From: "Axel Huebl a.huebl@hzdr.de" Received: from [210.136.188.141] (account huebl@hzdr.de HELO [192.168.64.70]) by hzdr.de (CommuniGate Pro SMTP 6.2.0) with ESMTPSA id 18833568 for picongpu-users@hzdr.de; Sat, 03 Mar 2018 20:13:37 +0100 Subject: Re: Geometric PIC for PICONGPU To: picongpu-users@hzdr.de References: Organization: HZDR Message-ID: Date: Sun, 4 Mar 2018 04:14:18 +0900 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit 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 > ) 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 http://www.hzdr.de/crp Helmholtz-Zentrum Dresden - Rossendorf (HZDR) Bautzner Landstr. 400 | 01328 Dresden | Germany Board of Directors: Prof. Dr. Dr. h. c. Roland Sauerbrey, Dr. Ulrich Breuer Company Registration Number VR 1693, Amtsgericht Dresden