• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>International Journal of Heat and Mass Transfer >Calculation of Knudsen layers and jump conditions using the linearised G13 and R13 moment methods
【24h】

Calculation of Knudsen layers and jump conditions using the linearised G13 and R13 moment methods

机译：使用线性化的G13和R13矩方法计算Knudsen层和跳跃条件

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

For gas flows in micro-channels the molecular mean free path is often comparable to the channel dimensions and the flow must be modelled using one of the methods of non-continuum gas dynamics. For slip-flow or lower transition regime calculations the Grad 13-moment (G13) method or its extension the Regularised 13-moment (R13) method has been proposed. The R13 method is assumed to be an improvement over the G13 because it can capture, at least to some extent, Knudsen layers close to solid surfaces. This paper investigates the capabilities of the two methods by using them to address the classical problems of viscous slip, temperature jump and thermal creep. For the linearised equations it is possible to obtain analytical solutions and these provide physical insight as well as numerical values. The analysis shows that the Knudsen layer associated with temperature and normal stress decouples from the layer associated with velocity and heat flux. Comparison with more accurate solutions of the kinetic equation shows that the LR13 method underpredicts the velocity slip and temperature jump coefficients by about 10% and only provides a slight improvement over the much simpler LG13 method. Furthermore, the Knudsen layer velocity and temperature profiles bear only a superficial resemblance to more accurate solutions. For reasons that are unclear, the calculation of the thermal creep flow is very much more successful. It is concluded that considerable improvements need to be made before the LR13 method becomes a reliable technique for solving non-continuum flow problems.
机译：对于在微通道中的气体流动，分子平均自由程通常与通道尺寸相当，并且必须使用非连续气体动力学方法之一对流量进行建模。对于滑流或较低过渡态的计算，提出了Grad 13矩（G13）方法或其扩展，正则化13矩（R13）方法。 R13方法被认为是对G13的改进，因为它可以至少在一定程度上捕获靠近实体表面的Knudsen层。本文通过使用这两种方法来解决粘滑，温度跳跃和热蠕变的经典问题，从而研究了这两种方法的功能。对于线性方程，可以获取解析解，这些解析解提供了物理洞察力以及数值。分析表明，与温度和法向应力相关的克努森层与与速度和热通量相关的层解耦。与动力学方程的更精确解的比较表明，LR13方法低估了速度滑移系数和温度跳跃系数约10％，并且仅比简单得多的LG13方法略有改进。此外，Knudsen层的速度和温度曲线与更精确的解决方案仅在表面上相似。由于不清楚的原因，热蠕变流量的计算非常成功。结论是，在LR13方法成为解决非连续流问题的可靠技术之前，需要进行大量改进。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号