GPUs TO MARS Full Scale Simulation of SpaceXs Mars Rocket Engine - PowerPoint PPT Presentation

GPUs TO MARS Full Scale Simulation of SpaceX’s Mars Rocket Engine Adam Lichtl, Stephen Jones, GTC 2015

Background  Independent space launch company  Build and operate our own rocket & capsule  Operations in CA, TX & FL  Founded in 2002, first launch in 2008  18 successful missions to date

Design

Build

Launch

Mars Length of day 24 hours, 40 minutes Length of year 687 days Gravity 0.375g s Distance from Sun 1.53 AU Mars Air CO 2 (96%), N 2 (2%) Earth Air O2 (21%), N2 (78%) Atmosphere 1% density / pressure of Earth Temperature -284 / +86 / -81 F (low / high / avg)

Human Mars Mission Classes Credit: CollectSpace

Mass to Mars Apollo Command & International Space Station NASA Mars Architecture Service Module   Mass: 450 tons Mass: 300 tons    Mass: 46 tons 36x Space Shuttle, 3x heavy-lift  Terrestrial assembly 5x Proton launches launches  In-orbit assembly Image Credit: NASA Image Credit: NASA Image Credit: Mark Benson & Kerbal Space Program

Methane Fuel Carbon dioxide from atmosphere Synthesize return-journey fuel on Mars O C O C O 2H 2 O + CO 2 -> CH 4 + 2O 2 O O H H C O O H H O H O Water from below ground O H H H

Rocket Engine Design

Why Simulation? 1. Investigate what cannot be measured 2. Reduce need for testing 3. Design optimisation: narrow design space 4. Proactive instead of reactionary design

Time scales vary by 8 orders of magnitude Diffusion Advection Acoustics 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 seconds Reaction Chamber Residence

Length scales vary by Injection 6 orders of magnitude log E(k) Cascade Combustion Eddy Energy Chamber: ~1m Kolmogorov Scale: ~1µm Viscous dissipation k min k max Eddy Wavenumber Total points: (10 3 ) 6 = 10 18 = 1,000,000,000,000,000,000 points @1kB per point -> Yottabytes of data

Structure in Turbulence Credit: SpaceWeather

Simulation Meshing Structured Grid Adaptive Grid Unstructured Grid

Fourier Transform: Spectral Compression

Wavelets: Local Fractal Basis

Wavelet Compression

Wavelet Compression

Wavelet Compression

Wavelet Compression

Wavelet Compression δ δ δ < ε δ > ε ( ε is some tolerance)

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Wavelet Compression Transform Output

Decompression Transform Output

Decompression Transform Output

Decompression Transform Output

Decompression + δ Transform Output

Decompression Transform Output

Decompression Transform Output

Decompression Transform Output

Decompression Transform Output

Decompression Transform Output

Regular Grid: Direct Indexing (x, y, z) (x, y+1, z) Index (x, y, z) = p Index (x, y+1, z) = p + N x

Sparse Grid: Difficult Indexing (x, y, z) (x, y+1, z) Index (x, y, z) = p Index (x, y+1, z) = ???

Sparse Grid Point Lookup Linear search Tree-based search Hybrid tree search + dense indexing

Grid Point Contains Reference to Data Grid Point 14 Location (x,y,z) Data Reference (x, y, z)

Grid Point Contains Reference to Data Grid Point 14 15 Grid Index 14 16 Location (x,y,z) (11,11,5) (11,12,5) (Location) Grid Data Data Reference 3 8 (Reference) (x, y, z)

Grid Point Contains Reference to Data Grid Point 14 15 Grid Index 14 16 Location (x,y,z) (11,11,5) (11,12,5) … Grid Data Data Reference 3 8 … ρ 0 ρ 1 ρ 2 ρ 3 ρ 4 ρ 5 ρ 6 ρ 7 ρ 8 ρ 9 density (x, y, z) ρ u 0 ρ u 1 ρ u 2 ρ u 3 ρ u 4 ρ u 5 ρ u 6 ρ u 7 ρ u 8 ρ u 9 X-momentum ρ v 0 ρ v 1 ρ v 2 ρ v 3 ρ v 4 ρ v 5 ρ v 6 ρ v 7 ρ v 8 ρ v 9 Y-momentum ρ w 0 ρ w 1 ρ w 2 ρ w 3 ρ w 4 ρ w 5 ρ w 6 ρ w 7 ρ w 8 ρ w 9 Z-Momentum E 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7 E 8 E 9 Energy Simulation Data

