# Presentation: 925265

## www.sandia.gov/NNSA/russia/

**Russian****Collaborations**

## Oleg SchillingLawrence Livermore National LaboratoryASC Principal Investigators Meeting26 February, Monterey, CA

**Oleg Schilling****Lawrence Livermore National Laboratory****ASC Principal Investigators Meeting****26 February, Monterey, CA**

- Overview of Collaborations Between LLNL and Russian Federation Institutes

**This work was performed under the auspices of the U.S. Department of Energy by ****Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344**

**LLNL-PRES-401247**

**Zababakhin Scientific Talks, Snezhinsk 2007**

## LLNL maintains a portfolio of collaborations with the RF in computational and material science

- We are broadly engaging scientists at our counterpart Laboratories (VNIIEF, Sarov and VNIITF, Snezhinsk)
- Over the years we have executed projects involving simulations, experiments, and theory
- Simulation projects of interest to ASC include
- Hybrid Structured/Unstructured Mesh Hydrodynamics and Heat Conduction (VNIIEF)
- Refinement/Reconnection in Free-Lagrange Simulations (VNIIEF)
- Development/Study of Adaptive Energy/Angle Variables for Solving Transport Equations (VNIIEF)
- Quantum Mechanical Simulation of Actinides (VNIITF)
- MD Simulation of Elastic-Plastic and Spall Mechanisms in Dynamically Loaded Cu (VNIITF)
- Analytical Solutions to Test Codes Simulating Gas Dynamics and Radiation Transport (VNIITF)

**grain boundary**

**shock**

## An experimental/computational collaboration with VNIIEF has improved constitutive models

- Data from shocked/shockless loading of Al, Cu and V with perturbations at strain-rates 104-106 s-1
- Measure influence of dynamic strength on instability growth  for code/strength model V & V
- Simulations provided confidence in the SG and   PTW strength models

**Detonator**
**High explosive**
**Vacuum Gap**
**Liner**
**Sealing cylinder**

**Liner with imposed perturbations**

**Rayleigh********Taylor instability growth diagnosed by**
**side-on radiography**

**ARES simulation**

**Pressure field from simulation**

## A computational collaboration with VNIIEF is exploring more efficient adaptive algorithms for transport

- Discretizing *S**N* transport equation
-    in space, direction, and frequency requires *N**x **N**y **N**z **N**** **N**** **N*** variables  (109-12 variables in 3D)
- Adaption in angle or energy can potentially accelerate and improve transport algorithms

**Insufficient angular resolution + geometric divergence = ray effects**

**Flux from slit test problem with 8, 16, 100 angles and 8 angles with 1****st****- and 4****th****-order adaptivity**

## Collaborations with the Russian Federation can benefit the Laboratory and ASC

- Algorithm development, computational material science, and test problem projects can positively impact the Program
- Simulation collaborations provide testbeds for *developing and exploring more efficient methods for transport and hydrodynamics*
- Synergistic collaboration in experimental and computational material science can *advance physical, constitutive, and multi-scale modeling* * *
- Test problem collaborations can* add new problems to the V&V suite*
- Our collaborators have pursued computational science in parallel with us
- The Laboratories can potentially benefit from their novel approaches

##  Marvin A. Zocher, Robert E. Reinovsky, James R. Kamm,Michael F. StevensASCI PI Meeting, Monterey, CAFeb 26, 2008

- Overview of LANL Participation in the US/Russian S&T Collaborations

***Snezhinsk City Square***

***Sarov Bell Tower***

## TO 21 (VNIIEF): Ignatova
Constitutive Behavior and Damage Mechanics

- Constitutive Behavior and Damage Mechanics

- Experimental/Theoretical/Numerical collaboration
- Leading to better constitutive and damage models

- Grain Size Effects
- Localization Effects
- Temporal Softening
- Scaling Effects

- SCCM 2007, p. 597, p. 649

## TO 9 (VNIITF): Dremov
Molecular Dynamics Studies: Shock-Induced Microstructure Evolution, Pu Aging

- TO 9 (VNIITF): Dremov
- Molecular Dynamics Studies: Shock-Induced Microstructure Evolution, Pu Aging

- Initiation and
- 	Evolution of Damage
- 	Phys Rev B, Vol 74, No. 14, 2006

- DFT, MD simulations: leading to better understanding of Pu Aging

- He diffusion
- He bubble formation
- Bubble-bubble interaction
- Self-irradiation damage in Pu lattice already containing He and bubbles
- He bubble diffusion
- He bubble stability

- Submitted to Phys Rev

## TO 35 (EF) Zhernokletov, TO 10 (TF) Petrovtsev
Cerium

- TO 35 (EF) Zhernokletov, TO 10 (TF) Petrovtsev
- Cerium

- Experimental/Theoretical/Numerical collaboration
- Leading to better understanding of phase
- mechanics, phase change kinetics, multiphase models

