@article{PrattBusseMuelleretal.2017,
  author    = {Pratt, Jane and Busse, Angela and Mueller, W-C and Watkins, Nikolas W. and Chapman, Sandra C.},
  title     = {Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection},
  series = {New journal of physics : the open-access journal for physics},
  volume    = {19},
  journal   = {New journal of physics : the open-access journal for physics},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/aa6fe8},
  pages     = {18},
  year      = {2017},
  abstract  = {We investigate the utility of the convex hull of many Lagrangian tracers to analyze transport properties of turbulent flows with different anisotropy. In direct numerical simulations of statistically homogeneous and stationary Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD Boussinesq convection a comparison with Lagrangian pair dispersion shows that convex hull statistics capture the asymptotic dispersive behavior of a large group of passive tracer particles. Moreover, convex hull analysis provides additional information on the sub-ensemble of tracers that on average disperse most efficiently in the form of extreme value statistics and flow anisotropy via the geometric properties of the convex hulls. We use the convex hull surface geometry to examine the anisotropy that occurs in turbulent convection. Applying extreme value theory, we show that the maximal square extensions of convex hull vertices are well described by a classic extreme value distribution, the Gumbel distribution. During turbulent convection, intermittent convective plumes grow and accelerate the dispersion of Lagrangian tracers. Convex hull analysis yields information that supplements standard Lagrangian analysis of coherent turbulent structures and their influence on the global statistics of the flow.},
  language  = {en}
}
@article{FeudelTuckermanGellertetal.2015,
  author    = {Feudel, Fred and Tuckerman, L. S. and Gellert, Marcus and Seehafer, Norbert},
  title     = {Bifurcations of rotating waves in rotating spherical shell convection},
  series = {Physical Review E},
  volume    = {92},
  journal   = {Physical Review E},
  number    = {5},
  publisher = {American Physical Society},
  address   = {Woodbury},
  issn      = {1539-3755},
  doi       = {10.1103/PhysRevE.92.053015},
  year      = {2015},
  abstract  = {The dynamics and bifurcations of convective waves in rotating and buoyancy-driven spherical Rayleigh-Benard convection are investigated numerically. The solution branches that arise as rotating waves (RWs) are traced by means of path-following methods, by varying the Rayleigh number as a control parameter for different rotation rates. The dependence of the azimuthal drift frequency of the RWs on the Ekman and Rayleigh numbers is determined and discussed. The influence of the rotation rate on the generation and stability of secondary branches is demonstrated. Multistability is typical in the parameter range considered.},
  language  = {en}
}