Grid Point Contains Reference to Data Grid Point 14 15 Grid Index 14 16 Location (x,y,z) (11,11,5) (11,12,5) … Grid Data Data Reference 3 8 … ρ 0 ρ 1 ρ 2 ρ 3 ρ 4 ρ 5 ρ 6 ρ 7 ρ 8 ρ 9 density (x, y, z) ρ u 0 ρ u 1 ρ u 2 ρ u 3 ρ u 4 ρ u 5 ρ u 6 ρ u 7 ρ u 8 ρ u 9 X-momentum ρ v 0 ρ v 1 ρ v 2 ρ v 3 ρ v 4 ρ v 5 ρ v 6 ρ v 7 ρ v 8 ρ v 9 Y-momentum ρ w 0 ρ w 1 ρ w 2 ρ w 3 ρ w 4 ρ w 5 ρ w 6 ρ w 7 ρ w 8 ρ w 9 Z-Momentum E 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7 E 8 E 9 Energy Simulation Data

Grid Adaptation Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9

Grid Adaptation Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9

Grid Adaptation Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9

Grid Adaptation Grid Index P 0 P 2 P 4 P 6 P 8 Location x 0 y 0 x 2 y 2 x 4 y 4 x 6 y 6 x 8 y 8 Reference 0 2 4 6 8

Grid Adaptation Grid Index P 0 P 1 P 2 P 3 P 4 Location x 0 y 0 x 2 y 2 x 4 y 4 x 6 y 6 x 8 y 8 Reference 0 2 4 6 8

Grid Transformations Track Data Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9

Grid Transformations Track Data Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9 Delete Add Sort Transpose

Grid Transformations Track Data Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 0 y 0 x 1 y 1 x 2 y 2 x 3 y 3 x 4 y 4 x 5 y 5 x 6 y 6 x 7 y 7 x 8 y 8 x 9 y 9 Reference 0 1 2 3 4 5 6 7 8 9 Delete Add Sort Transpose Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 4 y 4 x 7 y 7 x 9 y 9 x 0 y 0 x 5 y 5 x 1 y 1 x 8 y 8 x 3 y 3 x 6 y 6 x 2 y 2 Reference 4 7 9 0 5 1 8 3 6 2

Losing Coalesced Memory Access Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Reference 0 1 2 3 4 5 6 7 8 9 ρ 0 ρ 1 ρ 2 ρ 3 ρ 4 ρ 5 ρ 6 ρ 7 ρ 8 ρ 9 ρ u 0 ρ u 1 ρ u 2 ρ u 3 ρ u 4 ρ u 5 ρ u 6 ρ u 7 ρ u 8 ρ u 9 ρ v 0 ρ v 1 ρ v 2 ρ v 3 ρ v 4 ρ v 5 ρ v 6 ρ v 7 ρ v 8 ρ v 9 ρ w 0 ρ w 1 ρ w 2 ρ w 3 ρ w 4 ρ w 5 ρ w 6 ρ w 7 ρ w 8 ρ w 9 E 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7 E 8 E 9 Coalesced Simulation Data

Losing Coalesced Memory Access Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Reference 4 7 9 0 5 1 8 3 6 2 ρ 0 ρ 1 ρ 2 ρ 3 ρ 4 ρ 5 ρ 6 ρ 7 ρ 8 ρ 9 ρ u 0 ρ u 1 ρ u 2 ρ u 3 ρ u 4 ρ u 5 ρ u 6 ρ u 7 ρ u 8 ρ u 9 ρ v 0 ρ v 1 ρ v 2 ρ v 3 ρ v 4 ρ v 5 ρ v 6 ρ v 7 ρ v 8 ρ v 9 ρ w 0 ρ w 1 ρ w 2 ρ w 3 ρ w 4 ρ w 5 ρ w 6 ρ w 7 ρ w 8 ρ w 9 E 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7 E 8 E 9 Uncoalesced Simulation Data

Restoring Coalesced Memory Access Grid Index P 0 P 1 P 2 P 3 P 4 P 5 P 6 P 7 P 8 P 9 Location x 4 y 4 x 7 y 7 x 9 y 9 x 0 y 0 x 5 y 5 x 1 y 1 x 8 y 8 x 3 y 3 x 6 y 6 x 2 y 2 Reference 4 7 9 0 5 1 8 3 6 2 ρ 0 ρ 1 ρ 2 ρ 3 ρ 4 ρ 5 ρ 6 ρ 7 ρ 8 ρ 9 ρ u 0 ρ u 1 ρ u 2 ρ u 3 ρ u 4 ρ u 5 ρ u 6 ρ u 7 ρ u 8 ρ u 9 ρ v 0 ρ v 1 ρ v 2 ρ v 3 ρ v 4 ρ v 5 ρ v 6 ρ v 7 ρ v 8 ρ v 9 ρ w 0 ρ w 1 ρ w 2 ρ w 3 ρ w 4 ρ w 5 ρ w 6 ρ w 7 ρ w 8 ρ w 9 E 0 E 1 E 2 E 3 E 4 E 5 E 6 E 7 E 8 E 9 Uncoalesced Simulation Data