Sintering of two particles by surface and grain boundary diffusion – a three-dimensional model and a numerical study

1998 ◽  
Vol 12 (2) ◽  
pp. 84-104 ◽  
Author(s):  
Wen Zhang ◽  
Ian Gladwell
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Numerical Study ◽  
Three Dimensional ◽  
Grain Boundary Diffusion ◽  
Dimensional Model ◽  
Three Dimensional Model

On the numerical study of thermohydrodynamics and biochemistry of inland water bodies

2021 ◽  
Author(s):  
Daria Gladskikh ◽  
Evgeny Mortikov ◽  
Victor Stepanenko
Keyword(s):  
Mixed Layer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Water Bodies ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
Lake Model ◽  
Upper Mixed Layer ◽  
The One

<p>The study of thermodynamic and biochemical processes of inland water objects using one- and three-dimensional RANS numerical models was carried out both for idealized water bodies and using measurements data. The need to take into account seiche oscillations to correctly reproduce the deepening of the upper mixed layer in one-dimensional (vertical) models is demonstrated. We considered the one-dimensional LAKE model [1] and the three-dimensional model [2, 3, 4] developed at the Research Computing Center of Moscow State University on the basis of a hydrodynamic code combining DNS/LES/RANS approaches for calculating geophysical turbulent flows. The three-dimensional model was supplemented by the equations for calculating biochemical substances by analogy with the one-dimensional biochemistry equations used in the LAKE model. The effect of mixing processes on the distribution of concentration of greenhouse gases, in particular, methane and oxygen, was studied.</p><p>The work was supported by grants of the RF President’s Grant for Young Scientists (MK-1867.2020.5, MD-1850.2020.5) and by the RFBR (19-05-00249, 20-05-00776). </p><p>1. Stepanenko V., Mammarella I., Ojala A., Miettinen H., Lykosov V., Timo V. LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes // Geoscientific Model Development. 2016. V. 9(5). P. 1977–2006.<br>2. Mortikov E.V., Glazunov A.V., Lykosov V.N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure-strain correlations // Russian Journal of Numerical Analysis and Mathematical Modelling. 2019. 34(2). P. 119-132.<br>3. Mortikov, E.V. Numerical simulation of the motion of an ice keel in stratified flow // Izv. Atmos. Ocean. Phys. 2016. V. 52. P. 108-115.<br>4. Gladskikh D.S., Stepanenko V.M., Mortikov E.V. On the influence of the horizontal dimensions of inland waters on the thickness of the upper mixed layer // Water Resourses. 2021.V. 45, 9 pages. (in press) </p>

Numerical Study of Grain Boundary Diffusion in Nanocrystalline Materials

2005 ◽  
Vol 237-240 ◽  
pp. 1043-1048 ◽  
Author(s):  
D. Gryaznov ◽  
J. Fleig ◽  
Joachim Maier
Keyword(s):  
Grain Boundary ◽  
Nanocrystalline Materials ◽  
Boundary Diffusion ◽  
Nanocrystalline Material ◽  
Numerical Study ◽  
Average Length ◽  
Type A ◽  
Grain Boundary Diffusion ◽  
Conventional Models ◽  
Diffusion Profiles

Diffusion in nanocrystalline materials is becoming an increasingly important topic. The analysis of diffusion profiles obtained in nanocrystalline materials with enhanced grain boundary diffusion, however, is not straightforward since assumptions made in the deviation of the conventional models are often not fulfilled. In this contribution numerical diffusion studies are performed in order to investigate effects caused by the high density of interfaces in nanocrystalline material. A continuum model based on the 2D 2-nd Fick’s law was solved by means of the finite element method. This allows us to analyze diffusion profiles for different geometrical situations such as a single boundary, square grains with the grain size of 80 nm and 25 nm and geometries comprising differently oriented boundaries of the average length of 30 nm . The analysis was carried out for different diffusion lengths corresponding to Harrison type A and type B kinetic regimes. For the isolated boundary a very good agreement was achieved in comparison with the classical Whipple’s solution. For nanocrystalline material, however, considerable errors can occur when analyzing the averaged diffusion profiles in the conventional Harrison type A and B kinetics.

