x20930653.

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The focus of this work is on understanding the effect of water injection from the launch pad on the noise generated during rocket’s lift-off. To simplify the problem, we consider a supersonic jet impinging on a flat plate with water injection from the impingement plate. The Volume of Fluid model is adopted in this work to simulate the two-phase flow. A Hybrid Large Eddy Simulation – Unsteady Reynolds Averaged Simulation approach is employed to model turbulence, wherein Unsteady Reynolds Averaged Simulation is used near the walls, and Large Eddy Simulation is used elsewhere in the computational

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10

Sharma, O. P., G. F. Pickett, and R. H. Ni. "Assessment of Unsteady Flows in Turbines." Journal of Turbomachinery 114, no. 1 (1992): 79–90. http://dx.doi.org/10.1115/1.2928001.

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The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

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Zhao, Xiaoran, Zhengwei Wang, Yexiang Xiao, and Yongyao Luo. "Thermodynamic analysis of energy dissipation and unsteady flow characteristic in a centrifugal dredge pump under over-load conditions." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 13 (2019): 4742–53. http://dx.doi.org/10.1177/0954406218824350.

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The present paper aims to investigate the energy dissipation related to unsteady flow phenomena inside a three-bladed impeller of a centrifugal dredge pump under over-load operating conditions. Three-dimensional unsteady numerical simulations of the centrifugal pump are performed by adopting the SAS SST-curvature correction turbulence model with the total energy equation. The simulating results are verified by comparing the performance results and pressure fluctuation with available experimental data. The unsteady flow patterns and energy dissipation in the rotating impeller are analysed by en

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12

Feng, Guang, Wei-zheng Chen, Xue-sen Chu, Zhi Wang, Ming-hui Zhang, and Wei-qi Chen. "Simulation of unsteady artificial supercavities." Journal of Hydrodynamics 22, S1 (2010): 862–68. http://dx.doi.org/10.1016/s1001-6058(10)60050-9.

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13

LI, WEI, ZHONGYONG PAN, and WEIDONG SHI. "NUMERICAL INVESTIGATION OF PUMP-TURBINES WITH DIFFERENT BLADES AT PUMP CONDITIONS." Journal of Advanced Manufacturing Systems 11, no. 02 (2012): 143–50. http://dx.doi.org/10.1142/s0219686712500138.

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The undesirable performance of a positive slope curve usually appears for pump-turbines running as pumps at a low flow rate. The inner flow feature of pump-turbines with 6- and 7-blades runner is studied by both steady and unsteady simulations at pump conditions. According to the steady simulation investigation, obviously back flow vortex is found in the runner passage at the low flow rate zone where the positive slope curve forms. The flow rate at which the instable flow pattern happens of 6-blades runner is smaller than that of 7-blades one. By the unsteady simulation, at the low flow rate z

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14

Kumar, Dinesh, Vikash Kumar, Kailash Jha, and Lakhbir Singh Brar. "The effect of different subgrid-scale models on the flow field in cyclone separator using large-eddy simulations: A benchmark study." Journal of Physics: Conference Series 2856, no. 1 (2024): 012001. http://dx.doi.org/10.1088/1742-6596/2856/1/012001.

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Abstract The cyclone separator is extensively utilized across industries to extract solid particles from gas streams. This study is focused on the steady and unsteady simulations of the Stairmand cyclone using large-eddy simulations aiming to assess the performance using different subgrid-scale models viz. standard Smagorinsky (Cs =1), dynamic Smagorinsky, Wall-Adapting Local Eddy-Viscosity (WALE), Wall-Modeled LES (WMLES), and dynamic kinetic energy models. The velocity profiles within the cyclone separator were analyzed under both steady and unsteady conditions, with reference to the Hoekstr

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15

Luo, Bo, Wuli Chu, Song Yan, Zhengjing Shen, and Haoguang Zhang. "Assessment of improved delayed detached eddy simulation in predicting unsteady flows and sound around a circular cylinder." Modern Physics Letters B 35, no. 23 (2021): 2150384. http://dx.doi.org/10.1142/s021798492150384x.

