Numerical Simulation of the Austenitizing Process in Hypoeutectoid Fe-C Steels

2014 ◽  
Author(s):  
Dehao Liu ◽  
Gang Wang ◽  
Zhenguo Nie ◽  
Yiming (Kevin) Rong
Keyword(s):  
Front Tracking ◽  
Two Dimensional ◽  
Austenite Matrix ◽  
Transformation Kinetics ◽  
Special Volume ◽  
Dimensional Model ◽  
Austenitization Temperature ◽  
One Dimensional ◽  
Two Dimensional Model ◽  
2D Model

For predicting of diffusive phase transformations during the austenitizing process in hypoeutectoid Fe-C steels, a two-dimensional model has been developed. The diffusion equations are solved within each phase (α and γ) using an explicit finite volume technique formulated using a square grid. The discrete α/γ interface is represented by special volume elements α/γ. The result showing the dissolution of ferrite particles in the austenite matrix are presented at different stages of the phase transformation. Specifically, the influence of the microstructure scale and heating rate on the transformation kinetics has been investigated. Final austenitization temperature calculated with this 2D model is compared with predictions of a simpler one dimensional (1D) front-tracking calculation.

scholarly journals Detecting isolation by distance using phylogenies of genes.

Genetics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 249-260 ◽  
Author(s):  
M Slatkin ◽  
W P Maddison
Keyword(s):  
Migration Rate ◽  
Regression Coefficient ◽  
Isolation By Distance ◽  
Alternative Methods ◽  
Simple Relationship ◽  
Two Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Structured Population ◽  
Two Dimensional Model

Abstract We introduce a method for analyzing phylogenies of genes sampled from a geographically structured population. A parsimony method can be used to compute s, the minimum number of migration events between pairs of populations sampled, and the value of s can be used to estimate the effective migration rate M, the value of Nm in an island model with local populations of size N and a migration rate m that would yield the same value of s. Extensive simulations show that there is a simple relationship between M and the geographic distance between pairs of samples in one- and two-dimensional models of isolation by distance. Both stepping-stone and lattice models were simulated. If two demes k steps apart are sampled, then, s, the average value of s, is a function only of k/(Nm) in a one-dimensional model and is a function only of k/(Nm)2 in a two-dimensional model. Furthermore, log(M) is approximately a linear function of log(k). In a one-dimensional model, the regression coefficient is approximately -1 and in a two-dimensional model the regression coefficient is approximately -0.5. Using data from several locations, the regression of log(M) on log(distance) may indicate whether there is isolation by distance in a population at equilibrium and may allow an estimate of the effective migration rate between adjacent sampling locations. Alternative methods for analyzing DNA sequence data from a geographically structured population are discussed. An application of our method to the data of R. L. Cann, M. Stoneking and A. C. Wilson on human mitochondrial DNA is presented.

A Two-Dimensional Model of the Fluid Dynamics of an Air Reverser

1998 ◽  
Vol 65 (1) ◽  
pp. 171-177 ◽  
Author(s):  
S. Mu¨ftu¨ ◽  
T. S. Lewis ◽  
K. A. Cole ◽  
R. C. Benson
Keyword(s):  
Design Guidelines ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Web Handling ◽  
One Dimensional ◽  
Air Supply ◽  
Two Dimensional Model ◽  
The One ◽  
The Web

A theoretical analysis of the fluid mechanics of the air cushion of the air reversers used in web-handling systems is presented. A two-dimensional model of the air flow is derived by averaging the equations of conservation of mass and momentum over the clearance between the web and the reverser. The resulting equations are Euler’s equations with nonlinear source terms representing the air supply holes in the surface of the reverser. The equations are solved analytically for the one-dimensional case and numerically for the two-dimensional case. Results are compared with an empirical formula and the one-dimensional airjet theory developed for hovercraft. Conditions that maximize the air pressure supporting the web are analyzed and design guidelines are deduced.

scholarly journals 2D Model of Transfer Processes for Water Boiling Flow in Microchannel

2021 ◽  
Vol 5 (3) ◽  
pp. 42
Author(s):  
Valery A. Danilov ◽  
Christian Hofmann ◽  
Gunther Kolb
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Temperature Profiles ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Transfer Processes ◽  
Two Dimensional Model ◽  
Boiling Flow ◽  
Homogeneous Mixture Model ◽  
2D Model

The modeling of transfer processes is a step in the generalization and interpretation of experimental data on heat transfer. The developed two-dimensional model is based on a homogeneous mixture model for boiling water flow in a microchannel with a new evaporation submodel. The outcome of the simulation is the distribution of velocity, void fraction and temperature profiles in the microchannel. The predicted temperature profile is consistent with the experimental literature data.