- Ce is an interesting material:

- Complex Phase Diagram
- Four solid phases at zero pressure; at least 3 more at pressure > 0
- -phase has negative bulk modulus
- Solid-solid critical point
- Large volume collapse (~15%) on - transition
- Large regions of phase diagram uncertain
- Anomalous melting at low pressure
- Complex electronic behavior

- SCCM 2007, p. 105, p. 117

## TO 24 (VNIIEF): Boyko
Damage Mechanisms in Cylindrically Convergent Geometry

- TO 24 (VNIIEF): Boyko
- Damage Mechanisms in Cylindrically Convergent Geometry

- Experimental/Theoretical/Numerical collaboration
- employing a unique driver developed by VNIIEF
- aimed at gaining a better understanding of
- post-damage recollection and recompression

- Magnetic (pulsed power) driven cylindrical
- implosions provide both highly precise
- shock-induced damage AND sufficient
- reacceleration of the “damaged” surface to
- overtake and recollect damaged material
- Valuable date on damage initiation and
- evolution including recollection and
- recompaction for the
- development/evaluation of improved
- damage models
- Six of ten planned experiments complete

## Summary 

- LANL has had ongoing involvement for more that 15 years
- The collaboration has proven to be highly valuable: providing
- unique experimental data, unique models, unique numerical
- methods, unique problem approaches, access and insight, etc.

- Metrics for Success:
- Collaborations are characterized by comparable levels of effort by both Russian and American researchers
- Collaborations are of mutual interest: focused on research topics that enhance/support/complement the research objectives of both sides
- Collaborations are characterized by parity: projects are chosen by mutual consent and the overall commitment of each side is comparable
- Collaborations are of high scientific merit: the work stands the test of peer review and generates appropriate outputs such as publications, conference presentations, and other archival value documents, etc., as appropriate

- How are we doing?
- At present, metrics 2 and 4 are satisfactorily being met; metrics 1 and 3 are,
-  in general, not being met.

##  Heath L. Hanshaw, John B. AidunSandia National Laboratories  ASC PI Meeting, Monterey CA 26 February 2008

*SNL ASC Science & Technology Collaborations with Russian Federal Nuclear Centers  **and Russia Academy of Science Institutes*

- SAND08-0982C

- Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

##  SNL is engaged with 9 PIs at 5 institutions in research in computer science, HEDP, and computational materials:
 Federal Nuclear Centers: VNIIEF (Sarov); VNIITF (Snezhinsk); VNIIA (Moscow).
 Academy of Science Institutes: JIHT (Moscow);  IPME (St. Petersburg).
 Benefits of these collaborations:
Alternative approaches to problems;
Access to world-class experts in areas of NNSA interest;
Access to unique and valuable technology; 
Technical advances.

-  Federal Nuclear Centers: VNIIEF (Sarov); VNIITF (Snezhinsk); VNIIA (Moscow).
-  Academy of Science Institutes: JIHT (Moscow);  IPME (St. Petersburg).
-  Benefits of these collaborations:
- Alternative approaches to problems;
- Access to world-class experts in areas of NNSA interest;
- Access to unique and valuable technology;
- Technical advances.

- Sandia staff are leveraging Russian colleagues’ expertise to advance ASC project objectives

## 6 SNL-Russia projects cover topics ofComputer Science and HEDP

-  Computer Science [N. Pundit w/ ITMF/VNIIEF]:
- Scalability of parallel algorithms;
- Interconnect effects on code scalability;
- Supercomputer efficiency with timing instabilities.
-  HEDP & Pulsed Power: [H. Hanshaw]
- MHD simulation of Z- and Z- pinches (VNIIEF);
- Simulation of wire array implosions (VNIITF);
- Hybrid code for PetaWatt laser/dense plasma interaction (VNIITF).

**Notes:**
> In the 1st project is developing accurate and predictable mathematical models for assessing how algorithms will run on Petaflops-class supercomputers, especially in the presence of faulty processors or missing nodes. 
> The 2nd project is developing models of simulation code performance on future supercomputers, with specific emphasis on the effects of inter-processor communications.  This study will contribute to understanding how well simulation codes will scale up to run on very large supercomputers.  This project is coordinated with the 1st project. 
> The 3rd project is developing a program to measure and report timing instabilities on parallel computers. Unequal CPU speeds, unequal memory speeds, operating system noise, and message contention on processor interconnects all produce timing instabilities that diminish supercomputer efficiency. 
HEDP:
Project is validating 2D and 3D resistive MHD models of Z-pinch experiments performed at SNL.  The models make alternate choices to those made at SNL.
VNIITF is using its HEDP codes.  These incorporate kinetic effects thru hybrid models and use higher order Eulerian adaptive meshes.  Exploring impact of a variety of physics and modeling choices on wire array physics and moving toward the predictive models needed for design of pulsed power machines and experiements on them.
VNIITF is completing development of adaptive mesh refinement in their 2D hybrid PIC code and applying it to simulate the interaction of a short pulse PW laser with dense plasmas for cases of interest, like fast ignition.