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Unsteady flows in the field of engineering are usually calculated by the Unsteady Reynolds-Averaged Navier–Stokes (URANS) owing to the low requirements for computational efforts. However, the numerical resolution of URANS, especially in predicting the unsteady wake flows and sound, is still questionable. In this work, unsteady flow and sound calculations of a circular cylinder are carried out using Improved Delayed Detached Eddy Simulation (IDDES) and the Ffowcs Williams–Hawkings (FW-H) analogy. The predicted results of this calculation are compared with those from the previous studies in the

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16

Yao, Zhen Qiu, and Cheng Long Yang. "Numerical Simulation of Unsteady Flow for Variable-Pitch Vertical Axis Wind Turbine." Applied Mechanics and Materials 291-294 (February 2013): 490–95. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.490.

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Using computational fluid dynamics (CFD) software Fluent, numerical simulation for unsteady flow around the vertical axis wind turbine (VAWT) was performed, which was based on the UDF controlled sliding meshes method. And SST k-ω turbulent model and SIMPLE algorithm were used to solve the unsteady incompressible N-S equation. Velocity magnitude profile, pressure, the blade force and the torque had been obtained by doing this. The result shows this method can effectively simulate the unsteady flow field performance of the variable-pitch vertical axis wind turbine, and it provides a new method f

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17

Guo, Zhong-Zhou, Gang Dai, Hua Yang, and Wei-Fang Chen. "Unsteady flow simulation of a variable-sweep morphing aircraft coupled with flight control system." International Journal of Modern Physics B 34, no. 14n16 (2020): 2040073. http://dx.doi.org/10.1142/s0217979220400731.

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Morphing aircraft has adjustable aerodynamic shapes and is suitable for variable flight conditions. And there have been growing interests in recent years. However, the forces and moments are highly nonlinear, bringing challenges in design and modeling of flight control system (FCS). In this paper, unsteady Computational Fluid Dynamics (CFD) simulations are performed by solving the Arbitrary Lagrangian–Eulerian (ALE) governing equations on unstructured dynamic mesh, then unsteady aerodynamic characteristics of a variable-sweep morphing aircraft at hypersonic speed are acquired. The nonlinearity

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18

Michelassi, V., J. G. Wissink, and W. Rodi. "Direct numerical simulation, large eddy simulation and unsteady Reynolds-averaged Navier—Stokes simulations of periodic unsteady flow in a low-pressure turbine cascade: A comparison." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 217, no. 4 (2003): 403–11. http://dx.doi.org/10.1243/095765003322315469.

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The unsteady periodic flow in a low-pressure (LP) prismatic turbine vane with incoming wakes is computed by direct numerical simulation (DNS), large eddy simulation (LES) and unsteady Reynolds-averaged Navier—Stokes simulations (URANSs). The results are compared with existing measurements at a Reynolds number Re = 5.18 × 104 which reveal the presence of a large unsteady stalled region on the suction side. Both DNS and LES suggest that the boundary layer separates while being still laminar, with subsequent turbulent reattachment. Several URANSs with and without a transition model and a constrai

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19

Chen, Ming Zhou, and Qi Dou Zhou. "Numerical Simulation of Fluctuating Propeller Forces and Comparison with Experimental Data." Applied Mechanics and Materials 105-107 (September 2011): 518–22. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.518.

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Unsteady CFD method based on realizable k-ε model is used for predicting unsteady forces of propeller working in non-uniform wake. First, CFD computations with different mesh scales were conducted at the propeller design condition, the results show that mesh refinement changed the results little. Then unsteady CFD simulation with different time step intervals was conducted for determining suitable time step interval, the results show that it is suitable for propeller rotating 3° per step. Based on the chosen mesh and time step interval, unsteady CFD simulation of propeller P4118 was conducted

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20

Mao, Kun, Wuxing Jing, Meihong Zhang, and Huining Zhang. "An Aerodynamic Correction Technique for the Unsteady Subsonic Wing–Body Interference Model." Aerospace 10, no. 10 (2023): 837. http://dx.doi.org/10.3390/aerospace10100837.

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This paper investigates a novel correction technique for the unsteady subsonic wing–body interference model. The correction technique considers the unsteady forces on the lifting boxes and the body elements of an idealized aircraft model. The chosen simulation model was a passenger aircraft, and the transonic unsteady aerodynamics in sinusoidal pitch motion at four different frequencies are analyzed. The unsteady aerodynamics of the uncorrected DLM (doublet lattice method), ECFT (enhanced correction factor technique) and the new unsteady wing–body correction method are compared to the unsteady

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21

Petit, Olivier, and Håkan Nilsson. "Numerical Investigations of Unsteady Flow in a Centrifugal Pump with a Vaned Diffuser." International Journal of Rotating Machinery 2013 (2013): 1–14. http://dx.doi.org/10.1155/2013/961580.