On the modeling of thermohydrodynamic and biogeochemical processes in the inland water objects

2020 ◽  
Author(s):  
Daria Gladskikh ◽  
Evgeny Mortikov ◽  
Victor Stepanenko
Keyword(s):  
Carbon Dioxide ◽  
Numerical Study ◽  
Three Dimensional ◽  
Measurement Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Inland Water ◽  
One Dimensional ◽  
Biochemical Processes ◽  
Dimensional Models

<p>Currently, one-dimensional and three-dimensional models are widely used to model thermohydrodynamic and biochemical processes in lakes and water rеreservoirs. One-dimensional models are highly computationally efficient and are used to parameterize land water bodies in climate models, however, when calculating large lakes and reservoirs with complex geometry, such models may incorrectly reproduce processes associated with horizontal heterogeneity. This becomes especially important for the prediction of water quality and euthrophication.</p><p>A three-dimensional model of thermohydrodynamics and biochemistry of an inland water obect is presented, which is based on the hydrostatic RANS model [1-3], and the parameterization of biochemical processes is implemented by analogy with the scheme for calculating biochemistry in the one-dimensional LAKE model [4]. Thus, the three-dimensional model is supplemented by a description of the transport of substances such as oxygen (O<sub>2</sub>), carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), as well as phyto- and zooplankton. The effect of turbulent diffusion and large-scale water movements on the distribution of a methane concentration field is studied.</p><p>To verify the calculation results, idealized numerical experiments and comparison with the measurement data on Lake Kuivajärvi (Finland) were used.</p><p>The work was supported by grants of the RF President’s Grant for Young Scientists (MK-1867.2020.5, MD-1850.2020.5) and by the RFBR (18-05-00292, 18-35-00602, 20-05-00776). <br><br>References:<br>[1] Mortikov E.V. Numerical simulation of the motion of an ice keel in stratified flow // Izv. Atmos. Ocean. Phys. 2016. 52. P. 108-115.<br>[2] Mortikov E.V., Glazunov A.V., Lykosov V.N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure-strain correlations // Russian Journal of Numerical Analysis and Mathematical Modelling. 2019. V. 34, N 2. P. 119-132.<br>[3] D.S. Gladskikh, V.M. Stepanenko, E.V. Mortikov, On the influence of the horizontal dimensions of inland waters on the thickness of the upper mixed layer. // Water Resourses. 2019. 18 pages. (submitted)<br>[4] Victor Stepanenko, Ivan Mammarella, Anne Ojala, Heli Miettinen, Vasily Lykosov, and Vesala Timo. LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes. Geoscientific Model Development, 9(5): 1977–2006, 2016.</p>

Numerical Study of the Pusher-Type Billet Reheating Furnace

2005 ◽  
Author(s):  
Linjiang Zou ◽  
Chaoxiang Li ◽  
Yinmei Yuan ◽  
Wei Guo ◽  
Fan Yang ◽  
...  
Keyword(s):  
Software Package ◽  
High Speed ◽  
Gas Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cfd Model ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Iron And Steel ◽  
Reheating Furnace

In the present work, a commercial CFD software package, FLUENT, was used to develop a three-dimensional model of pusher-type billet reheating furnace for the second high speed wire rod plant of XiangTan Iron and steel Co. Ltd. The purpose of the study was to gain a better understanding of the gas flow and velocity and pressure distribution in the furnace. The results show that the numerical results are in agreement with the practice and the characteristics of the furnace configuration. The CFD model can be used to improve the performance and structure by analyzing and studying the behavior of the reheating furnace.

Drying of solids with irregular geometry: numerical study and application using a three-dimensional model

2013 ◽  
Vol 49 (5) ◽  
pp. 695-709 ◽  
Author(s):  
Vera S. O. Farias ◽  
Wilton Pereira Silva ◽  
Cleide M. D. P. S. e Silva ◽  
Vicente P. T. Rocha ◽  
Antonio G. B. Lima
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Irregular Geometry

scholarly journals Finite element analysis for airfield asphalt pavements rutting prediction

2015 ◽  
Vol 63 (2) ◽  
pp. 397-403 ◽  
Author(s):  
G. Leonardi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Permanent Deformation ◽  
Three Dimensional ◽  
Flexible Pavement ◽  
Asphalt Pavements ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
The Impact

Abstract This paper presents a numerical study of an aircraft wheel impacting on a flexible pavement. The proposed three dimensional model simulates the behaviour of flexible runway pavement during the landing phase. This model was implemented in a finite element code in order to investigate the impact of repeated cycles of loads on pavement permanent deformation. In the model a traditional multi-layer pavement structure was considered. In addition, the asphalt layer (HMA) was assumed to follow an elasto-viscoplastic behaviour. The results demonstrate the capability of the model in predicting the permanent deformation distribution in the asphalt layer

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