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DTSTAMP:20190719T085745Z
LOCATION:HG D 3.2
DTSTART;TZID=Europe/Stockholm:20190614T150000
DTEND;TZID=Europe/Stockholm:20190614T153000
UID:submissions.pasc-conference.org_PASC19_sess157_msa283@linklings.com
SUMMARY:OpenACC and Adaptive Mesh Refinement for Nek5000
DESCRIPTION:Minisymposium\nComputer Science and Applied Mathematics, Emerg
 ing Application Domains, Physics, Engineering\n\nOpenACC and Adaptive Mesh
  Refinement for Nek5000\n\nSchlatter, Gong, Otero, Peplinski, Offermans...
 \n\nNek5000 is an open-source code for the simulation of incompressible fl
 ows. Nek5000 is widely used in a broad range of applications, including th
 e study of wall turbulence, thermo-hydraulics and flow stability problems.
  In this talk, two aspects towards exascale for Nek5000 are discussed: 1) 
 OpenACC acceleration for use with GPUs, and 2) adaptive mesh refinement fo
 r optimised automatic meshes. In the first part, we will summarize our wor
 k on porting and optimizing the most time-consuming parts of Nek5000 to th
 e GPU systems, namely the PCG/GMRES solvers for velocities and pressure fi
 elds using the OpenACC directives. In addition, we will present the perfor
 mance results of the OpenACC version for typical production problems on mu
 lti-GPU system. In the second part, we present our implementation of h-typ
 e AMR framework. It is based on splitting/merging elements keeping polynom
 ial order constant across the whole computational domain. Refinement and c
 oarsening is driven by spectral error indicator or adjoint based error est
 imator. AMR may increase the solver complexity by influencing code perform
 ance and stability. We discuss those aspects presenting fully AMR simulati
 ons of a canonical flows like flow over periodic hill and a turbulent flow
  around a NACA4412 wing section
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