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Computational fluid dynamics (CFD) analyses were made to study the unsteady three-dimensional turbulence in the ERCOFTAC centrifugal pump test case. The simulations were carried out using the OpenFOAM Open Source CFD software. The test case consists of an unshrouded centrifugal impeller with seven blades and a radial vaned diffuser with 12 vanes. A large number of measurements are available in the radial gap between the impeller and the diffuse, making this case ideal for validating numerical methods. Results of steady and unsteady calculations of the flow in the pump are compared with the exp

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22

SUZUKI, TAKAO, HUI JI, and FUJIO YAMAMOTO. "Instability waves in a low-Reynolds-number planar jet investigated with hybrid simulation combining particle tracking velocimetry and direct numerical simulation." Journal of Fluid Mechanics 655 (May 17, 2010): 344–79. http://dx.doi.org/10.1017/s0022112010000893.

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Instability waves in a laminar planar jet are extracted using hybrid unsteady-flow simulation combining particle tracking velocimetry (PTV) and direct numerical simulation (DNS). Unsteady velocity fields on a laser sheet in a water tunnel are measured with time-resolved PTV; subsequently, PTV velocity fields are rectified in a least squares sense so that the equation of continuity is satisfied, and they are transplanted to a two-dimensional incompressible Navier–Stokes solver by setting a multiple of the computational time step equal to the frame rate of the PTV system. As a result, the unstea

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23

Osnes, Andreas Nygård, and Magnus Vartdal. "Mach and Reynolds number dependency of the unsteady shock-induced drag force on a sphere." Physics of Fluids 34, no. 4 (2022): 043303. http://dx.doi.org/10.1063/5.0086399.

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Shock–particle interaction is an important phenomenon in a wide range of technological applications and natural phenomena, and the development of accurate models for this interaction is therefore of interest. This study investigates the transient forces during shock–particle interaction at particle Reynolds numbers between 100 and 1000, and incident shock wave Mach numbers between 1.22 and 2.51. This is achieved with the aid of particle-resolved large-eddy simulations. The simulation results show that shock–particle interaction differs qualitatively for subcritical and supercritical incident f

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24

Gao, Feng, Yanfeng Li, Zhihe Su, Chunlin Wang, Haidong Wang, and Junmei Li. "Optimal human respiratory simulation for exhaled gas based on CFD method." PLOS ONE 19, no. 11 (2024): e0313522. http://dx.doi.org/10.1371/journal.pone.0313522.

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Human breathing is crucial for studying indoor environments and human health. Computational Fluid Dynamics (CFD) is a key tool for simulating human respiration. To enhance the accuracy of CFD simulations and reduce computation time, a new simulation strategy for human respiration is proposed in this paper. The effects of steady versus unsteady boundary conditions on simulation results were examined. For the unsteady boundary, sinusoidal exhalation velocities and non-inhalation gas were assumed, while the steady boundary involved constant velocities during both exhalation and inhalation phases.

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Tang, Jing, Jian Zhang, Bin Li, and Nai-Chun Zhou. "Unsteady flow simulation with mesh adaptation." International Journal of Modern Physics B 34, no. 14n16 (2020): 2040080. http://dx.doi.org/10.1142/s0217979220400809.

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Mesh adaptation is a reliable and effective method to improve the precision of flow simulation with computational fluid dynamics. Mesh refinement is a common technique to simulate steady flows. In order to dynamically optimize the mesh for transient flows, mesh coarsening is also required to be involved in an iterative procedure. In this paper, we propose a robust mesh adaptation method, both refinement and coarsening included. A data structure of [Formula: see text]-way tree is adopted to save and access the parent–children relationship of mesh elements. Local element subdivision is employed

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Hassan, O., E. J. Probert, K. Morgan, and N. P. Weatherill. "Unsteady flow simulation using unstructured meshes." Computer Methods in Applied Mechanics and Engineering 189, no. 4 (2000): 1247–75. http://dx.doi.org/10.1016/s0045-7825(99)00376-x.

