Instability Waves in Cold Airflows.

• NONAKA Yoshimasa

  Department of Earth Science, Faculty of Education, Miyazaki University

Bibliographic Information

Other Title

• 冷気流に発生する不安定波動について

Abstract

This paper is a study of stability of the cold airflow. For this study I propose a model of cold air flow which is based upon Prandtl's model (1952) and assumes a rigid slip boundary at the top. Explaining the causes of instabilities, this paper follows the conditions proposed by Lindzen et al. (1985, 1986), under which overreflection can occur. And the numerical method adopting the third-order spline interpolation is used.<BR>It is shown that two types of disturbances are found, of which the first one arises mainly from the effect of the inflection point of the basic flow and the second one does mainly by the Rayleigh-Taylor type instability due to the change of the sign of potential temperature gradient. Moreover, the two kinds of waves peculiar to the cold airflow are caused by the latter effect.<BR>The critical Reynolds number Re_c becomes greater as the angle of the slope χ decreases, i. e., as the stratification effect increases. The critical condition for instability is approximately given as Ri_o< 0.023 when 2.5≤χ≤10°, where Ri_o is the overall Richardson number defined by Ri_o= 2cotχ/Re_c.

Journal

• Journal of Japan Society of Fluid Mechanics

  Journal of Japan Society of Fluid Mechanics 12 (4), 409-422, 1993

  The Japan Society of Fluid Mechanics

Keywords

• Cold airflow
• Over-reflection
• Inflection point instability
• Rayleigh-Taylor instability
• Spline interpolation

Details

• CRID: 1390282679673613440
• NII Article ID: 10008003779
• NII Book ID: AN00175191
• DOI: 10.11426/nagare1982.12.409
• ISSN: 21854912
• ISSN: 02863154
• Text Lang: ja
• Data Source:
  • JaLC
  • CiNii Articles
• Abstract License Flag: Disallowed