李贝贝
,
孙文科
,
吕浩
,
肖瑞雪
,
徐洪涛
,
杨茉
工程热物理学报
本文利用计算流体力学CFD技术,对内置发热圆的方腔内双扩散混合对流的振荡特性进行了数值模拟研究.发热圆为高温高浓度且位于方腔中心,低温低浓度的流体从方腔左侧底部流进,右侧顶部流出.在不同的理查德数m(0.001≤Ri≤1.0)和发热圆直径和方腔边长的比值S(0.2≤S≤0.6)下,利用时间历程和相空间轨迹法来量化分析方腔内部的振荡特性.研究结果表明:当Ri=0.001时,在S=0.6的情况下,方腔内双扩散混合对流呈现出周期性振荡状态;在S=0.2和0.4的情况下,方腔内双扩散混合对流呈现出非周期性振荡状态.而当Ri≥0.005时,无论S为多大,方腔内双扩散混合对流均呈现出稳定流动状态.
关键词:
方腔
,
双扩散混合对流
,
振荡
,
数值模拟
Junming LIU Zhiguo LIU Zhuangchun WU National Lab.of Solid State Microstructures
,
Nanjing University
,
Nanjing 210008
,
China
材料科学技术（英文）
As a simulation of surface solidification of materials,quasi-two dimensional dendritic deposition of ammonium chloride(NH_4Cl)crystals from an aqueous solution film with free surface by vapourization was investigated by the in- situ observation technique.The depositing morphologies of NH_4Cl crystals are faceted and of growth laws differing from the three-dimensional case.Under low supersaturation,faceted dendrites formed,whereas the anisotropy in growth kinetics decreases with the increase of supersaturation.When vapourizing rate(supersaturation)is not very low, oscillations of growth rate.tip-radius and second arm spacing of the dendrites were observed.It is suggested that this dynamic phenomenon is attributed to the correlation between the convection-transfer effect induced by the surface tension gradient of solution film.and the driving force for deposition.
关键词:
surface deposition
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null
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null
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