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27

Möller, S. I., E. Lundgren, and C. Fureby. "Large eddy simulation of unsteady combustion." Symposium (International) on Combustion 26, no. 1 (1996): 241–48. http://dx.doi.org/10.1016/s0082-0784(96)80222-0.

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28

Wang, Qiang, Wei Li, and Yongtao Yao. "Unsteady Coupled Heat Transfer Simulation of Unsteady numerical simulation of slot flow in anti-heating tile." IOP Conference Series: Earth and Environmental Science 651 (February 10, 2021): 022023. http://dx.doi.org/10.1088/1755-1315/651/2/022023.

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29

Lai, L. S., G. S. Djambazov, C. H. Lai, and K. A. Pericleous. "Comparison of Higher-Order Numerical Schemes and Several Filtering Methods Applied to Navier-Stokes Equations with Applications to Computational Aeroacoustics." Journal of Algorithms & Computational Technology 3, no. 3 (2009): 443–59. http://dx.doi.org/10.1260/174830108788251746.

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In computational acoustics, fluid-acoustic coupling methods for the computation of sound have been widely used by researchers for the last five decades. In the first part of the coupling procedure, the fully unsteady incompressible or compressible flow equations for the near-field of the unsteady flow are solved by using a Computational Fluid Dynamics (CFD) technique, such as Direct Numerical Simulation (DNS), Large Eddy Simulation (LES) or unsteady Reynolds averaged Navier-Stokes equations (RANS) the CFD predictions are then used to calculate sound sources using the acoustic analogy or solvin

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30

Shen, Xiaobin, Huanfa Wang, Guiping Lin, Xueqin Bu, and Dongsheng Wen. "Unsteady simulation of aircraft electro-thermal deicing process with temperature-based method." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (2019): 388–400. http://dx.doi.org/10.1177/0954410019866066.

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Considering the mass and energy sources carried by the accumulated ice layer, an unsteady heat and mass transfer model of the runback water film on the deicing surface is established to simulate aircraft electro-thermal deicing process. With the extension of the freezing coefficient to the transient calculation, the coupled heat transfer of the runback water and the solid skin is solved at each time step by a temperature-based method. Unsteady numerical simulation is carried out for the electro-thermal deicing system of a NACA 0012 airfoil. The temperature variations with time are in acceptabl

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Orihara, Hideo. "Comparison of CFD simulations with experimental data for a tanker model advancing in waves." International Journal of Naval Architecture and Ocean Engineering 3, no. 1 (2011): 1–8. http://dx.doi.org/10.2478/ijnaoe-2013-0040.

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ABSTRACTIn this paper, CFD simulation results for a tanker model are compared with experimental data over a range of wave conditions to verify a capability to predict the sea-keeping performance of practical hull forms. CFD simulations are conducted using WISDAM-X code which is capable of unsteady RANS calculations in arbitrary wave conditions. Comparisons are made of unsteady surface pressures, added resistance and ship motions in regular waves for cases of fully-loaded and ballast conditions of a large tanker model. It is shown that the simulation results agree fairly well with the experimen

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Bo¨lcs, A., T. H. Fransson, and M. F. Platzer. "Numerical Simulation of Inviscid Transonic Flow Through Nozzles With Fluctuating Back Pressure." Journal of Turbomachinery 111, no. 2 (1989): 169–80. http://dx.doi.org/10.1115/1.3262253.

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The study presents a numerical method, based on the flux vector splitting approach, to the problem of unsteady one-dimensional and two-dimensional inviscid transonic flows, with emphasis on the numerical determination of the shock position, through nozzles with time-varying back pressure. The model is first validated by comparison with exact (one dimension) and numerical (two dimensions) steady-state solutions. It is thereafter applied to the problem of time-fluctuating back pressure in quasi-one-dimensional and two-dimensional nozzles. The one-dimensional results are validated by comparison w

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Funazaki, K., N. Iwaguchi, and S. Kawasaki. "Unsteady flow simulations in two-stage turbines of a rocket turbopump to estimate blade structural soundness for fatigue." Journal of Physics: Conference Series 2217, no. 1 (2022): 012003. http://dx.doi.org/10.1088/1742-6596/2217/1/012003.