## 6 SNL-Russia projects cover topics inComputational Materials

- MD study of phonon generation during cracking
- E.P. Chen w/ ITMF/VNIIEF;
- Platform-independent molecular builder & visualizer
- J.Aidun w/ ITMF/VNIIEF;
- Modeling thermal decomposition of polymeric materials
- K. Erickson w/ VNIIA;
- MD study of phonon generation by laser excitation
- E.P.Chen w/ IPME;
- Performance & reliability of MEMS
- E.P.Chen w/ IPME;
- Extending non-equilibrium MD methods
- A.Thompson w/ JIHT;

**Notes:**
Phonon generation is inherent during cracking and is thought to influence crack propagation, but it is completely beyond the considerations of continuum mechanics.
Building on recent work at Sarov Labs, a Unix/Linux based pre- and post-processor for atomistic simulations was developed to enable studies of crystal defects, grain boundaries, and material interfaces.  Follow-on work is applying the MBV in MD simulations of energetic molecular crystals using Sandia’s LAMMPS code.
A computational model for polymers is being developed based on thermal decomposition measurements made at VNIIA’s unique experimental facility.  Relevant to weapon safety in abnormal environments.
The project is motivated by the need for accurate, sub-continuum characterization of energy transport following brief laser irradiation for fracture prediction and for evaluating the performance of MEMS devices that incorporate lasers.  Laboratory measurement of heat transport following laser irradiation will be performed for discovery and simulation validation.
This project is investigating factors that affect the performance and lifetime of MEMS from two perspectives: 1) creep and recrystallization in low-cycle, thermally activated devices; 2) fatigue in high-cycle devices.  A variety of mechanics theory and numerical modeling methods are being applied in the studies.
Novel non-equilibrium MD methods are being extended and applied in four areas of interest: 1) equilibration of non-ideal plasmas; 2) melting in superheated material; 3) classical potentials for simulating chemistry (bond formation and breaking); 4) mechanisms of shock-induced plasticity and fracture in metals.  The work will enhance our understanding and capabilities for investigating the dynamic response of multiple types and states of materials. 

## SNL-Russia Project Highlights 

- G.E.Norman (JIHT) invited to talk at SCCM07: “*Atomistic simulation of plasticity, spall damage and fracture of crystalline and polycrystalline metals u**nder high strain rate*.”
- Providing insights on dynamic strength and damage.
- VNIIA-Mendeleyev U.-VNIIPO-SNL joint paper: “Thermal Decomposition Mechanism of PMDI-Based Polyurethane Foam Studied by Multiple Methods,” submitted to *J. Polymer Degradation and Stability*
- Unique experimental capability and expertise advancing the science of foam decomposition.
- VNIIEF Comp.Sci. researchers’ analytical model successfully predicts operating system noise effects on the scale of parallelism.
- Laying the groundwork for ever larger scale parallelism.
- VNIITF hybrid PIC MHD code reveals importance of kinetic effects in the evolution of thermal instabilities in Z-Pinches.
- Access to alternative modeling approaches speeds discovery.

**Notes:**
1. Prof. Norman’s talk was followed by 3 talks by his colleagues:
“Atomistic simulations of fracture in nanocrystalline copper under high strain rates,” A. Yanilkin, A. Kuksin, G. Norman, V. Stegailov
“Modeling of Al crystal fracture under high-rate strain based on atomistic simulations,” A. Kuksin, G. Norman,  V. Stegailov,  A. Yanilkin 
“Atomistic study of nanoprecipitates influence on plasticity and fracture of crystalline metals,” V. Stegailov,  A. Kuksin,  G. Norman,  A. YanilkinThe work and travel were partially funded under contract with Sandia.
2. The paper reports the results of experiments on thermal decomposition of foam performed at the unique, very high rate heating facility at VNIIA and analyses and modeling of those experiments. 
V. S. Sirenko(a, R. A. Kozlovskiy(b, Yu. K. Naganovsky(c, E. I. Popova(a, S. A. Mulyashov(b, and K. L. Erickson(d.
a VNIIA; b D.Mendeleyev University of Chemical Technology of Russia; c All Russian Research Institute of Fire Safety (VNIIPO); d SNL.
3. As we move towards ExaFLOPS computing, operating system (OS) noise will be critical for application code scaling and performance.  OS noise is a concern in current OS development work at SNL and Cray.
4. VNIITF colleagues developed a particle-in-cell (PIC) MHD code that implements a hybrid of physics phenomena.  The code is eulerian with automatic mesh refinement (AMR).  This combination of capabilities and physics distinguish the code from those at SNL.  It is of interest to learn the strengths and relative value of these alternate approaches and identify capabilities worth adding to Tri-lab codes.