Blar i forfatter "Wiesenberger, Matthias"

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    • Amplitude and size scaling for interchange motions of plasma filaments 

      Kube, Ralph; Wiesenberger, Matthias; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-07)
      The interchange dynamics and velocity scaling of blob-like plasma filaments are investigated using a two-field reduced fluid model. For incompressible flows due to buoyancy, the maximum velocity is proportional to the square root of the relative amplitude and the square root of its cross-field size. For compressible flows in a non-uniform magnetic field, this square root scaling only holds ...

    • Beyond the Oberbeck-Boussinesq and long wavelength approximation 

      Held, Markus; Wiesenberger, Matthias (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-22)
      We present the first simulations of a reduced magnetized plasma model that incorporates both arbitrary wavelength polarization and non-Oberbeck–Boussinesq effects. Significant influence of these two effects on the density, electric potential and <i><b>E</i></b> × <i><b>B</i></b> vorticity and non-linear dynamics of interchange blobs are reported. Arbitrary wavelength polarization implicates so-called ...

    • A finite volume flux coordinate independent approach 

      Wiesenberger, Matthias; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-03)
      We present a novel family of schemes as the merging between a one-dimensional advection scheme with the flux coordinate independent approach. The scheme can be used to discretize the field-aligned NavierStokes equations in three dimensions. Our approach consists of three major steps: (i) the formulation of the one-dimensional scheme in a locally field-aligned coordinate system, (ii) a numerical ...

    • Long-wavelength closures for collisional and neutral interaction terms in gyro-fluid models 

      Wiesenberger, Matthias; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2022)
      A collisional gyro-fluid model is presented. The goal of the model is edge and scrape-off layer turbulence. The emphasize in the model derivation heavily lies on "implementability" with today's numerical methods. This translates to an avoidance of infinite sums, strongly coupled equations in time and intricate elliptic operator functions. The resulting model contains the four moments density, parallel ...

    • Numerical evaluation of line, surface and toroidal integrals on level sets of toroidally symmetric functions 

      Wiesenberger, Matthias; Gerrú, Raul; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-05)
      We investigate strategies to numerically integrate closed lines and surfaces that are implicitly defined by level sets (iso-contours) of continuously differentiable toroidally symmetric functions. The “grid-transform” approach transforms quantities given in non-surface-aligned coordinates onto a numerically constructed surface-aligned grid. Here, line and surface integrals, as well as so-called ...

    • Unified transport scaling laws for plasma blobs and depletions 

      Wiesenberger, Matthias; Held, Markus; Kube, Ralph; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-06-14)
      We study the dynamics of seeded plasma blobs and depletions in an (effective) gravitational field. For incompressible flows, the radial center of mass velocity of blobs and depletions is proportional to the square root of their initial cross-field size and amplitude. If the flows are compressible, this scaling holds only for ratios of amplitude to size larger than a critical value. Otherwise, the ...