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Abstract This study first aims at detailed investigations of three-dimensional unsteady flow field in the reference and optimized rocket turbine stages by performing time-accurate flow simulations based on Transient Blade Row (TBR) method or Time Transformation (TT) method in a commercial software ANSYS CFX. Although TT method is believed to enable relatively low-cost unsteady flow simulation, detailed comparisons between TT method-based and conventional unsteady flow simulations are made before TT method application to Fluid-Structural Interaction (FSI) problem. This study then makes an attem

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Del Taglia, Christian, Lars Blum, Ju¨rg Gass, Yiannis Ventikos, and Dimos Poulikakos. "Numerical and Experimental Investigation of an Annular Jet Flow With Large Blockage." Journal of Fluids Engineering 126, no. 3 (2004): 375–84. http://dx.doi.org/10.1115/1.1760533.

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Unsteady 3-D numerical simulations and 3-D LDA measurements of an annular jet with a blockage ratio of 0.89 and Reynolds number 4400 are presented. At these flow conditions, the flow inside of the recirculation zone is asymmetric, with a preferential direction. Very good predictions of the velocity fluctuation values are achieved with the unsteady simulation technique in the same region, as the fluctuations are mainly large scale, structure dominated. A frequency near to 10 Hz is identified in the simulations, which is attributed to the principal shedding behavior of the vortical structures.

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Roos Launchbury, D., E. Casartelli, and L. Mangani. "Lattice Boltzmann simulation of the ERCOFTAC pump impeller." IOP Conference Series: Earth and Environmental Science 1079, no. 1 (2022): 012074. http://dx.doi.org/10.1088/1755-1315/1079/1/012074.

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Abstract The analysis of unsteady flows is becoming more and more important in the field of hydraulic turbomachinery applications, both for stable and especially for unstable operating conditions and other transient phenomena. Unsteady Reynolds-averaged Navier-Stokes (RANS) methods for incompressible flows, implemented via finite volume or finite element approaches, reach their limit in both accuracy and acceptable computational time. The accuracy mainly suffers due to the strong dependence of the solution on turbulence model variants. Furthermore, incompressibility of the flow and the linked

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Xiang, Xiao Jun, and Yu Qian. "Numerical Simulation of Unsteady Aerodynamic Loads over an Aircraft." Advanced Materials Research 908 (March 2014): 264–68. http://dx.doi.org/10.4028/www.scientific.net/amr.908.264.

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The unsteady aerodynamic loads are the basic of the aeroelastic. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under different Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were trea

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Liu, Yitao. "Systematic computational methods of unsteady flow simulation based on computational fluid dynamics." Applied and Computational Engineering 12, no. 1 (2023): 151–63. http://dx.doi.org/10.54254/2755-2721/12/20230328.

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Unsteady flow is the dominant flow state in real life; thus, the simulation of it is of vital importance, especially in engineering, for example, the flutter or buffeting of the aerofoil. In the past decades, the progress in computational science greatly paced the development of computational fluid dynamics (CFD), providing powerful tools for simulating unsteady flow via numerical methods. However, the unsteady flow state depends on more variables than a steady flow, including the external conditions in different time moments and the flow's properties that vary with time. The calculation is st

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Zhou, Junwei, Weimin Bao, Yu Li, Li Cheng, and Muxi Bao. "The Modified One-Dimensional Hydrodynamic Model Based on the Extended Chezy Formula." Water 10, no. 12 (2018): 1743. http://dx.doi.org/10.3390/w10121743.

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Although steady uniform friction formulas have been introduced to the framework of a one-dimensional (1D) hydrodynamic model for centuries, the error of friction calculation inevitably undermines the performance of flood routing. Based on successful results of unsteady channel friction research studies, a newly proposed unsteady friction model is introduced to establish a modified 1D hydrodynamic model (namely, the modified SVN model). With the help of a carefully designed parameter calibration method, the performance of the modified SVN model was compared with that of the original SVN model i

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Tian, Chunlai, Tairan Chen, and Tian Zou. "Numerical study of unsteady cavitating flows with RANS and DES models." Modern Physics Letters B 33, no. 20 (2019): 1950228. http://dx.doi.org/10.1142/s0217984919502282.

