Transcript Document

Center for Radiative Shock
Hydrodynamics
Introductory overview
R. Paul Drake
We will take you from overviews to specifics
•
This first presentation
– Motivation and introduction to the physical system
– Overview of the experiments and of the project
•
Overviews this morning
– Powell on the simulation
– Holloway on assessment of predictive capability
•
Code and verification this afternoon
– Toth on architecture and practices
– Myra on tests
•
Assessing predictive capability in the morning
– Bingham on our first integrated study
– Fryxell on 3D sensitivity runs
•
Posters today
– See the details and meet the people
•
You will see how our priorities have been driven by becoming able
to assess the capability of our code to predict our year 5 data.
Page 2
We find our motivation in astrophysical
connections
• Radiative shocks have strong
radiative energy transport that
determines the shock structure
Ensman & Burrows ApJ92
• Exist throughout astrophysics
– Supernovae, accretion, stars,
supernova remnants, collisions
• Our experiments
Reighard PoP07
– have behavior and
dimensionless parameters
relevant to shocks emerging
from supernovae
– We should see any important
unanticipated physics
– Good code test in any event
Page 3
A brief primer on shock wave structure
• Behind the shock, the faster sound waves connect the
entire plasma
shocked
Denser,
Hotter
Shock velocity, us
unshocked
Initial plasma
Mach number M > 1
Mach number
M = us / csound
Page 4
Shock waves become radiative when …
• radiative energy flux would exceed incoming material energy
flux
Ts4
ous3/2 unshocked
preheated
shocked
where post-shock temperature is proportional to us2.
• Setting these fluxes equal gives a threshold velocity of 60
km/s for our system:
Material
xenon gas
Density
6.5 mg/cc
Initial ion temperature
2 keV
Initial shock velocity
200 km/s
Typ. radiation temp.
50 eV
Page 5
The CRASH project began with several elements
• An experimental system that is
challenging to model and relevant to
NNSA, motivated by astrophysics
• A 3D adaptive, well scaled,
magnetohydrodynamic (MHD) code
with a 15 year legacy and many users
• A 3D deterministic radiative transfer
code developed for parallel platforms
• A strong V&V tradition with both codes
Space weather
simulation
• Some ideas about how to approach
“UQ” in general and specifically the
Assessment of Predictive Capability
Page 6
CRASH builds on a basic experiment
• Basic Experiment:
Radiography is the primary diagnostic.
Additional data from other diagnostics.
A. Reighard et al. Phys. Plas. 2006, 2007
F. Doss, et al. HEDP, submitted 2009
Grid
Schematic of radiograph
Page 7
We have identified key parameters for the
code/experiment comparison
• Key measurements at data time
– Basic (1D)
• Shock position
• Layer thickness
– Multi-D
• Distance of kink in shock
from tube wall
• Angle of xenon edge just
downstream of shock
Page 8
Our experimental sequence will improve and test
our assessment of predictive capability
•
A conceptually simple
experiment
– Launch a Be plasma down a
shock tube at ~ 200 km/s
•
Year 5 experiment
– Predict outcome and accuracy
before doing year 5 experiment
•
Goals
– Improve predictive accuracy
during project
– Demonstrate a predictive
uncertainty comparable to the
observed experimental
variability
– A big challenge and
achievement
Page 9
Last April we reported a CRASH 1.0 3D
simulation of the year 5 experiment
Initialized by calibrated laser code, to be discussed by Ken
Top view
Side view
Density
Temperature
2008 IRT: The project will live or die based on whether a
“reasonably good code” can be built
This font color highlights responses to 2008 IRT recommendations
Page 10
The CRASH research process incorporates
many UQ elements. Culture change is here.
Page 11
UQ considerations have driven
the project to date
• Had to become able to Assess Predictive Capability
– Develop a “reasonably good” code
– Code tests and physics tests
– “Drill-down” documentation system
–
–
–
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Variability of base experiment (10/08)
Early data to calibrate inputs (12/09)
Learn enough to define the CRASH UQ methodology
Tests of UQ methods
• We are using the tools we have assembled
– Going forward, UQ analysis must tell us what code to write,
what experiments to do, and what UQ to do
• Working independently on additional diagnostics
– X-ray and imaging Thomson Scattering
Page 12
We are organized to bring leadership and effort to
all areas where they are needed
•
Most of our team members participate in more than one area
(details in supplementary material)
Predictive Capability beyond traditional V&V
James Holloway, Co-PI, lead
Primary
Bruce Fryxell, chief scientist
Role
FTE
Professors
Research Scientists
Other staff
Graduate students
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2
Other staff
1.4
4
6
Code Development and Traditional V&V
Ken Powell, Co-PI, lead
Primary
Gabor Toth, Software Archit.
