Designing and running turbulence transport simulations using a distributed multiscale computing approach

• Multiscale simulation involving slow transport and fast turbulent timescales is one amongstthree key computational challenges for Magnetic Confinement Plasmas, as identified in thePRACE report “The Scientific Case for HPC in Europe 2012-2020”. Whereas in global gy-rokinetic simulation the main challenge is parallelization efficiency (global gyrokinetic codesscaling to a huge amount of cores), the difficulty of the mulstiscale approach rely more on easeand performance of coupling single scale models together. This coupling requires generic meth-ods which have to be efficient and portable, especially when one (or more) single scale model isexecuted remotely as it may require specific hardware, bigger HPC systems or local databasesaccess.The MAPPER project is developing a software infrastructure dedicated to the design and theexecution of such distributed multiscale applications. It relies on a coupling library (MUSCLE)and few other to control the workflow execution and perform data communication betweenthe different single scale components (“kernels”). Communication is done in a transparent waywhether the kernels run locally or on a remote HPC system.We have implemented such application by using the MAPPER infrastructure and stand alonecodes developed within the EFDA Integrated Tokamak Modelling (ITM): 1-D transport equa-tions solver, 2-D geometry given by an equilibrium code, and transport coefficients given by a3-D fluxtube code. Due to the non-intrusive approach of the coupling library and to ITM efforton generic data structures, implementation of kernels is straightforward and the whole appli-cation is modular. This contribution presents the implementation, performance and preliminaryresults obtained with such multiscale method applied on present-day Tokamak configurations.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datavetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

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