jörg schumacher
Post on 19-Jan-2016
39 Views
Preview:
DESCRIPTION
TRANSCRIPT
Jörg Schumacher Theoretical Fluid Mechanics
Department of Mechanical Engineering
Technische Universität Ilmenau
Germany
How can numerical simulations contribute?
EuTuCHe Workshop Geneva, 23.–25.04.2007
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 R~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
Case 1: Cartesian Cell
Cartesian geometry (x,y,z) Ra=107–109 Pr=0.7 (later Pr > 1) Aspect ratio: =L/H=2-32
Free-slip boundaries in z Equidistant grid Periodic side walls
Geometry and Parameters
H
L
Temperature Profile
Pr=0.7Ra=1.1×107
=2
R=80Nu=27.85 0.56
32Nu
HδT
1Δ
ηK
228 TE
129256256NNN zyx
Case 2: Cylindrical Cell
Cylindrical geometry (r,,z) Ra=107–1012 Pr=0.7 (later Pr > 1) Aspect ratio: =L/H=1
No-slip boundaries for flow Non-equidistant grid Temperature fixed at bottom/top Adiabatic side walls
(Verzicco & Orlandi, JCP 1996)
H
L
Geometry and Parameters
Nusselt Number Convergence
03.0Nu2
HδT
128165257NNN zrθ
4
3~K
Pr=0.7Ra=107
=3
R=(Ra/Pr)1/4 ~100Nu=16.06 0.05
3zθr ΔmaxRΔΔmaxΔ
~
151 TE
Towards Large
1ΓR 2ΓR
θ2Γ ΔR θ1Γ ΔR
Example:
Sustain resolution & Double
3z
θ1r2 ΔmaxΔ
RΔmaxΔ~
2R
zrθ12 NΓNΓN~~
2Γθ,Δ
Number of lateral grid points grows with if the strong resolution constraints are sustained!
Contributions (I)
Experiment
Parallel data processing Database for later use
Associated suprcomputing projects on classical/quantum turbulence
Direct participation
Indirect participation
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 >1 Ultimate regime of convection?
M. Emran (Ilmenau) R. Verzicco (Bari)
top related