方形开口腔内双扩散自然对流数值模拟
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摘要
对Soret和Dufour效应作用下的开口腔内双扩散自然对流进行了数值模拟。研究了在不同瑞利数Ra(10~3≤Ra≤10~7)、刘易斯数Le(0. 5≤Le≤8)、浮升力比N(-5≤N≤5)、Soret数和Dufour数(0≤Sr=Df≤0. 5)下,开口正方腔内温度场、浓度场、流场的影响及平均努塞尔数■和平均舍伍德数■的变化。结果表明,当N=-1时,■和■都达到最小值,腔内传热、传质效果最弱。当Ra较小时,改变Le对■、■影响不大;当Ra不变时,增大Le使得■逐渐降低、■逐渐升高,腔内传质增强,传热被削弱。另外,Le=1时,Soret和Dufour效应的变化对开口方腔内传热传质影响并不明显。■和■随着Soret和Dufour效应影响增强而增大,与Sr、Df为0时对比,Sr、Df从0. 1增大到0. 5时,■增加了10. 4%到58. 0%,■增加了3. 4%到13. 1%。
The numerical simulation of the double-diffusion natural convection with Soret and Dufour effects in a square open cavity was developed. The temperature field,concentration field,flow field,the average Nusselt and Sherwood number were investigated for different Rayleigh number( 10~3≤Ra≤10~7),Lewis number( 0. 5≤Le≤8),buoyancy ratio(-5≤N≤5),Soret and Dufour number( 0≤Sr = Df≤0. 5). The numerical results showed that the average Nusselt and Sherwood number reached minimum value when buoyancy ratio was -1,meanwhile the heat and mass transfer in the open cavity was the weakest. It was virtually no effect to the average Nusselt and Sherwood number by changing Lewis number when Rayleigh number was small. With a fixed Rayleigh number,the average Nusselt and Sherwood number gradually decreased and increased respectively as the increase of Le,which enhanced the mass transfer and weakened the heat transfer. Moreover,the effect of changing Soret and Dufour effect on the heat and mass transfer in a square open cavity was not obvious at Le = 1. Both ■ and ■ increased as the Sr and Df increasing,when the Df and Sr simultaneously increased from 0. 1 to 0. 5 and compared with Sr = Df = 0,■ increased by 10. 4% to 58. 0% and ■ increased by 3. 4% to 13. 1%,respectively.
The numerical simulation of the double-diffusion natural convection with Soret and Dufour effects in a square open cavity was developed. The temperature field,concentration field,flow field,the average Nusselt and Sherwood number were investigated for different Rayleigh number( 10~3≤Ra≤10~7),Lewis number( 0. 5≤Le≤8),buoyancy ratio(-5≤N≤5),Soret and Dufour number( 0≤Sr = Df≤0. 5). The numerical results showed that the average Nusselt and Sherwood number reached minimum value when buoyancy ratio was -1,meanwhile the heat and mass transfer in the open cavity was the weakest. It was virtually no effect to the average Nusselt and Sherwood number by changing Lewis number when Rayleigh number was small. With a fixed Rayleigh number,the average Nusselt and Sherwood number gradually decreased and increased respectively as the increase of Le,which enhanced the mass transfer and weakened the heat transfer. Moreover,the effect of changing Soret and Dufour effect on the heat and mass transfer in a square open cavity was not obvious at Le = 1. Both ■ and ■ increased as the Sr and Df increasing,when the Df and Sr simultaneously increased from 0. 1 to 0. 5 and compared with Sr = Df = 0,■ increased by 10. 4% to 58. 0% and ■ increased by 3. 4% to 13. 1%,respectively.
引文
[1] TURNER J S. Double-diffusive phenomena[J]. Annual Review of Fluid Mechanics,1974,6(6):37-55.
[2] ZHAO F Y,LIU D,TANG G F. Natural convection in a porous enclosure with a partial heating and salting element[J]. International Journal of Thermal Sciences,2008,47(5):569-583.
[3] CHAMKHA A J,Al-NASER H. Double-diffusive convection in an inclined porous enclosure with opposing temperature and concentration gradients[J]. International Journal of Thermal Sciences,2001,40(3):227-244.
[4]夏吉良,辛明道,张洪济.局部内热源和外部加热同时作用时部分开口空腔内自然对流的数值研究[J].工程热物理学报,1991,12(1):69-73.
[5]陈宝明,王补宣,张立强,等.多孔介质传热传质中耦合扩散效应的研究[J].工程热物理学报,2004,25(s1):125-128.
[6] BROWN N M,LAI F C. Correlations for combined heat and mass transfer from an open cavity in a horizontal channel[J]. International Communications in Heat&Mass Transfer,2005,32(8):1000-1008.
[7] NAWAZ M,HAYAT T,Al SAEDI A. Dufour and Soret effects on MHD flow of viscous fluid between radially stretching sheets in porous medium[J].应用数学和力学(英文版),2012,33(11):1403-1418.
[8]施楣梧,姚穆.纺织品热湿传递中的交叉效应[J].西安工程大学学报,2001,15(2):29-32.
[9]童艳,施明恒,龚延风.竖井型自然通风公路隧道气流与污染问题研究[J].建筑热能通风空调,2009,28(4):18-22.
[10]陶文铨.数值传热学(第2版)[M].西安:西安交通大学出版社,2010.
[11] PATANKAR S V. Numerical heat transfer and fluid flow[M]. Washington D C:Hemisphere,1980.
[12] REN Q,CHAN C L. Numerical study of double-diffusive convection in a vertical cavity with Soret and Dufour effects by lattice Boltzmann method on GPU[J]. International Journal of Heat&Mass Transfer,2016,93:538-553.
[2] ZHAO F Y,LIU D,TANG G F. Natural convection in a porous enclosure with a partial heating and salting element[J]. International Journal of Thermal Sciences,2008,47(5):569-583.
[3] CHAMKHA A J,Al-NASER H. Double-diffusive convection in an inclined porous enclosure with opposing temperature and concentration gradients[J]. International Journal of Thermal Sciences,2001,40(3):227-244.
[4]夏吉良,辛明道,张洪济.局部内热源和外部加热同时作用时部分开口空腔内自然对流的数值研究[J].工程热物理学报,1991,12(1):69-73.
[5]陈宝明,王补宣,张立强,等.多孔介质传热传质中耦合扩散效应的研究[J].工程热物理学报,2004,25(s1):125-128.
[6] BROWN N M,LAI F C. Correlations for combined heat and mass transfer from an open cavity in a horizontal channel[J]. International Communications in Heat&Mass Transfer,2005,32(8):1000-1008.
[7] NAWAZ M,HAYAT T,Al SAEDI A. Dufour and Soret effects on MHD flow of viscous fluid between radially stretching sheets in porous medium[J].应用数学和力学(英文版),2012,33(11):1403-1418.
[8]施楣梧,姚穆.纺织品热湿传递中的交叉效应[J].西安工程大学学报,2001,15(2):29-32.
[9]童艳,施明恒,龚延风.竖井型自然通风公路隧道气流与污染问题研究[J].建筑热能通风空调,2009,28(4):18-22.
[10]陶文铨.数值传热学(第2版)[M].西安:西安交通大学出版社,2010.
[11] PATANKAR S V. Numerical heat transfer and fluid flow[M]. Washington D C:Hemisphere,1980.
[12] REN Q,CHAN C L. Numerical study of double-diffusive convection in a vertical cavity with Soret and Dufour effects by lattice Boltzmann method on GPU[J]. International Journal of Heat&Mass Transfer,2016,93:538-553.