scholarly journals A mesh-free algorithm for ROF model

2017 ◽  
Vol 2017 (1) ◽  
Author(s):  
Mushtaq Ahmad Khan ◽  
Wen Chen ◽  
Asmat Ullah ◽  
Zhuojia Fu
Keyword(s):  
Author(s):  
Steven J. Lind ◽  
Benedict D. Rogers ◽  
Peter K. Stansby

This paper presents a review of the progress of smoothed particle hydrodynamics (SPH) towards high-order converged simulations. As a mesh-free Lagrangian method suitable for complex flows with interfaces and multiple phases, SPH has developed considerably in the past decade. While original applications were in astrophysics, early engineering applications showed the versatility and robustness of the method without emphasis on accuracy and convergence. The early method was of weakly compressible form resulting in noisy pressures due to spurious pressure waves. This was effectively removed in the incompressible (divergence-free) form which followed; since then the weakly compressible form has been advanced, reducing pressure noise. Now numerical convergence studies are standard. While the method is computationally demanding on conventional processors, it is well suited to parallel processing on massively parallel computing and graphics processing units. Applications are diverse and encompass wave–structure interaction, geophysical flows due to landslides, nuclear sludge flows, welding, gearbox flows and many others. In the state of the art, convergence is typically between the first- and second-order theoretical limits. Recent advances are improving convergence to fourth order (and higher) and these will also be outlined. This can be necessary to resolve multi-scale aspects of turbulent flow.


2021 ◽  
Vol 11 (3) ◽  
pp. 1020
Author(s):  
Mohamadreza Afrasiabi ◽  
Hagen Klippel ◽  
Matthias Roethlin ◽  
Konrad Wegener

Smoothed Particle Hydrodynamics (SPH) is a mesh-free numerical method that can simulate metal cutting problems efficiently. The thermal modeling of such processes with SPH, nevertheless, is not straightforward. The difficulty is rooted in the computationally demanding procedures regarding convergence properties and boundary treatments, both known as SPH Grand Challenges. This paper, therefore, intends to rectify these issues in SPH cutting models by proposing two improvements: (1) Implementing a higher-order Laplacian formulation to solve the heat equation more accurately. (2) Introducing a more realistic thermal boundary condition using a robust surface detection algorithm. We employ the proposed framework to simulate an orthogonal cutting process and validate the numerical results against the available experimental measurements.


2021 ◽  
Vol 186 ◽  
pp. 103266
Author(s):  
Rubens Augusto Amaro ◽  
Andrea Mellado-Cusicahua ◽  
Ahmad Shakibaeinia ◽  
Liang-Yee Cheng
Keyword(s):  

2021 ◽  
Vol 11 (12) ◽  
pp. 5751
Author(s):  
Seyed Ali Mousavi Tayebi ◽  
Saeid Moussavi Tayyebi ◽  
Manuel Pastor

Due to the growing populations in areas at high risk of natural disasters, hazard and risk assessments of landslides have attracted significant attention from researchers worldwide. In order to assess potential risks and design possible countermeasures, it is necessary to have a better understanding of this phenomenon and its mechanism. As a result, the prediction of landslide evolution using continuum dynamic modeling implemented in advanced simulation tools is becoming more important. We analyzed a depth-integrated, two-phase model implemented in two different sets of code to stimulate rapid landslides, such as debris flows and rock avalanches. The first set of code, r.avaflow, represents a GIS-based computational framework and employs the NOC-TVD numerical scheme. The second set of code, GeoFlow-SPH, is based on the mesh-free numerical method of smoothed particle hydrodynamics (SPH) with the capability of describing pore pressure’s evolution along the vertical distribution of flowing mass. Two real cases of an Acheron rock avalanche and Sham Tseng San Tsuen debris flow were used with the best fit values of geotechnical parameters obtained in the prior modeling to investigate the capabilities of the sets of code. Comparison of the results evidenced that both sets of code were capable of properly reproducing the run-out distance, deposition thickness, and deposition shape in the benchmark exercises. However, the values of maximum propagation velocities and thickness were considerably different, suggesting that using more than one set of simulation code allows us to predict more accurately the possible scenarios and design more effective countermeasures.


Author(s):  
Hagen Klippel ◽  
Stefan Süssmaier ◽  
Matthias Röthlin ◽  
Mohamadreza Afrasiabi ◽  
Uygar Pala ◽  
...  

AbstractDiamond wire sawing has been developed to reduce the cutting loss when cutting silicon wafers from ingots. The surface of silicon solar cells must be flawless in order to achieve the highest possible efficiency. However, the surface is damaged during sawing. The extent of the damage depends primarily on the material removal mode. Under certain conditions, the generally brittle material can be machined in ductile mode, whereby considerably fewer cracks occur in the surface than with brittle material removal. In the presented paper, a numerical model is developed in order to support the optimisation of the machining process regarding the transition between ductile and brittle material removal. The simulations are performed with an GPU-accelerated in-house developed code using mesh-free methods which easily handle large deformations while classic methods like FEM would require intensive remeshing. The Johnson-Cook flow stress model is implemented and used to evaluate the applicability of a model for ductile material behaviour in the transition zone between ductile and brittle removal mode. The simulation results are compared with results obtained from single grain scratch experiments using a real, non-idealised grain geometry as present in the diamond wire sawing process.


2002 ◽  
Vol 39 (5) ◽  
pp. 1213-1240 ◽  
Author(s):  
Shaofan Li ◽  
Wing Kam Liu ◽  
Ares J. Rosakis ◽  
Ted Belytschko ◽  
Wei Hao

Geomechanics ◽  
2005 ◽  
Author(s):  
Akira Murakami ◽  
Shin'ichi Arimoto ◽  
Tatsuya Setsuyasu ◽  
Tatsuro Nishiyama

2011 ◽  
Vol 49 (5) ◽  
pp. 649-656 ◽  
Author(s):  
Aidin Jabbari Sahebari ◽  
Yee-Chung Jin ◽  
Ahmad Shakibaeinia

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