Modeling Flash Diffusivity Experiments in Two Dimensions for Thick Samples

2008 ◽  
Author(s):  
Robert L. McMasters
Keyword(s):  
Experimental Data ◽  
Laser Flash ◽  
Two Dimensions ◽  
Flash Method ◽  
Two Dimensional ◽  
Dimensional Model ◽  
One Dimensional ◽  
Two Dimensional Model ◽  
Dimensional Analysis Method ◽  
Flash Diffusivity

The laser flash method for measuring thermal diffusivity is well established and has been in use for many years. Early analysis methods employed a simple model, in which one dimensional transient conduction was assumed, with insulated surfaces during the time subsequent to the flash. More recently, models of grater sophistication have been applied to flash diffusivity experiments. These models have been matched to experimental data using nonlinear regression and assume one-dimensional conduction. The advanced models have achieved highly accurate agreement with experimental data taken from thin samples, on the order of one millimeter in thickness. As samples become thicker, models which neglect edge losses can lose some conformity to the experimental data. The present research involves the application of a two dimensional model which allows for penetration of the laser flash into the sample. The accommodation of the flash penetration is important for porous materials, where the coarseness of the porosity is more than one percent of the sample thickness. Variability of the area of incidence of the flash is also investigated to determine the effect on the model and the results. Statistical methods are used in order to make a determination as to the validity of the two dimensional model, as compared with the one dimensional analysis method.

scholarly journals Floodplain Zoning Simulation by Using HEC-RAS and CCHE2D Models in the Sungai Maka River

2016 ◽  
Vol 9 ◽  
pp. ASWR.S36089 ◽  
Author(s):  
Ahmad ShahiriParsa ◽  
Mohammad Noori ◽  
Mohammad Heydari ◽  
Mahmood Rashidi
Keyword(s):  
Flood Damage ◽  
Complex Behavior ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Efficient Tool ◽  
Cross Sectional ◽  
One Dimensional ◽  
River Flooding ◽  
Two Dimensional Model ◽  
Analysis System

River flooding causes several human and financial casualties. It is necessary to perform research studies and implement subsequent actions consistent with the nature of the river. In order to reduce flood damage, floodplain zoning maps and river cross-sectional boundaries are important to nonstructural measures in planning and optimizing utilization of the areas around the river. Due to the complex behavior of the rivers during floods, computer modeling is the most efficient tool with the least possible cost to study and simulate the behavior of the rivers. In this study, one-dimensional model Hydrologic Engineering Centers–-River Analysis System and two-dimensional model CCHE2D were used to simulate the flood zoning in the Sungai Maka district in Kelantan state, Malaysia. The results of these two models in most sections approximately match. Most differences in the results were in the shape of the river.

scholarly journals A NUMERICAL MODEL OF THE ST. LAWRENCE RIVER

1972 ◽  
Vol 1 (13) ◽  
pp. 127
Author(s):  
David Prandle
Keyword(s):  
Numerical Model ◽  
Flow Distribution ◽  
Flow Visualisation ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Simple Method ◽  
One Dimensional ◽  
Two Dimensional Model ◽  
The One ◽  
St Lawrence River

A one-dimensional numerical model of a 340 mile section of the St. Lawrence River has been formulated to study tidal propagation. For a more detailed study of the flow distribution in a localised section of the river a two-dimensional model was used. A half mile square grid was used to schematise an area of approximately 20 miles long by 15 miles wide. This two-dimensional model was embodied within the one-dimensional model to permit a free interaction of flow across the boundaries. For the one-dimensional case, a comparison of model and prototype results is included for both elevation and velocity. For the two-dimensional model a comparison of flow distribution was made by using field results obtained from photographing ice movement and from drogue movement. To interpret the results of the two-dimensional model into a simple method of flow visualisation, use was made of animation techniques. A movie film was made that demonstrates both tidal rise and fall and the associated horizontal velocities. Elevation was reproduced by use of varying shades of coloured paper to simulate contours, velocities were represented by simulating drogue movement to produce smoke streaks.

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