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SUMMARY:Slope-limited transport schemes using icosahedral hexagonal grid -
  Sarvesh Kumar Dubey\,   (Indian Institute of Technology)
DTSTART:20120925T080000Z
DTEND:20120925T082500Z
UID:TALK40092@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:In this work two simple advection schemes for unstructured mes
 hes are proposed and implemented over spherical icosahedral-hexagonal grid
 s. One of them is fully discrete in space and time while the other one is 
 a semi discrete scheme with third order RungeKutta time integration. Both
  schemes use cell-wise linear reconstruction. We therefore also present tw
 o possible candidates for consistent gradient discretization over general 
 grids. These gradients are designed in a finite volume sense with an adequ
 ate modification to guarantee convergence in the absence of a special grid
  optimization. Monotonicity of the advection schemes is enforced by a slop
 e limiter\, at contrast with the widely used of posterior approach of flu
 x-corrected transport (FCT). Convergence of the proposed gradient reconstr
 uction operators is verified numerically. It is found that the proposed mo
 dification is indeed necessary for convergence on non-optimized grids. Rec
 ently proposed advection test cases are used to evaluate the performance o
 f the slope-limited advection schemes. It is verified that they are conver
 gent and positive. We also compare these schemes to a variant where positi
 vity is enforced by the FCT approach. FCT produces slightly less diffusion
  but it seems to be at the price of some nonphysical anti-diffusion. These
  results suggest that the proposed slope limited advection schemes are a v
 iable option for icosahedral-hexagonal grids over sphere. \n\n
LOCATION:Seminar Room 1\, Newton Institute
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