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research-article

Combined Effect of Thermal Anisotropy and Forced Convection on the Growth of Binary Alloy Equiaxed Dendrites

[+] Author and Article Information
Amamn Jakhar

School of mechanical sciences IIT Bhubaneswar Khurda, Odhisa 752050 India aj13@iitbbs.ac.in

Anirban Bhattacharya

School of Mechanical Sciences, IIT Bhubaneswar Argul, Jatni, Khurda, Odisha Bhubaneswar, Odisha 752050 India anirban@iitbbs.ac.in

Prasenjit Rath

Rourkela Rourkela, 769008 India prasenjit.rath@gmail.com

Swarup Kumar Mahapatra

School of Mechanical Sciences, IIT Bhubaneswar Samantapuri Bhubaneswar, Odisha 751013 India swarup@iitbbs.ac.in

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the Journal of Thermal Science and Engineering Applications. Manuscript received November 14, 2018; final manuscript received January 9, 2019; published online xx xx, xxxx. Assoc. Editor: Dr. Steve Q. Cai.

ASME doi:10.1115/1.4042587 History: Received November 14, 2018; Accepted January 11, 2019

Abstract

A numerical model has been developed to simulate the growth of an equaixed binary alloy dendrite under the combined effect of thermal anisotropy and forced convection. A semi implicit-explicit approach is used where the velocity and pressure fields are solved implicitly using the SIMPLER algorithm, while energy and species conservation equations are treated explicitly. The effect of thermal anisotropy present in the solid crystal is implemented by the addition of a departure source term in the conventional isotropic heat transfer based energy equation. The departure source represents the anisotropic part of the diffusive term in the isotropic heat transfer based energy equation. Simulations were performed to find the relative effect of convection strength and thermal anisotropy on the growth rate and morphology of a dendrite. Subsequently, parametric studies were conducted to investigate the effect of thermal anisotropy ratio, inlet flow velocity, undercooling temperature and relative strength of thermal to mass diffusivity ratio by analyzing the variation of equilibrium tip velocity of the top and left arm, the arm length ratio and the equivalent grain radius. Based on simulations, a chart has been developed which demarcates different regimes in which convection or thermal anisotropy is the most dominant factor influencing the dendrite growth rate. The model has also been extended to study the growth of multiple dendrites with random distribution and orientation. This can be useful for simulation of microstructure evolution under the combined effect of convection and thermal anisotropy.

Copyright © 2019 by ASME
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