Research Commons
      • Browse 
        • Communities & Collections
        • Titles
        • Authors
        • By Issue Date
        • Subjects
        • Types
        • Series
      • Help 
        • About
        • Collection Policy
        • OA Mandate Guidelines
        • Guidelines FAQ
        • Contact Us
      • My Account 
        • Sign In
        • Register
      View Item 
      •   Research Commons
      • University of Waikato Research
      • Computing and Mathematical Sciences
      • Computing and Mathematical Sciences Papers
      • View Item
      •   Research Commons
      • University of Waikato Research
      • Computing and Mathematical Sciences
      • Computing and Mathematical Sciences Papers
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.

      Transport theory and the WKB approximation for interplanetary MHD fluctuations

      Matthaeus, William H.; Zhou, Ye; Zank, Gary P.; Oughton, Sean
      Thumbnail
      Files
      Transport theory.pdf
      3.240Mb
      DOI
       10.1029/94ja02326
      Find in your library  
      Citation
      Export citation
      Matthaeus, W. H., Zhou, Y., Zank, G. P., & Oughton, S. (1994). Transport theory and the WKB approximation for interplanetary MHD fluctuations. Journal of Geophysical Research, 99(A12), 23421-23430.
      Permanent Research Commons link: https://hdl.handle.net/10289/8621
      Abstract
      An alternative approach, based on a multiple scale analysis, is presented in order to reconcile the traditional WKB approach to the modeling of interplanetary fluctuations in a mildly inhomogeneous large-scale flow with a more recently developed transport theory. This enables us to compare directly, at a formal level, the inherent structure of the two models. In the case of noninteracting, incompressible (Alfvén) waves, the principle difference between the two models is the presence of leading-order couplings (called “mixing effects”) in the non-WKB turbulence model which are absent in a WKB development. Within the context of linearized MHD, two cases have been identified for which the leading order non-WKB “mixing term” does not vanish at zero wavelength. For these cases the WKB expansion is divergent, whereas the multiple-scale theory is well behaved. We have thus established that the WKB results are contained within the multiple-scale theory, but leading order mixing effects, which are likely to have important observational consequences, can never be recovered in the WKB style expansion. Properties of the higher-order terms in each expansion are also discussed, leading to the conclusion that the non-WKB hierarchy may be applicable even when the scale separation parameter is not small.
      Date
      1994
      Type
      Journal Article
      Collections
      • Computing and Mathematical Sciences Papers [1454]
      Show full item record  

      Usage

      Downloads, last 12 months
      60
       
       
       

      Usage Statistics

      For this itemFor all of Research Commons

      The University of Waikato - Te Whare Wānanga o WaikatoFeedback and RequestsCopyright and Legal Statement