Efficient parallel implementation of incompressible pipe flow algorithm based on SIMPLE

Zhang, Jilin; Yuan, Junfeng; Wan, Jian; Mei, Jie; Zhu, Li-Ting; Zhou, L.; Jiang, Congfeng; Peng, Di; Wang, Jue

doi:10.1002/cpe.3000

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…RNG -turbulence model is used in the steady computation. SIMPLE algorithm is used in coupling between pressures and velocities [25][26][27][28]. Standard wall face function is used for the near wall face.…”

Section: Computational Model Of Pantographs and Experimental Verificamentioning

confidence: 99%

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Sun

Han

2018

Complexity

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Pantographs are important devices on high-speed trains. When a train runs at a high speed, concave and convex parts of the train cause serious airflow disturbances and result in flow separation, eddy shedding, and breakdown. A strong fluctuation pressure field will be caused and transformed into aerodynamic noises. When high-speed trains reach 300 km/h, aerodynamic noises become the main noise source. Aerodynamic noises of pantographs occupy a large proportion in far-field aerodynamic noises of the whole train. Therefore, the problem of aerodynamic noises for pantographs is outstanding among many aerodynamics problems. This paper applies Detached Eddy Simulation (DES) to conducting numerical simulations of flow fields around pantographs of highspeed trains which run in the open air. Time-domain characteristics, frequency-domain characteristics, and unsteady flow fields of aerodynamic noises for pantographs are obtained. The acoustic boundary element method is used to study noise radiation characteristics of pantographs. Results indicate that eddies with different rotation directions and different scales are in regions such as pantograph heads, hinge joints, bottom frames, and insulators, while larger eddies are on pantograph heads and bottom frames. These eddies affect fluctuation pressures of pantographs to form aerodynamic noise sources. Slide plates, pantograph heads, balance rods, insulators, bottom frames, and push rods are the main aerodynamic noise source of pantographs. Radiated energies of pantographs are mainly in mid-frequency and high-frequency bands. In high-frequency bands, the far-field aerodynamic noise of pantographs is mainly contributed by the pantograph head. Single-frequency noises are in the far-field aerodynamic noise of pantographs, where main frequencies are 293 Hz, 586 Hz, 880 Hz, and 1173 Hz. The farther the observed point is from the noise source, the faster the sound pressure attenuation will be. When the distance of two adjacent observed points is increased by double, the attenuation amplitude of sound pressure levels for pantographs is around 6.6 dB.

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Section: Computational Model Of Pantographs and Experimental Verificamentioning

confidence: 99%

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Sun

Han

2018

Complexity

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“…Using graphical processors to speed up computations of 3D finite difference algorithms is a problem that has recently been well addressed in many articles [14][15][16][17][18][19]. Methods described in the previous sections fall within complex 3D stencil computations.…”

Section: Related Workmentioning

confidence: 99%

Optimizing the computation of a parallel 3D finite difference algorithm for graphics processing units

Porter-Sobieraj

Cygert²,

Kikoła

et al. 2014

Concurrency and Computation

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This paper explores the possibilities of using a graphics processing unit for complex 3D finite difference computation via MUSTA-FORCE and WENO algorithms. We propose a novel algorithm based on the new properties of CUDA surface memory optimized for 2D spatial locality and compare it with 3D stencil computations carried out via shared memory, which is currently considered to be the best approach. A case study was performed for the extensive generation of a time series of 3D grids of arbitrary size used in the computation of collisions between heavy nuclei in terms of relativistic hydrodynamics. It proved that implementation based on surface memory is as much as 23% faster than an equivalent implementation using shared memory. 4 4 1592 J. PORTER-SOBIERAJ ET AL.heavy ion collisions create a highly dynamic system, hydrodynamic models can be used to describe an intermediate stage in the collisions, where the assumption is valid [1].Hydrodynamic simulations of heavy ion collisions include three major components:1. Initial conditions for the simulations; 2. Hydrodynamic evolution of the system; 3. Freeze-out, where a hydrodynamic picture is no longer valid and particles have to be treated as individual entities.At the beginning, nuclear matter is in the pre-equilibrium stage, and a hydro approach can be only used when the system reaches the local thermal equilibrium. For the initial conditions, another model has to be used. The Glauber model [2] is often used for this purpose, although there are other choices available. Freeze-out is another stage where a hydro-like description is not valid because the distance between particles no longer allows for treating them as a continuous medium. For this stage, a transport theory is more appropriate. Freeze-out usually occurs as a sudden freeze-out, where a particle decouples from a bulk when the energy density is below a certain threshold. Then, after the hydro stage, further propagation of particles is simulated using a transport model, UrQMD [3] for instance.To exploit the full potential of realistic hydrodynamics, fully (3 + 1)-dimensional simulations (the three spatial dimensions + time) are necessary to study the system's evolution without any assumptions regarding its symmetries. It is a compelling idea; however, such simulations are extremely expensive in terms of computing power. Initial conditions for the hydro models are also important. The fluctuations in the pre-equilibrium stage phase might have an impact on the dynamics of the nuclear medium; therefore, event-by-event studies (where an event is a single collision between heavy ions) with fluctuating initial conditions and with a large amount of statistics are of particular interest and require a fast and efficient computer code. Another important topic, from the physics perspective, is studies of jets. Jets are narrow beams of particles with a high momentum, and their propagation through the hot nuclear medium can provide information about the fundamental properties of the Quark-Gluon Plasma (transport coefficien...

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“…Many scholars have proposed different methods for nucleus segmentation based on the ISBI2014 and ISBI2015 public datasets. The algorithms for nucleus segmentation are mainly divided into simple linear iterative clustering (SLIC) method [5][6][7][8], region-based segmentation method [7,[9][10][11][12][13], convolutional neural network (CNN) [14][15][16][17], and clustering method [18][19][20][21][22][23][24][25][26][27][28]. SLIC superpixel algorithm is one of the most popular nucleus segmentation methods currently.…”

Section: Introductionmentioning

confidence: 99%

Nucleus segmentation of cervical cytology images based on multi-scale fuzzy clustering algorithm

et al. 2020

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In the screening of cervical cancer cells, accurate identification and segmentation of nucleus in cell images is a key part in the early diagnosis of cervical cancer. Overlapping, uneven staining, poor contrast, and other reasons present challenges to cervical nucleus segmentation. We propose a segmentation method for cervical nuclei based on a multi-scale fuzzy clustering algorithm, which segments cervical cell clump images at different scales. We adopt a novel interesting degree based on area prior to measure the interesting degree of the node. The application of these two methods not only solves the problem of selecting the categories number of the clustering algorithm but also greatly improves the nucleus recognition performance. The method is evaluated by the IBSI2014 and IBSI2015 public datasets. Experiments show that the proposed algorithm has greater advantages than the state-of-the-art cervical nucleus segmentation algorithms and accomplishes high accuracy nucleus segmentation results. ARTICLE HISTORY

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Efficient parallel implementation of incompressible pipe flow algorithm based on SIMPLE

Cited by 6 publications

References 18 publications

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Numerical Modeling and Investigation on Aerodynamic Noise Characteristics of Pantographs in High‐Speed Trains

Optimizing the computation of a parallel 3D finite difference algorithm for graphics processing units

Nucleus segmentation of cervical cytology images based on multi-scale fuzzy clustering algorithm

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