Pub Date : 2019-01-01DOI: 10.1016/j.jcpx.2019.100008
C. Hermange , G. Oger , D. Le Touzé
This study aims at improving a coupling strategy between Smoothed Particle Hydrodynamics (SPH) with Finite Element (FE) methods in order to model violent Fluid-Structure Interaction (FSI) problems. An analysis of the SPH-FE coupling from the energetic point of view is carried out. The purpose of this work is to quantify the loss/gain in energy at the fluid-structure interface, within the fluid, and within the structure. Interface energy is especially compared to other energy components, highlighting the importance of this term. Different structure models are considered. Additionally, few proposals are made for improving the quality and efficiency of the coupling strategy. Investigations are performed on 2D simulations of both academic and experimental test cases.
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Pub Date : 2019-01-01DOI: 10.1016/j.jcpx.2019.100018
Paolo Amore , John P. Boyd , Natalia Tene Sandoval
We have applied the finite differences method to the study of a pair of isospectral heterogeneous domains, first introduced in Ref. [1]. We show that Richardson and Padé-Richardson extrapolations can be used (as in the homogeneous case) to obtain very precise approximations to the lowest eigenvalues. We have found that the first few exponents of the asymptotic series for the finite difference eigenvalues are unchanged with from the homogeneous case. Additionally, we have improved the previous best estimates for the case of homogeneous isospectral domains, obtaining 10 extra correct digits for the fundamental mode (and similar results for the other eigenvalues), with respect to the best result previously available.
{"title":"Isospectral heterogeneous domains: A numerical study","authors":"Paolo Amore , John P. Boyd , Natalia Tene Sandoval","doi":"10.1016/j.jcpx.2019.100018","DOIUrl":"https://doi.org/10.1016/j.jcpx.2019.100018","url":null,"abstract":"<div><p>We have applied the finite differences method to the study of a pair of isospectral heterogeneous domains, first introduced in Ref. <span>[1]</span>. We show that Richardson and Padé-Richardson extrapolations can be used (as in the homogeneous case) to obtain very precise approximations to the lowest eigenvalues. We have found that the first few exponents of the asymptotic series for the finite difference eigenvalues are unchanged with from the homogeneous case. Additionally, we have improved the previous best estimates for the case of homogeneous isospectral domains, obtaining 10 extra correct digits for the fundamental mode (and similar results for the other eigenvalues), with respect to the best result previously available.</p></div>","PeriodicalId":37045,"journal":{"name":"Journal of Computational Physics: X","volume":"1 ","pages":"Article 100018"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jcpx.2019.100018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72235988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1016/j.jcpx.2019.100007
Aaron M. Lattanzi , Xiaolong Yin , Christine M. Hrenya
The development of accurate and robust heat transfer correlations for gas–solids flows is integral to the development of efficient multiphase unit operations. Direct numerical simulation (DNS) has been shown to be an effective method for developing such correlations. Specifically, the highly-resolved fields present in DNS may be averaged for use at the macroscopic level. Most commonly, particle-resolved immersed boundary or thermal lattice Boltzmann methods are employed. Here we develop a hybrid DNS framework where the hydrodynamics are resolved by the lattice Boltzmann method and the temperature field by random walk particle tracking (Brownian tracers). The random walk algorithm provides an efficient means for simulating scalar transport and can easily handle complex geometries. However, discontinuous fields pose a significant challenge to the random walk framework – e.g., a particle and fluid with different diffusivities. We derive a technique for handling discontinuities via the diffusivity, arising at a particle–fluid interface, and implement said method within the tracer algorithm. In addition, the heat transfer coefficient in the random walk method is defined and a technique for handling phases with different volumetric heat capacities is also developed. Moreover, the present algorithm is shown to correctly characterize intra-particle temperature gradients present in high Biot number systems. Verification of the code is completed against a host of cases: effective diffusivity of a static gas–solids mixture, hot sphere in unbounded diffusion, cooling sphere in unbounded diffusion, and uniform flow past a hot sphere. Predictions made by the new code are observed to agree with analytical solutions, numerical solutions, empirical correlations, and previous works.
{"title":"A hybrid lattice Boltzmann – random walk method for heat transfer in gas–solids systems","authors":"Aaron M. Lattanzi , Xiaolong Yin , Christine M. Hrenya","doi":"10.1016/j.jcpx.2019.100007","DOIUrl":"https://doi.org/10.1016/j.jcpx.2019.100007","url":null,"abstract":"<div><p>The development of accurate and robust heat transfer correlations for gas–solids flows is integral to the development of efficient multiphase unit operations. Direct numerical simulation (DNS) has been shown to be an effective method for developing such correlations. Specifically, the highly-resolved fields present in DNS may be averaged for use at the macroscopic level. Most commonly, particle-resolved immersed boundary or thermal lattice Boltzmann methods are employed. Here we develop a hybrid DNS framework where the hydrodynamics are resolved by the lattice Boltzmann method and the temperature field by random walk particle tracking (Brownian tracers). The random walk algorithm provides an efficient means for simulating scalar transport and can easily handle complex geometries. However, discontinuous fields pose a significant challenge to the random walk framework – e.g., a particle and fluid with different diffusivities. We derive a technique for handling discontinuities via the diffusivity, arising at a particle–fluid interface, and implement said method within the tracer algorithm. In addition, the heat transfer coefficient in the random walk method is defined and a technique for handling phases with different volumetric heat capacities is also developed. Moreover, the present algorithm is shown to correctly characterize intra-particle temperature gradients present in high Biot number systems. Verification of the code is completed against a host of cases: effective diffusivity of a static gas–solids mixture, hot sphere in unbounded diffusion, cooling sphere in unbounded diffusion, and uniform flow past a hot sphere. Predictions made by the new code are observed to agree with analytical solutions, numerical solutions, empirical correlations, and previous works.</p></div>","PeriodicalId":37045,"journal":{"name":"Journal of Computational Physics: X","volume":"1 ","pages":"Article 100007"},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.jcpx.2019.100007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72236016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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