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arXiv 1502.06575math.APcs.NAmath.NA
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相场方程在Stefan问题奇异极限中的形式

Phase field equation in the singular limit of the Stefan problem

Division of Materials Science, Graduate School of Science and Engineering, Saitama University(埼玉大学理工学研究科材料科学分科)

Jun-ichi Koga, Jiro Koga, Shunji Homma

AI总结:

研究相场方程在Stefan问题奇异极限下的形式,分析相场方程是否能描述相变过程,并探讨界面速度与温度的关系及扩散层宽度的控制方法。

摘要:

相场方程在Stefan问题奇异极限下的形式研究显示,经典Stefan问题可作为相场方程的奇异极限。这些方程描述温度$u$和相场$φ$,包括热方程:$$ u_t+\ellφ_t=Δu, $$ 和Ginzburg-Landau方程:$$ εφ_t=εΔφ-\frac{1}εW^\prime (φ)+\ell (φ)u, $$ 其中$\ell$为潜热,$W$为双井势函数,其井深相等,对应固相和液相。当$ε\to 0$时,一维移动边界速度$v$及圆柱或球体半径速度表现为以下Stefan问题:$$ \left\{ \begin{array}{l} u_t-Δu =0\\\\ \displaystyle v=\frac{1}{2}\left[\frac{\partial u}{\partial n}\right]_Γ\displaystyle u=-\frac{m}{2\ell}[κ-αv]_Γ\end{array} \right. $$ 其中$α$为正参数,$[\frac{\partial u}{\partial n}]_Γ$为$u$的法向导数跃变(从固相到液相),$m=\int_{-1}^1\left(2W(φ)\right)^{1/2}dφ$。由于单组分相变可由相场方程描述,我们分析相场方程,探讨其是否展现Stefan问题。圆柱和球体移动边界速度被确定,方程模拟结果也得以呈现。接着,我们考虑界面速度依赖于温度,通过相场方程参数研究扩散层宽度控制,以实现相场方程的奇异极限。

英文摘要:

The classical Stefan problem is reduced as the singular limit of phase-field equations. These equations are for temperature $u$ and the phase-field $φ$, consists of a heat equation: $$ u_t+\ellφ_t=Δu, $$ and a Ginzburg-Landau equation: $$ εφ_t=εΔφ-\frac{1}εW^\prime (φ)+\ell (φ)u, $$ where $\ell$ is a latent heat and $W$ is a double-well potential whose wells, of equal depth, correspond to the solid and liquid phases. When $ε\to 0$, the velocity of the moving boundary $v$ in one dimension and that of the radius in the cylinder or sphere are shown as the following Stefan problem,\\ $$ \left\{ \begin{array}{l} u_t-Δu =0\\\\ \displaystyle v=\frac{1}{2}\left[\frac{\partial u}{\partial n}\right]_Γ\displaystyle u=-\frac{m}{2\ell}[κ-αv]_Γ\end{array} \right. $$ where $α$ is a positive parameter, $[\frac{\partial u}{\partial n}]_Γ$ is the jump of the normal derivatives of $u$ (from solid to liquid), and $m=\int_{-1}^1\left(2W(φ)\right)^{1/2}dφ$. Since it is sufficient to describe the phase transition of single component by the phase-field equation, we analyze the phase-field equation, and investigate whether the equation shows the Stefan problem or not. The velocity of the moving boundary in the cylinder and sphere are determined and the result of the simulation of the equation is also presented. Next, we consider the velocity of interface which depends on the temperature. The control of width of diffusion layer by the parameter of phase-field equations is investigated in order to realize the singular limit of phase field equations by the numerical method.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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