Direct and Large Eddy Simulation

The bi-annual Workshop series on Direct and Large Eddy Simulation (DLES) which started in 1994 focuses on modern techniques to simulate turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structure. With the growing capacities of modern computers, this approach has been gaining more and more interest over the years and will undoubtedly be further enhanced and applied. The goal of the bi-annual DLES workshop series is to establish the state-of-the-art of DNS, LES and related techniques for the computation and modelling of turbulent and transitional flows.

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Code of the Month vol.6 “Neko by CEEC” — PUBLIC event

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Recent trends and advancements including more diverse and heterogeneous hardware in High-Performance Computing are challenging scientific software developers in their pursuit of good performance and efficient numerical methods. As a result, the well-known maxim “software outlives hardware” may no longer necessarily hold true, and researchers are today forced to re-factor their codes to leverage these powerful new heterogeneous systems. We present Neko – a portable framework for high-fidelity spectral element flow simulations. Unlike prior works, Neko adopts a modern object-oriented Fortran 2008 approach, allowing multi-tier abstractions of the solver stack and facilitating various hard- ware backends ranging from general-purpose processors, accelerators down to exotic vector processors and Field Programmable Gate Arrays (FPGAs) via Neko’s device abstraction layer. Focusing on Neko’s performance and exascale readiness, we outline the optimisation and algorithmic work necessary to ensure scalability and performance portability across a wide range of platforms. Finally, we present performance measurements on a wide range of accelerated computing platforms, including the EuroHPC pre-exascale systems LUMI and Leonardo, where Neko achieves excellent parallel efficiency for an extreme-scale direct numerical simulation (DNS) of turbulent thermal convection using up to 80% of the entire LUMI supercomputer.

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Neko – a European code development effort shortlisted for the 2023 ACM Gordon Bell Prize

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Come listen to our own Niclas Jansson talk about his work on NEKO, which has been shortlisted for the 2023 ACM Gordon Bell Prize. We have the great fortune of being able to build on this work during the cEEC project. Learn more in his interview at the LUMI stand (booth 206)!

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1st CEEC Community Workshop: Energy-Efficient, Fault Resilient, and Scalable Solvers for CFD Codes

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Join us for our first annual community workshop! The energy consumption constraint for large-scale computing encourages scientists to revise the architecture design of hardware but also applications, algorithms, as well as the underlying working/ storage precision. The main aim is to make the computations energy-efficient (aka sustainable) and robust numerically but also in terms of fault tolerance. On the level of algorithmic solutions, we propose to utilize all provided resources wisely by exhibiting algorithms to computation overlapping but even more communication overlapping strategies. We also promote mixed-precision strategies with the aid of computer arithmetic tools like VerifiCarlo and its variable precision backend. Hence, before lowering precision, one must ensure that the simulation is numerically correct, e.g. by relying on alternative floating-point models/ rounding to pinpoint numerical bugs and to estimate the accuracy. We also work on fault tolerant and resilient algorithms, adaptivity and meshing/ mesh refinement that adapt to the heterogeneous nature of current machines. Another issue discussed in the workshop is the adaptation of adjoint-based topology optimization methods to spectral-element CFD codes. Therefore, in this workshop, we will share our approaches, lessons learnt with preliminary results, and outline perspectives for the upcoming three years of the project.

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