NERSC Initiative for Scientific Exploration (NISE) 2010 Awards

Warm Dense Matter simulations using the ALE-AMR code

Enrique Henestroza, Berkeley Lab

Associated NERSC Project: Simulation of intense beams for heavy-ion-fusion science (mp42), Principal Investigator: Alex Friedman, Berkeley Lab

Simulations of the poorly understood regime of Warm Dense Matter (WDM) are important in designing experiments at the planned Neutralized Drift Compression Experiment II (NDCX-II) facility. This regime is found naturally in, e.g., the interiors of giant planets. In terrestrial settings it generally appears transiently, e.g., in the early stages of inertial-fusion experiments. As a subset of High Energy Density Physics, WDM is the subject of considerable emerging interest both as basic science and for its importance to inertial-fusion power production.

We propose to model WDM experiments using the ALE-AMR code and to incorporate new physics into the code, specifically a surface tension model, in order to make the code better suited for NDCX-II, which is under construction with completion planned for 2012. It will be very important to have suitable computational models for comparing with experimental results. ALE-AMR is the most capable code platform for such studies, and has proven itself on a range of applications, including studies of damage to NIF target supports and the basic physics of multiscale flows. A surface tension model is needed before the code can reliably model the full spectrum of planned experiments on the new facility and the existing NDCX-I facility. However, simulations of WDM can be done now, to test the code's existing physics models (e.g., ion deposition) for this new application area, while we develop the surface tension model.

In the proposed research, we will examine a family of emerging approaches to surface tension modeling, with an eye toward selecting an approach that scales well to tens of thousands of processors. This is somewhat challenging since surface tension is not an entirely local effect: the curvature and topology of the surface come into play. However, we believe that preserving quasi-locality will be sufficient for both the physics and the required computational efficiency.

We will use the NISE allocation to enable the development of the required scalable models, and to simulate both planned experiments on and synthetic diagnostic results from NDCX-II. This will position us so that we are able to properly plan and analyze actual experiments when NDCX-II becomes available, thereby significantly enlarging the value of DOE's investment in the new facility.