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Steady thermocapillary-buoyant convection in a shallow annular pool. Part 2: Two immiscible fluids 总被引:1,自引:0,他引:1
This work is devoted to the study of steady thermocapillary-buoyant convection in a system of two horizontal superimposed immiscible liquid layers filling a lateral heated thin annular pool.The governing equations are solved using an asymptotic theory for the aspect ratios ε→ 0.Asymptotic solutions of the velocity and temperature fields are obtained in the core region away from the cylinder walls.In order to validate the asymptotic solutions,numerical simulations are also carried out and the results are compared to each other.It is found that the present asymptotic solutions are valid in most of the core region.And the applicability of the obtained asymptotic solutions decreases with the increase of the aspect ratio and the thickness ratio of the two layers.For a system of gallium arsenide (lower layer) and boron oxide (upper layer),the buoyancy slightly weakens the thermocapillary convection in the upper layer and strengthens it in the lower layer. 相似文献
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环形液层内热毛细对流的线性稳定性分析 总被引:1,自引:0,他引:1
为了了解液层深度对热毛细对流不稳定性的影响,利用线性稳定性理论分析了内径为20 mm、外径为40 mm、深度为1~20 mm的环形液层内硅油(Pr=6.7)的热毛细对流,重点考察了发生热流体波的临界温差及热流体波的临界周向波数,结果表明,临界温差随液层深度的增加而降低.讨论了浮力对热流体波及其临界条件的影响,并证实了常重力条件下当液层厚度大于5 mm时,热流体波呈静止状态这一现象. 相似文献
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采用三维数值模拟方法研究了太阳能吸热器在有风环境下的混合对流热损失特性,得到了吸热器腔体内部的温度分布和采光口截面的速度分布以及对流热损失大小与倾角、风向的关系曲线。结果表明,与无风环境下太阳能吸热器对流热损失随倾角增加而单调减小的规律不同,有风环境下,太阳能吸热器混合对流热损失同时受到环境风和倾角的共同影响,且规律较为复杂。当风向背对采光口时,吸热器混合对流热损失在不同倾角下随风向的变化较小,但当风向正对采光口时,吸热器混合对流热损失随风向的变化较为剧烈,受到倾角的影响也较为显著。 相似文献
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Biodegradable monomethoxy(polyethyleneglycol)-poly(lactide-co-glycolide)-monomethoxy(poly-ethyleneglycol) (PELGE) copolymers were synthesized by ring-opening polymerization to formulate plasmid DNA loaded nanoparticles. A double emulsion method with polyvinyl alcohol as the emulsifier in the external aqueous phase was employed to prepare nanoparticles. The effects of monomethoxypoly(ethyleneglycol) (mPEG) segments in the polymer on particle size, zeta potential, encapsulation efficiency and in vitro release were investigated. It was found that the introduction of a certain amount of hydrophilic mPEG segments in the copolymer chains could improve the affinity of copolymer with plasmid DNA and enhance the emulsification ability of the copolymer. Thus DNA loaded nanoparticles with smaller particle sizes and higher encapsulation efficiencies were obtained by using PELGE copolymer as the matrix. 相似文献
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为了了解勾形磁场对CdZnTe晶体生长质量的影响,利用有限元法对坩埚内的热量和动量传递过程进行了全局数值模拟。假定熔体和气相中的流动都为准稳态轴对称层流,研究了B_o(磁场轴线与晶体-坩埚界面的交点的磁场强度的轴向分量)为0 T,0.5 T,1.0 T,1.5 T,2.0 T,2.5 T,3.0 T时的CdZnTe晶体生长过程。结果表明:勾形磁场能有效抑制熔体内的流动,会产生由洛仑兹力、表面张力和浮力共同驱动的涡胞。随着磁场强度的增加,传热向导热型转变,熔体内最大流函数逐渐减小,抑制作用增强。 相似文献
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为了探究Soret效应对具有自由表面的圆柱形浅液池内双组分溶液热对流过程的影响, 通过实验观察了质量分数为50%的正癸烷/正己烷混合溶液在不同深宽比的液池内流动失稳后的自由表面耗散结构及液池内的温度波动. 结果表明, 双组分溶液流动失稳的临界热毛细Reynolds数小于纯工质的值, 且其随液层深宽比的变化规律与纯工质相同. 当深宽比小于0.0848时, 流动失稳后在自由表面观察到热流体波, 监测点处温度波动主频随热毛细Reynolds数增大而增加; 当深宽比大于0.0848时, 随热毛细Reynolds数的增大, 流动失稳后自由表面依次呈现轮辐状、花苞状、分离-合并-分离交替变化的条纹状结构. 相似文献
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