Role
FTE
Professors
1
Research Scientists
4
2.15
Other staff
2
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Scientific Computing
Quentin Stout, Co-PI, lead
Professors
Primary
Role
FTE
3
1
Modeling and Theory
Primary
Jointly led
Role
10
1
0
10
Professors
Research Scientists
Other staff
Graduate studens
Experiments
Paul Drake, Director, lead
Professors
Research Scientists
Other staff
Graduate studens
FTE
0.33
Primary
Role
FTE
1
1
0.8
1
6
We use our resource plan, our work plan, and UQ considerations
to inform priority decisions
Page 13
We have expanded our theoretical work
•
The IRT recommended more effort in analytic theory
•
Paul Drake has invested more time
– Enabled by contributions by Ken Powell and James Holloway
•
Ryan McClarren has a paper on the structure of this type of
radiative shock in draft form.
– Rob Lowrie (LANL) has collaborated on this.
•
Graduate student Forrest Doss continues to work on the analytic
theory of the shocked layer instability
•
Igor Sokolov has contributed considerably
•
Emilio Minguez (U.P. Madrid) has visited for opacity collaborations
•
We are working to engage Dmitri Ryutov (LLNL) and Sasha
Velikovich (NRL), who are interested
• We have a CRASH primer which will evolve
Page 14
CRASH will have other applications and users
• Solar group is already doing radMHD evolving from CRASH
• Our experiment team (students
funded variously) needs CRASH
• Already one other university is
eager to use our code (FSU)
• The labs will be users of our
trained people more than codes
• Our NIF team may become a
key user
– Experimental program is
making first university use of
NIF
– Excellent opportunity to
apply CRASH and see what
breaks
CRASH simulation of NIF
Radiative Hydrodynamic
Instability experiment at
7.0 ns: 2D, 600 x 80
Page 15
We intend to accomplish an important result
• Our unique intended contribution
– Be the first academic team
to use statistical Assessment of Predictive Capability
to guide improvements in simulations and field experiments
that lead to predictions of extrapolated field experiments
known to have improved accuracy,
and to demonstrate this by field measurements.
• This is a sensible goal because
– Our codes are almost entirely first-principles calculations
– Our approach will be to add physics not tuning
Page 16
Supplemental material follows
• More details
Page 17
People p. 1
CRASH Faculty
Where & what
UQ/ Predictive Capability
James Holloway, Co-PI, lead
UM Prof. Nuclear
Bruce Fryxell, chief scientist
UM AOSS Res. Sci.
Natasha Andronova
UM AOSS Res. Sci.
Krzysztof Fidkowski
UM Prof. Aero
Bani Mallick
TAMU Prof. Stats
Vijayan Nair
UM Prof. Stats & IOE
Derek Bingham
SFU Prof. Stats
Ji Zhu
UM Prof. Stats & IOE
Scientific Computing
Quentin Stout, Co-PI, lead
UM Prof. CSE
Nancy Amato
TAMU Prof. CompSci
Lawrence Rauchwerger
TAMU Prof. CompSci
Code Development, Testing, and UQ support
Ken Powell, Co-PI, lead
UM Prof. Aero
Gabor Toth, Software Archit.
UM AOSS Res. Sci.
Igor Sokolov
UM AOSS Res. Sci.
Bart van der Holst
UM AOSS Res. Sci.
Eric Myra
UM AOSS Res. Sci.
Modeling and Theory
Marv Adams, Co-PI
TAMU Prof. Nuclear
Ben Torralva
UM MSE Res. Sci.
Ed Larsen
UM Prof. Nuclear
Bill Martin
UM Prof. Nuclear
Ryan McClarren
TAMU Vis. Prof. Nuclear
Jim Morel
TAMU Prof. Nuclear
Bram van Leer
UM Prof. Aero
Phil Roe
UM Prof. Aero
Smadar Karni
UM Prof. Math
Katsuyo Thornton
UM Prof. MSE
Tamas Gombosi
UM Prof. Space Sci.
Experiments
Paul Drake, Director, lead
UM Prof. AOSS
Carolyn Kuranz
UM AOSS Res. Sci.
UQ/APC
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Experiments
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People p. 2
Grad Students
Advisor
Khieu, Loc
Miranda, Colin
Souza, Marcos
Zaide, Daniel
Chou, Jason
Doss, Forrest
Patterson, Nick
Huntington, Channing
Krauland, Christine
Visco, Tony
Cheatham, Jesse
Moran, Tiberus
Davidson, Greg
Baker, Eric
Zhang, Zhanyang
Di Stefano, Carlos
Gamboa, Eliseo
Young, Rachel
Starinshak, Dave
Mukherjee, Ashin
Barbu, Anthony
Edward, Jarrod
Prabhakar, Avinash
Van Leer
Fidkowsky and Powell
Powell
Powell and Roe
Fryxell and Drake
Drake
Thornton and Drake
Drake
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Holloway and Martin
Holloway
Larsen
Holloway and Martin
Nair/Zhu
Drake
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Karni and Fryxell
Nair/Zhu
Adams&Morel
Adams& Morel
Mallick
Mike Grosskopf
Donna Marion
Erica Rutter
Mauro Bianco
Duchwan Ryu
W. Daryl Hawkins
Sergey Manolov
Michael Adams
UM Sr. Res. Eng.
