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  • Open Access

    ARTICLE

    Modeling a Discontinuous CVD Coating Process: II. Detailed Simulation Results

    Joseph G. Lawrence, John P. Dismukes, Arunan Nadarajah1

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 255-264, 2007, DOI:10.3970/fdmp.2007.003.255

    Abstract The atmospheric chemical vapor deposition process on continuous glass sheets is a well developed one and the parameters that affect it are relatively well understood. When this process is converted to coat discrete glass plates it introduces a new variable, the gap between the glass plates, which can significantly impact the quality of the coatings. In this study a 2D pseudo steady state model of the process was developed to study the effect of the gap, and the ratio of outlet to inlet gas flow rates (called the bias), on the coating quality. The model was solved with the commercially… More >

  • Open Access

    ARTICLE

    Modeling a Discontinuous CVD Coating Process: I. Model Development and Validation

    Joseph G. Lawrence, Arunan Nadarajah1

    FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.3, pp. 247-254, 2007, DOI:10.3970/fdmp.2007.003.247

    Abstract A simplified 2D pseudo steady state model was developed for an atmospheric chemical vapor deposition (CVD) process on glass. This is used to study the feasibility of converting a continuous coating process to one with discrete glass plates with a gap between them. A preliminary estimate employing mass transfer correlations suggested that there would be significant concentration variations due to the gap between the plates. More detailed studies were done by solving the model numerically employing a finite difference scheme with a vorticity-stream function formulation, and employing the commercial computational fluid dynamics program FIDAP which employs a finite element scheme.… More >

  • Open Access

    ARTICLE

    Coalescence and Non-coalescence Phenomena in Multi-material Problems and Dispersed Multiphase Flows: Part 2, A Critical Review of CFD Approaches

    Marcello Lappa1

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 213-234, 2005, DOI:10.3970/fdmp.2005.001.213

    Abstract The physical properties of many emulsions and metal alloys strongly depend on the multiphase morphology which is controlled to a great degree by particle-particle interaction during the related processing. In the present article significant effort is devoted to illustrate the philosophy of modeling for these phenomena and some insights into the physics. Within such a context working numerical techniques that have enjoyed a widespread use over recent years are presented and/or reviewed. Finally a focused and critical comparison of these possible approaches is reported illustrating advantages and disadvantages, strengths and weaknesses, past history and future directions. More >

  • Open Access

    ARTICLE

    Coalescence and Non-coalescence Phenomena in Multi-material Problems and Dispersed Multiphase Flows: Part 1, A Critical Review of Theories

    Marcello Lappa1

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 201-212, 2005, DOI:10.3970/fdmp.2005.001.201

    Abstract The manuscript deals with a presentation of the most reliable theories introduced over the years to model particle coalescence and non-coalescence phenomena at both macroscopic and microscopic length scales (including historical developments and very recent contributions) and moves through other macrophysical mechanisms that can cause spatial separation of the fluid phases (liquid-liquid or liquid-gas) in multi-material problems, while providing a rigorous theoretical framework for deeper understanding of how drop (or bubble) migration due to gravity and/or Marangoni effects can interact cooperatively with coalescence to significantly affect the multiphase pattern formation, its evolutionary progress as well as the final quality of… More >

  • Open Access

    ARTICLE

    Structural Evolutions of the Clusters During the Melting and Coalescence Processes

    Kai Wang1, Guojian Li1, Qiang Wang1,2, Huimin Wang1, Jiaojiao Du1, Jicheng He1

    CMC-Computers, Materials & Continua, Vol.38, No.2, pp. 79-89, 2013, DOI:10.3970/cmc.2013.038.079

    Abstract Study on the behaviors of the melting and coalescence of clusters in atomic scale may create new structure at nanoscale, which is a very important research field. The structural evolutions of clusters Cu321, Co321, and Ni321 during their melting and coalescence processes were studied using molecular dynamics simulation with a general embedded atom method in this paper. It was found that the geometries of Cu321 and Co321 transformed to icosahedron from fcc near their melting points, which leads to the increase of their melting points. Concerning the coalescence, it was found that Cu atoms easily formed a coating layer on… More >

  • Open Access

    ARTICLE

    Joint Bearing Mechanism of Coal Pillar and Backfilling Body in Roadway Backfilling Mining Technology