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Unsteady cavitating flow with high Reynolds number and significant instability commonly exists in fluid machinery and engineering system. The high-resolution approaches, such as direct numerical simulation and large eddy simulation, are not practical for engineering issues due to the significant cost in the computational resource. The objective of this paper is to provide the approach with Detached-Eddy Simulation (DES) model based on the Reynolds-averaged Navier–Stokes (RANS) equations for predicting unsteady cavitating flows. The credibility of the approach is validated by a set of numerical

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Yang, Ming, Shi Ping Zhao, Han Ping Wang, Lin Peng Wang, and Shao Zhu Wang. "Simulation on Torpedo Unsteady Hydrodynamic with the Movement in the Longitudinal Plane." Advanced Materials Research 791-793 (September 2013): 1073–76. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.1073.

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The unsteady hydrodynamic accurate calculation is the premise of submerged body trajectory design and maneuverability design. Calculation model of submerged body unsteady hydrodynamic with the movement in the longitudinal plane was established, which based on unsteady three-dimensional incompressible fluid dynamics theory. Variable speed translational and variable angular velocity of the pitching motion in the longitudinal plane of submerged body was achieved by dynamic mesh method. The unsteady hydrodynamic could be obtained by model under the premise of good quality grid by the results. Mode

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Borg, Matthew K., Duncan A. Lockerby, and Jason M. Reese. "A hybrid molecular–continuum method for unsteady compressible multiscale flows." Journal of Fluid Mechanics 768 (March 10, 2015): 388–414. http://dx.doi.org/10.1017/jfm.2015.83.

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We present an internal-flow multiscale method (‘unsteady-IMM’) for compressible, time-varying/unsteady flow problems in nano-confined high-aspect-ratio geometries. The IMM is a hybrid molecular–continuum method that provides accurate flow predictions at macroscopic scales because local microscopic corrections to the continuum-fluid formulation are generated by spatially and temporally distributed molecular simulations. Exploiting separation in both time and length scales enables orders of magnitude computational savings, far greater than seen in other hybrid methods. We apply the unsteady-IMM

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Li, Wen Bo, Yin Gai Jin, Shuang Yin, and Pei Yan Chen. "Electrical Simulation Experiment and the Analysis of Thermal Conductivity of Materials." Advanced Materials Research 989-994 (July 2014): 599–602. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.599.

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s: Jilin university innovation experiment Electrical Simulation Experiment and the Analysis of Thermal Conductivity of Materials aims to solve the problem of thermocouple measuring tenderness in error. Thermocouple is used to measure temperature when measuring unsteady heat conduction in laboratory. The improved measuring method of unsteady heat conduction puts the breakthrough on the electric simulation method. The text bench is constructed by different shapes of conductive plate which is made of the graphite conductive paint, and voltmeter is refitted by diodes and controlled transformer. Th

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XIA, HAO, and NING QIN. "DETACHED-EDDY SIMULATION FOR SYNTHETIC JETS WITH MOVING BOUNDARIES." Modern Physics Letters B 19, no. 28n29 (2005): 1429–34. http://dx.doi.org/10.1142/s0217984905009584.

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A Detached-Eddy Simulation (DES) with moving boundaries has been developed and applied to synthetic jet flows. Complex unsteady flow patterns of the flows were revealed from the simulation. Comparisons between the simulation and experiments showed reasonably good agreements, which indicates that, as a hybrid RANS/LES method, DES is capable of handling unsteady separations with turbulent boundary layers and time-dependent moving boundary conditions.

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Meakhail, Tarek, and Seung O. Park. "A Study of Impeller-Diffuser-Volute Interaction in a Centrifugal Fan." Journal of Turbomachinery 127, no. 1 (2005): 84–90. http://dx.doi.org/10.1115/1.1812318.

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This paper reports velocity measurement data in the interaction region between the impeller and vaned diffuser and the results of numerical flow simulation of the whole machine (impeller, vaned diffuser and volute) of a single stage centrifugal fan. Two-dimensional instantaneous velocity measurement is done using particle image velocimetry (PIV). Numerical simulation of impeller-diffuser-volute interaction is performed using CFX-Tascflow commercial code. A frozen rotor simulation model is used for the steady calculation and a rotor-stator simulation model is used for the unsteady calculation u

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Li, Tian, Yifan Li, Lai Wei, and Jiye Zhang. "Study on Lateral Vibration of Tail Coach for High-Speed Train under Unsteady Aerodynamic Loads." Vibration 6, no. 4 (2023): 1048–59. http://dx.doi.org/10.3390/vibration6040061.

