Dear List,

sorry, we accidentally branched off the discussion from the list while
answering.

To summarize:
 - yay and welcome!
 - we meet after Jakobs defense in the week of March 19th+


All the best,
Axel

On 2/27/18 11:14 PM, Jakob Ameres Jakob.Ameres@ipp.mpg.de wrote:
> Dear all,
>
> given the portability of PICONGPU on CPU with the "omp2b" I will try to
> integrate some advanced PIC algorithms developed in the NMPP division at
> IPP and TUM in Garching based on the current development branch. The
> charge conserving scheme of Esirkepov can actually be reformulated as a
> strong Ampere/weak Faraday GEMPIC (geometric
> PIChttps://doi.org/10.1017/S002237781700040X
> <https://doi.org/10.1017/S002237781700040X>) algorithm with linear
> finite elements for Vlasov-Maxwell. The only thing way off is the time
> discretization which one can change to a Hamiltionan splitting providing
> very good energy conservation and additionally a momentum conservation
> depending on the spline degree. As a start I would use the particle mesh
> interface as it is and just change the time integrator. If this works
> out improvements/features should be:
>
>  * Hamiltonian Vlasov-Maxwell splitting of high order (using composition)
>  * Standard Vlasov-Maxwell (Poisson) single species test cases for
>    comparison against a given dispersion relation such as Landau
>    damping, Bump-on-Tail instability, Weibel and Weibel streaming
>    instability.
>  * High order finite element field solver using B-Splines of arbitrary
>    degree (this is not the same as changing the particle shape)
>  * Splitting methods for strong magnetic field
>    (https://doi.org/10.1103/PhysRevE.92.063310)
>  * Extension to fully energy and momentum conserving Particle in Fourier
>  * Variance reduction by control variates (an enhanced delta-f scheme)
>  * Quasi random numbers in order to improve the devastating 1/sqrt(N)
>    convergence to 1/N. Given the large particle numbers typically used
>    this would massively reduce the noise. (Eventually use boost
>    https://github.com/boostorg/random/pull/36 or GSL)
>
> Is someone else working on similar objectives? What is the current
> status of Esirkepovs scheme in devel?
>
> Concerning the standard test-cases for PIC, are they already implemented
> somewhere else?
>
> As I am completely new to the code itself, I would very much appreciate
> any help pointing me in the right direction, which files to look at or
> what may be possible to be reused or a good starting point. Actually I
> am very thankful for any comments. If it is possible I could also come
> to Dresden for a coding session.
>
> Best regards,
>
> Jakob Ameres
>

--

Axel Huebl
Phone: +49 351 260 3582
Institute of Radiation Physics
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