ISALE

From AMCGMedia

Fracturing (left) and compaction (right) surrounding a 20-cm diameter experimental crater in sandstone simulated using iSALE

iSALE

iSALE is a well-established, world-class tool for studying impacts, which has been used in pioneering studies of the formation of large impact craters on the Earth and the influence of target property variations on crater formation, the influence of a water layer on crater formation, as well as investigating the mobility of large rock avalanches.

iSALE includes advanced physics-based constitutive and porous-compaction models specifically designed for impact simulations. The porous-compaction model has been extensively validated against laboratory experiments and used to show, for the first time in numerical simulations, the important effect of friction and porosity on crater growth in granular materials.

A 3D version of iSALE is under development.

Technology

iSALE (impact-SALE) is a multi-material extension of the SALE hydrocode (Simplified Arbitrary Lagrangian Eulerian) developed primarily for the study of impact processes by Dr. Gareth Collins and international colleagues (Dr. Kai Wunnemann, Dr. Boris Ivanov and Prof. Jay Melosh).

Features

• Regular structured mesh
• Explicit finite-difference solution algorithm
• Artificial viscosity for shock capturing
• Multi-material advection scheme with PLIC interface reconstruction
• ANEOS and Tillotson equation of state routines
• Custom deviatoric strength model developed specifically for impacts in geologic materials
• An efficient porous compaction algorithm
• Fast and efficient output data read/write/compression algorithms

Validation

iSALE has been validated against several laboratory experiments and is being tested along with other hydrocodes as part of the Impact Hydrocode Benchmark and Validation Project. Model development and validation are ongoing, funded through separate projects, to ensure that iSALE remains a state-of-the-art tool in the study of impacts throughout the solar system.

Applications

iSALE has been used to study many aspects of impact cratering:

• The formation of several terrestrial impact craters
  • Chicxulub
  • Chesapeake Bay
  • Silverpit
  • Ries
  • Haughton
  • Sierra Madera
• The effect of porosity on crater growth
• Damage and deformation surrounding impact craters
• The head-on collision of porous planetesimals
• The effect of a water layer on crater formation
• Impact cratering on the icy satellites

Developers

iSALE is actively developed by AMCG members

• Dr. Gareth Collins
• Tom Davison

and by our partner research group at the Museum fur Naturkunde, Unversitat de Berlin

• Dr. Kai Wuennemann
• Dirk Elbeshausen

iSALE owes much of its sophistication to the pioneering early development of SALE by

• Dr. Boris Ivanov
• Prof. Jay Melosh

Publications

1. Collins, G.S., Kenkmann, T., Wunnemann, K. and Osinski, G. R. 2008. Mid-sized complex crater formation in mixed crystalline targets: Insight from modeling and observation. Meteoritics and Planetary Science. 43(12): 1955-1978.
2. Bray, V.J., Collins, G.S., Morgan, J.V. and Schenk, P.M. 2008. The effect of target properties on crater morphology: Comparison of central peak craters on the Moon and Ganymede. Meteoritics and Planetary Science, 43(12): 1979-1992.
3. Osinski, G.R., Grieve, R.A.F., Collins, G.S., Marion, C. and Sylvester, P. 2008. The effect of target lithology on the products of impact melting. Meteoritics and Planetary Science 43(12): 1939:1954.
4. Pierazzo E., Artemieva N., Asphaug E., Baldwin E.C., Cazamias J., Coker R., Collins G.S., Crawford D.A., Davison T., Elbeshausen D., Holsapple K.A., Housen K.R., Korycansky D.G., Wünnemann K. 2008. Validation of numerical codes for impact and explosion cratering, Meteoritics and Planetary Science. 43(12): 1917-1938.
5. Collins GS, Morgan J, Barton P, Christeson GL, Gulick S, Urrutia J, Warner M and Wunnemann K, 2008, Dynamic modeling suggests terrace zone asymmetry in the Chicxulub crater is caused by target heterogeneity, Earth and Planetary Science Letters doi:10.1016/j.epsl.2008.03.032
6. Wunnemann K, Collins GS, Osinski GR, 2008, Numerical modelling of impact melt production in porous rocks, Earth and Planetary Science Letters doi:10.1016/j.epsl.2008.03.007
7. Davison T, Collins GS, 2007, The effect of the oceans on the terrestrial crater size-frequency distribution: Insight from numerical modeling, Meteoritics and Planetary Science, 42(11): .
8. Goldin TJ, Wunnemann K, Melosh HJ, Collins GS, Hydrocode modeling of the Sierra Madera impact structure, METEORIT PLANET SCI, 2006, Vol: 41, Pages: 1947 - 1958, ISSN: 1086-9379
9. Collins, GS, Wunnemann, K, How big was the Chesapeake Bay impact? Insight from numerical modeling, GEOLOGY, 2005, Vol: 33, Pages: 925 - 928, ISSN: 0091-7613
10. Collins, GS, Melosh, HJ, Ivanov, BA, Modeling damage and deformation in impact simulations, METEORIT PLANET SCI, 2004, Vol: 39, Pages: 217 - 231, ISSN: 1086-9379
11. Pierazzo E, Collins G, A brief introduction to hydrocode modeling of impact cratering, In: Dypvik,D., Burchell,M., Claeys,P., editor, Cratering in marine environments and on ice, New York, Springer, 2004, Pages: 323 - 340, ISBN: 3-5404-0668-9
12. Collins GS, Melosh HJ, Morgan JV, et al, Hydrocode Simulations of Chicxulub crater collapse and peak-ring formation, ICARUS, 2002, Vol: 157, Pages: 24 - 33, ISSN: 0019-1035
13. Collins GS, Melosh HJ, Acoustic fluidization and the extraordinary mobility of sturzstroms, J GEOPHYS RES-SOL EA, 2003, Vol: 108