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As the speed of high-speed trains increases, the vehicle’s lateral stability steadily deteriorates. There have been observations of abnormal vibrations in the tail car, particularly on certain sections of the railway line. This study built a high-speed train aerodynamic simulation model for a three-car consist, and a multibody dynamics simulation model for an eight-car consist based on numerical simulations of train aerodynamics and multibody dynamics. It investigated both steady and unsteady aerodynamic loads, flow field characteristics, and the dynamic performance of vehicles under varied ae

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Liu, Yang, and Zhi Gen Hu. "An Improved Iterative Method of Saturated-Unsaturated Unsteady Seepage Numerical Simulation." Applied Mechanics and Materials 405-408 (September 2013): 363–68. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.363.

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The original iterative method of the saturated-unsaturated unsteady seepage FEM analysis is presented. According to the character of the iterative process, an iterative coefficient is introduced, and a new method is formed. The improved iterative method can enhance and accelerate convergence of the computation efficiently by selecting suitable , and make the saturated-unsaturated unsteady seepage FEM analysis have broader engineering applicability. Three-dimensional FEM analysis program for saturated-unsaturated unsteady seepage is compiled based on the improved algorithm. The algorithm is val

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Martini, P., A. Schulz, H. J. Bauer, and C. F. Whitney. "Detached Eddy Simulation of Film Cooling Performance on the Trailing Edge Cutback of Gas Turbine Airfoils." Journal of Turbomachinery 128, no. 2 (2005): 292–99. http://dx.doi.org/10.1115/1.2137739.

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The present study deals with the unsteady flow simulation of trailing edge film cooling on the pressure side cut back of gas turbine airfoils. Before being ejected tangentially on the inclined cut-back surface, the coolant air passes a partly converging passage that is equipped with turbulators such as pin fins and ribs. The film mixing process on the cut back is complicated. In the near slot region, due to the turbulators and the blunt pressure side lip, turbulence is expected to be anisotropic. Furthermore, unsteady flow phenomena like vortex shedding from the pressure side lip might influen

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Parthiban, V., and Ashwin Russelle. "Turbulence Pattern in Triangular Cylinder." Applied Mechanics and Materials 110-116 (October 2011): 4719–22. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4719.

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In order to predict a turbulent flow around a triangular cylinder a high Reynolds number of 45000 is done in the numerical simulation. In this simulation both steady and unsteady vortex shedding is predicted and various time steps. The numerical method used in this simulation is Reynolds Stress model. For steady and unsteady solution velocity contours and velocity vector plots is to be predicted for the vortex shedding behind the triangular cylinder.

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Liu, Yuwei, Kangkang Li, Xincheng Wang, and Yaofeng Liu. "Numerical simulation of unsteady characteristics of large flow rate jet interference." Journal of Physics: Conference Series 2820, no. 1 (2024): 012071. http://dx.doi.org/10.1088/1742-6596/2820/1/012071.

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Abstract In this paper, for a cone-column-skirt spiral shape, the unsteady characteristics of complex flow caused by strong interference of large flow jets and high-speed incoming flow are studied. The unsteady numerical simulation method based on partition docking structure grid and double time step iteration is used to implement the integrated unsteady calculation of external flow around the aircraft/nozzle flow. The unsteady characteristics of large flow jet interference under the influence of jet startup and shutdown, different jet pressure building forms, and incoming flow conditions (fli

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Fan, S., and B. Lakshminarayana. "Computation and Simulation of Wake-Generated Unsteady Pressure and Boundary Layers in Cascades: Part 1—Description of the Approach and Validation." Journal of Turbomachinery 118, no. 1 (1996): 96–108. http://dx.doi.org/10.1115/1.2836612.

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The unsteady pressure and boundary layers on a turbomachinery blade row arising from periodic wakes due to upstream blade rows are investigated in this paper. A time-accurate Euler solver has been developed using an explicit four-stage Runge–Kutta scheme. Two-dimensional unsteady nonreflecting boundary conditions are used at the inlet and the outlet of the computational domain. The unsteady Euler solver captures the wake propagation and the resulting unsteady pressure field, which is then used as the input for a two-dimensional unsteady boundary layer procedure to predict the unsteady response

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