HR: 1340h
AN: NG23A-1184    [Abstracts]
TI: Nearly incompressible fluid III: Hydrodynamics and large-scale inhomogeneity
AU: * Hunana, P
EM: peter.hunana@email.ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California,, Riverside, CA 92521 United States
AU: Zank, G
EM: gary.zank@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California,, Riverside, CA 92521 United States
AU: Shaikh, D
EM: dastgeer@ucr.edu
AF: Institute of Geophysics and Planetary Physics, University of California,, Riverside, CA 92521 United States
AU: Matthaeus, W H
EM: yswhm@bartol.udel.edu
AF: Bartol Research Institute, The University of Delaware, Newark, DE 19716 United States
AU: Zhou, Y
EM: zhou3@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550-9234 United States
AB: The solar wind is an excellent example of a turbulent MHD fluid, and models based on an incompressible MHD description have had considerable success in explaining observations such as the Kolmogorov-like power spectrum in magnetic field fluctuations. However, fully developed solar wind fluctuations also show a Kolmogorov like density spectrum with spectral index $\kappa^{-5/3}$. These weakly compressible fluctuations cannot be described by isotropic homogeneous and isothermal incompressible fluid models. Nearly incompressible (NI) fluid theory, developed by Zank, Matthaeus and Brown is an appropriate model to describe the weakly compressible solar wind fluctuations. The theory is primarily developed for isotropic homogeneous fluctuations in solar wind. However, the solar wind possesses large scale gradients in the magnetic field, density and temperature. In order to describe these fluctuations in a self consistent manner, it is necessary to include large scale inhomogeneities in the NI model. Here we present an extension of the theory of NI fluids that includes large scale gradients in the solar wind background. The inhomogeneous flow modifies the leading order incompressible behavior of the fluid substantially in that: i) the divergence of the solar wind velocity fluctuations is non-solenoidal. ii) Incompressible density and pressure fields are driven by large-scale gradients in the solar wind. iii) Higher order compressible pressure fluctuations couple to large-scale gradients in the solar wind pressure and velocity fields. iv) The complete inhomogeneous NI hydrodynamics model, describing high plasma beta solar wind, possesses rich and complex nonlinear interactions that couple to the large scale gradients through a weak aspect ratio parameter (defined by the ratio of ambient small scale turbulence to the large scale solar wind).
DE: 2144 Interstellar gas
DE: 2159 Plasma waves and turbulence
DE: 2164 Solar wind plasma
DE: 2467 Plasma temperature and density
SC: Nonlinear Geophysics [NG]
MN: 2004 AGU Fall Meeting