    Zhengzheng Cao1, Ping Xu1,*, Zhenhua Li2, Minxia Zhang1, Yu Zhao1, Wenlong Shen2

    CMC-Computers, Materials & Continua, Vol.54, No.2, pp. 137-159, 2018, DOI:10.3970/cmc.2018.054.137

    Abstract In the traditional mining technology, the coal resources trapped beneath surface buildings, railways, and water bodies cannot be mined massively, thereby causing the lower coal recovery and dynamic disasters. In order to solve the aforementioned problems, the roadway backfilling mining technology is developed and the joint bearing mechanism of coal pillar and backfilling body is presented in this paper. The mechanical model of bearing system of coal pillar and backfilling body is established, by analyzing the basic characteristics of overlying strata deformation in roadway backfilling mining technology. According to the Ritz method in energy variation principle, the elastic solution expression… More >

  • Open Access

    ARTICLE

    Seepage-Stress-Damage Coupled Model of Coal Under Geo-Stress Influence

    Yi Xue1,2,3, Faning Dang2, Rongjian Li2, Liuming Fan2, Qin Hao4, Lin Mu2, Yuanyuan Xia2

    CMC-Computers, Materials & Continua, Vol.54, No.1, pp. 43-59, 2018, DOI:10.3970/cmc.2018.054.043

    Abstract In the seepage-stress-damage coupled process, the mechanical properties and seepage characteristics of coal are distinctly different between pre-peak stage and post-peak stage. This difference is mainly caused by damage of coal. Therefore, in the process of seepage and stress analysis of coal under the influence of excavation or mining, we need to consider the weakening of mechanical properties and the development of fractures of damaged coal. Based on this understanding, this paper analyzes the influence of damage on mechanics and seepage behavior of coal. A coupled model is established to analyze the seepage-stress-damage coupled process of coal. This model implemented… More >

  • Open Access

    ARTICLE

    Research on damage distribution and permeability distribution of coal seam with slotted borehole

    Yi Xue1,2, Feng Gao1,2,3, Xingguang Liu4, Xiru Li2

    CMC-Computers, Materials & Continua, Vol.47, No.2, pp. 127-141, 2015, DOI:10.3970/cmc.2015.047.127

    Abstract In order to study the effect of high pressure water jet cutting technology on the permeability of single coal seam, we use the damage variable to describe the fracture distribution of coal seam, develop the 3-D finite element program based on the damage theory, and then analyze the damage distribution of coal seam after drilling and slotting. Using MTS815 rock mechanics testing system and the permeability test system, we conduct the permeability test and get the relationship between permeability and damage. Based on the damage distribution of coal seam after drilling and slotting and the permeability change law, we analyze… More >

  • Open Access

    ARTICLE

    Effect of Interface Energy on Size-Dependent Effective Dynamic Properties of Nanocomposites with Coated Nano-Fibers

    Xue-Qian Fang1,2, Ming-Juan Huang1, Jun-Ying Wu3, Guo-Quan Nie1, Jin-Xi Liu1

    CMC-Computers, Materials & Continua, Vol.33, No.2, pp. 199-211, 2013, DOI:10.3970/cmc.2013.033.199

    Abstract In nanocomposites, coated nano-fibers are often used to obtain good performance, and the high interface-to-volume ratio shows great effect on the macroscopic effective properties of nanocomposites. In this study, the effect of interface energy around the unidirectional coated nanofibers on the effective dynamic effective properties is explicitly addressed by effective medium method and wave function expansion method. The multiple scattering resulting from the series coating nano-fibers is reduced to the problem of one typical nano-fiber in the effective medium. The dynamic effective shear modulus is obtained on the basis of the derived imperfect interface conditions. Analyses show that the effect… More >

  • Open Access

    ARTICLE

    Effects of TGO Roughness on Indentation Response of Thermal Barrier Coatings

    Taotao Hu1, gping Shen1,2

    CMC-Computers, Materials & Continua, Vol.17, No.1, pp. 41-58, 2010, DOI:10.3970/cmc.2010.017.041

    Abstract In this paper, an axisymmetric indentation model is set up to calculate the effects of the roughness of the thermally grown oxide (TGO) layer, which was modeled as a sinusoidal wave, on the indentation response of the thermal barrier coatings. It is found that the amplitude, wavelength, and thickness of the thermally grown oxide layer have obvious influences on the indentation response, while the effect of the indenter position can be neglected. In the top coating layer, residual stress mainly occurs below the indenter and around the nearest two peaks of the thermally grown oxide layer to the indenter. Only… More >

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