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Jörg Schumacher

How can numerical simulations contribute?. Jörg Schumacher Theoretical Fluid Mechanics Department of Mechanical Engineering Technische Universität Ilmenau Germany. EuTuCHe Workshop Geneva, 23.–25.04.2007. Supercomputing.

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Jörg Schumacher

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  1. How can numerical simulations contribute? Jörg Schumacher Theoretical Fluid Mechanics Department of Mechanical Engineering Technische Universität Ilmenau Germany EuTuCHe Workshop Geneva, 23.–25.04.2007

  2. Supercomputing • More and more organized on European scale (Petaflop Project Pace) • DEep Computing Initiative within DEISA → 2 turbulence projects (2006/2007) • Resolution of the most intensive gradients in turbulence at Rl~100 on a 20483 • 800,000 CPUh on 512 CPUs (1.9Tbyte RAM) • 1 velocity snapshot = 68 Gbyte • Quasi-Lagrangian analysis in 513 around 100 Lagrangian tracers (700 Gbytes) • UNICORE platform for Grid computing • Parallel NetCDF for I/O

  3. Case 1: Cartesian Cell • Cartesian geometry (x,y,z) • Ra=107–109 • Pr=0.7 (later Pr > 1) • Aspect ratio: G=L/H=2-32 • Free-slip boundaries in z • Equidistant grid • Periodic side walls Geometry and Parameters H L

  4. Temperature Profile Pr=0.7 Ra=1.1×107 G=2 Rl=80 Nu=27.85 0.56 228 TE

  5. Case 2: Cylindrical Cell (Verzicco & Orlandi, JCP 1996) Geometry and Parameters • Cylindrical geometry (r,q,z) • Ra=107–1012 • Pr=0.7 (later Pr > 1) • Aspect ratio: G=L/H=1, 3, 5 • No-slip boundaries for flow • Non-equidistant grid • Temperature fixed at bottom/top • Adiabatic side walls L H

  6. Nusselt Number Convergence • Pr=0.7 • Ra=107 • =3 • Rl=(Ra/Pr)1/4 ~100 • Nu=16.06 0.05 151 TE

  7. Towards Large G Example: Sustain resolution & Double G Number of lateral grid points grows with G2 if the strong resolution constraints are sustained!

  8. Contributions (I) Direct participation Parallel data processing Database for later use Experiment Indirect participation Associated suprcomputing projects on classical/quantum turbulence

  9. Contributions (II) • Resolution of high-Ra boundary layers • Transition from laminar to turbulent boundary layer at Ra>1011 • What are the differences to „classical“ boundary layers? • Detailed Lagrangian study of breakdown of wind for aspect ratios G >1 • Ultimate regime of convection? • M. Emran (Ilmenau) R. Verzicco (Bari)

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