...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Measurement of particle rotation in a saltation layer
【24h】

Measurement of particle rotation in a saltation layer

机译：盐析层中颗粒旋转的测量

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

Two computational methods to measure particle rotations from shadow images of sand particles saltating in a wind tunnel are presented. One method calculates the maximum of the cross-correlations through multiple angular rotations of an imaged particle. The second method polar transforms both images and then calculates the correlation coefficient for multiple pixel displacements in the θ axis, corresponding to particle rotations. The results from both methods were analysed as a function of height above sand bed (3.7-33.4 mm) and particle size (0.32-0.93mm equivalent mean diameter). Our results indicate little evidence that particle rotation speeds depend on either their size or height above the sand bed. Though similar results were obtained from both methods, there existed different advantages and disadvantages between the methods. Erroneous results likely arose from particles that were inadequately described by a 2-D rotation axis, or from poorly imaged particles. At a wind tunnel speed of about 12 m/s, most particles rotated at around 300-400 rev/s. Negative rotations were also found, and their proportion was approximately 15% within the total range of -450 to 850 rev/s. The ratio of displacement kinetic energy to rotation energy was compared across the various groups and had values between 15 and 40. The quotient showed little dependence on height, though decreased with increasing particle size. Wider applicability of the measurement methodology to study snow particle rotation is also discussed.
机译：提出了两种从风洞中盐化的沙粒阴影图像中测量粒子旋转的计算方法。一种方法通过成像粒子的多次角度旋转来计算互相关的最大值。第二种方法是对两个图像进行极坐标变换，然后计算对应于粒子旋转的θ轴上多个像素位移的相关系数。两种方法的结果均作为沙床上方高度（3.7-33.4毫米）和粒径（0.32-0.93毫米等效平均直径）的函数进行分析。我们的结果表明，几乎没有证据表明粒子旋转速度取决于其大小或沙床上方的高度。尽管从这两种方法获得了相似的结果，但是这两种方法之间存在优缺点。错误的结果可能是由于二维旋转轴描述不充分的粒子或成像效果差的粒子引起的。在大约12 m / s的风洞速度下，大多数粒子以大约300-400 rev / s的速度旋转。还发现负旋转，其比例在-450至850 rev / s的总范围内约为15％。比较了各个组的位移动能与旋转能之比，其值在15到40之间。该商对高度的依赖性不大，尽管随粒径的增加而降低。还讨论了测量方法在研究雪粒旋转方面的广泛适用性。

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