UM Technician/Target Fab
UM Technicican/ Codes
TAMU Post doc
TAMU Post doc
TAMU Softwr Architect
TAMU Staff programmer
TAMU Staff programmer
UQ/APC
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Administrative
Kathy Norris
Jan Beltran
UM CRASH Admin
UM Sr. Admin. Asst.
Page 19
Conservation of energy forces the shock wave to
develop complex structure
Shocked xenon layer
Compressed 40x
Traps thermal photons
Other fun
complications:
Instabilities
Wall shocks
Preheated region
Thermal photons
escape upstream
Page 20
Our experiments are at the Omega laser
One of our shots at the Omega laser
Related experiments
LULI & PALS & RAL, LIL (soon?)
NIF & LMJ maybe someday
Omega
60 beams
30 kJ in 1 ns
0.35 µm wavelength
Page 21
How to produce radiative shocks
Laser beams launch Be piston
into Xe or Ar gas at > 100 km/s
Piston drives shock
Gas filled tubes
Diagnostics measure plasma
properties
Gold grids provide spatial
reference
Parameters
1015 W/cm2
0.35 µm light
1 ns pulse
600 µm tube dia.
Targets: Korbie Killebrew, Mike Grosskopf,
Trisha Donajkowski, Donna Marion
Page 22
Experiments: Amy Reighard, Tony Visco, Forrest Doss
The laser first creates structure
at the target surface
• The laser is absorbed at less than 1% of solid
density
Ablation pressure
from momentum
balance:
p ~ 8.6 I142/3 / µm2/3 Mbars
Typical pressures of
tens of Mbars
From Drake, High-Energy-Density Physics, Springer (2006)
Radiative shocks need
thinner targets than the
one shown here
Page 23
For radiative shocks, target acceleration
produces the high required velocities
Acceleration pushes velocity
into radiative shock regime
• Profiles at 1.3 ns shown
Laser produced
pressure accelerates
Be plasma
Expanding Be drives
shock into Xe gas
Page 24
Researchers are studying these shocks with a
range of diagnostics and simulations
•
Radiographs
Emission
Interferometry
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Xray Thomson scattering
Data credits: L. Boireau S. Bouquet, F. Doss M.
Koenig, C. Michaut, A. Reighard, T. Visco , T. Vinci
Page 25
Radiography is our workhorse;
we also use other diagnostic methods
X-ray Thomson Transverse Streaked
Scattering
Optical Pyrometer (SOP)
Radiographs (1 or 2 views)
UV Thomson
Scattering
Data by grad students
Amy Reighard (Cooper),
Tony Visco, Forrest Doss,
Channing Huntington
Christine Krauland
Transverse VISAR
Page 26
Preliminary analysis of XRTS obtained reasonable
temperatures but a better model of Z is needed
Null Shot
•No drive beams, Null shot
•Zfree = .2
Data and fits by
Tony Visco
Precursor
•15ns delay
•Scattered from radiative
pre-heated region
•Fit gives Te = 10 eV &
Zfree = 12
Cooling Layer
•19ns delay
•Scattered from dense
cooling region
•Fit gives Te = 55 eV &
Zfree = 14
Page 27
Lateral structure within the shocked layer is
expected from a Vishniac-like mechanism.
See E. Vishinac,
ApJ 1983
Page 28
Theoretical analysis shows structure internal to
shocked layer for the experimental case
Perturbed system
Unperturbed system
Vorticity
features
Be
U
Z=H
.
Shocked
Xe
-Vs
Z=0
Vs
Unshocked Xe
• Wavelength and growth rate of instability in
Forrest Doss, et al.
reasonable agreement with observations
in preparation
• Stereoscopic experiments will seek further evidence
Page 29
Simulating these shocks is challenging but not
impossible
•
•
•
•
Optically thin, large upstream
Electron heating by ions
Optically thin cooling layer
Optically thick downstream
This problem has
• A large range of scales
• Non-isotropic radiation
• Complex hydro
20
Page 30
The CRASH project has evolved
over its first 18 months
Project status at day zero:
To do UQ, needed “reasonably good code” and experimental data
on variability and for calibration
Spring 2008
Funds arrive
Code planning
Recruiting
Summer 2008
CRASH 1.0 tasks
First sensitivity
Fall 2008
CRASH 1.0 beta
Expand UQ team
Variability Expt
Hire 2 FTE +
Winter 2009
CRASH 1.0 frozen
3D Yr5 simulation
UQ methods
exploration
Spr/Sum 2009
CRASH 2.0 Tasks
UQ on UQ
First end to end UQ
3rd hire (expts)
Fall 2009 expectation
CRASH 2.0 beta
3D CRASH sensitivity
Define 2D UQ study
Calibration experiment
Page 31