An Assessment of the Efficiency of Nodal Discontinuous Galerkin Spectral Element Methods

Author(s):  
David A. Kopriva ◽  
Edwin Jimenez
2019 ◽  
Vol 81 (2) ◽  
pp. 820-844
Author(s):  
Marvin Bohm ◽  
Sven Schermeng ◽  
Andrew R. Winters ◽  
Gregor J. Gassner ◽  
Gustaaf B. Jacobs

2021 ◽  
Vol 88 (1) ◽  
Author(s):  
David A. Kopriva ◽  
Gregor J. Gassner ◽  
Jan Nordström

AbstractWe use the behavior of the $$L_{2}$$ L 2 norm of the solutions of linear hyperbolic equations with discontinuous coefficient matrices as a surrogate to infer stability of discontinuous Galerkin spectral element methods (DGSEM). Although the $$L_{2}$$ L 2 norm is not bounded in terms of the initial data for homogeneous and dissipative boundary conditions for such systems, the $$L_{2}$$ L 2 norm is easier to work with than a norm that discounts growth due to the discontinuities. We show that the DGSEM with an upwind numerical flux that satisfies the Rankine–Hugoniot (or conservation) condition has the same energy bound as the partial differential equation does in the $$L_{2}$$ L 2 norm, plus an added dissipation that depends on how much the approximate solution fails to satisfy the Rankine–Hugoniot jump.


Author(s):  
Daniel A. Nelson ◽  
Gustaaf B. Jacobs

We present an algorithm for computing forward-time finite-time Lyapunov exponents (FTLEs) using discontinuous-Galerkin (DG) operators. Passive fluid tracers are initialized at Gauss-Lobatto quadrature nodes and advected concurrently with direct numerical simulation (DNS) using DG spectral element methods. The flow map is approximated by a high-order polynomial and the deformation gradient tensor is then determined by the spectral derivative. Since DG operators are used to compute the deformation gradient, the algorithm is high-order accurate and is consistent with the DG methods used to compute the fluid solution. The method is validated with a benchmark of a periodic gyre, a vortex advected in uniform flow and the flow around a square cylinder. An exact equation for the FTLE of the advected vortex is derived.


2014 ◽  
Vol 76 (8) ◽  
pp. 522-548 ◽  
Author(s):  
Andrea D. Beck ◽  
Thomas Bolemann ◽  
David Flad ◽  
Hannes Frank ◽  
Gregor J. Gassner ◽  
...  

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