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A lattice Boltzmann–cellular automaton study on dendrite growth with melt convection in solidification of ternary alloys 下载免费PDF全文
A lattice Boltzmann(LB)–cellular automaton(CA) model is employed to study the dendrite growth of Al-4.0 wt%Cu–1.0 wt%Mg alloy. The effects of melt convection, solute diffusion, interface curvature, and preferred growth orientation are incorporated into the coupled model by coupling the LB–CA model and the CALPHAD-based phase equilibrium solver,Pan Engine. The dendrite growth with single and multiple initial seeds was numerically studied under the conditions of pure diffusion and melt convection. Effects of initial seed number and melt convection strength were characterized by newdefined solidification and concentration entropies. The numerical result shows that the growth behavior of dendrites, the final microstructure, and the micro-segregation are significantly influenced by melt convection during solidification of the ternary alloys. The proposed solidification and concentration entropies are useful characteristics bridging the solidification behavior and the microstructure evolution of alloys. 相似文献
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A new numerical method named as basic function method is proposed. It can directly discretize differential operators on unstructured grids. By expanding the basic function to approach the exact function, the central and upwind schemes of derivative are constructed. By using the second-order polynomial as a basic function and applying the flux splitting method and the combination of central and upwind schemes to suppress non-physical fluctuation near shock waves, a second-order basic function scheme of polynomial type is proposed to solve inviscid compressible flows numerically. Numerical results of typical examples for two-dimensional inviscid compressible transonic and supersonic steady flows indicate that the new scheme has high accuracy and high resolution for shock waves. Combined with the adaptive remeshing technique, satisfactory results can be obtained. 相似文献
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为了测量高一学生在应用化学键概念时元认知的参与程度,设计了基于元认知理论的化学键概念应用问卷。该问卷包括共价键和离子键2个基本概念,每个基本概念包括5道封闭式题目。在每道封闭式题目之后追加2个开放式任务,用于测量学生应用化学键概念时元认知知识和元认知监控的参与程度。对已经学过化学键概念的高一学生进行测试后的调查数据分析表明,该问卷具有较高的内部一致性,并具有较好的信度和效度指标。因此,该问卷可作为一种测量学生应用化学键概念时元认知参与程度的工具,并具有较强的应用价值。 相似文献
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