A Case Study in the Visualization of Supernova Simulation Data Ed Bachta Visualization and...
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Transcript of A Case Study in the Visualization of Supernova Simulation Data Ed Bachta Visualization and...
A Case Study in the Visualization of Supernova Simulation Data
Ed Bachta
Visualization and Interactive Spaces Lab
Overview
Introduction Lagrangian-Eulerian Advection Software Design Results Future Work
A Core-collapse Supernova
Begins with a star of 8+ solar masses Eventually, fusion produces Fe in the core Pressure from fusion loses to gravitation Material falls inward, increasing density Neutrinos radiated at a rate of 1057 /s Strong force halts collapse Remaining material rebounds off the core Shock wave carries material away from the core
Simulation
Doug Swesty & Eric Myra, SUNY Stony Brook Exploring the role of convection Radiation hydro code scales to 1000s of procs 2 spatial dimensions (soon to be extended to 3) 20 groups of neutrinos at different energies
Lagrangian-Eulerian Advection A process for visualizing vector
fields, valid for unsteady flows Noise is advected along the
flow, generating an image as output
Results Single frames portray
instantaneous flow Animations simulate motion of
material in flow
Vector plot LEA
“Lagrangian-Eulerian Advection for Unsteady Flow Visualizaion”
Particles seeded randomly each iteration Backward integration finds upstream cell Color of upstream cell advected forward Results blended temporally with bias toward most recent Jobard, Erlebacher, Hussaini (IEEE Vis & CG 2002 [8:3])
Noise at t-1
v
Lagrangianstep
Eulerianstep
LEA Animated
Applied to velocity Propagation of light and
dark areas indicates direction of flow
Areas where noise remains have near-zero velocities
Software
Vis modules provided by the Visualization Tool Kit (VTK)
LEA filter for VTK developed at the Swiss National Supercomputing Centre
Scripts programmed in Python
Results
Combination of LEA with: Scalar data representations
Via colormaps Via iso-contours
Vector data comparisons Via visualization of dot products
LEA & Scalars
Velocity & Entropy
Shows the development of regions of high entropy in upper convective zones
LEA & Iso-Contours
LEA & Optical Depth
The iso-contour where optical depth = 1 describes the surface of last scattering
Generated for each energy group Our results show that these
contours vary with energy group and evolve along with the shock
12
3
8
LEA & Dot Products
Advective vs. Radiative NeutrinoFlux Radiative neutrino flux
Tendency to propagate outward
Advective neutrino flux Effect of convection
Dot product indicates: “Constructive” flux “Destructive” flux Orthogonal flux
Comparison Over Energy
Comparison of Gradients
Lagrangian multipliers: ∂rf (r) = λ ∂rg(r) Describes a set of points where the iso-contours of f(r)
and g(r) are tangential A positive λ indicates parallel gradients A negative λ indicates anti-parallel gradients Very similar to our dot product analysis
The dot product reveals orthogonal conditions
Entropy & Temp.
Using our visualization scheme, we can see: Where the gradients are || Where they are anti-|| Where they are orthogonal How this relates to the flow
of a vector field
Future Work
Extending the framework to support iteration Developing new visualization techniques Enabling remote visualization
Intended for batch processing Investigating Web Services