scholarly journals A diffuse interface method for solid-phase modeling of regression behavior in solid composite propellants

2021 ◽  
Author(s):  
Baburaj Kanagarajan ◽  
J. Matt Quinlan ◽  
Brandon Runnels
Keyword(s):  
Phase Field ◽  
Adaptive Mesh Refinement ◽  
Solid Phase ◽  
Morphological Changes ◽  
Adaptive Mesh ◽  
Quantitative Agreement ◽  
Design Tool ◽  
Diffuse Interface ◽  
Solid Composite Propellants ◽  
Structured Adaptive Mesh Refinement

Solid composite propellants (SCPs) are ubiquitous in the field of propulsion. In order to design and control solid SCP rocket motors, it is critical to understand and accurately predict SCP regression. Regression of the burn surface is a complex process resulting from thermo-chemical-mechanical interactions, often exhibitingextreme morphological changes and topological transitions. Diffuse interface methods, such as phase field (PF), are well-suited for modeling processes of this type, and offer some distinct numerical advantages over their sharp-interface counterparts. In this work, we present a phase-field framework for modelingthe regression of SCPs with varying species and geometry. We construct the model from a thermodynamic perspective, leaving the base formulation general. A diffuse-species-interface field is employed as a mechanism for capturing complex burn chemistry in a reduced-order fashion, making it possible to model regressionfrom the solid phase only. The computational implementation, which uses block-structured adaptive mesh refinement and temporal substepping for increased performance, is briefly discussed. The model is then applied to four test cases: (i) pure AP monopropellant, (ii) AP/PBAN sandwich, (iii) AP/HTPB sandwich,and (iv) spherical AP particles packed in HTPB matrix. In all cases, reasonable quantitative agreement is observed, even when the model is applied predictively (i.e., no parameter adjustment), as in the case of (iv). The validation of the proposed PF model demonstrates its efficacy as a numerical design tool for future SCP investigation.

scholarly journals AMReX: Block-structured adaptive mesh refinement for multiphysics applications

2021 ◽  
pp. 109434202110228
Author(s):  
Weiqun Zhang ◽  
Andrew Myers ◽  
Kevin Gott ◽  
Ann Almgren ◽  
John Bell
Keyword(s):  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Computational Cost ◽  
Adaptive Mesh ◽  
Uniform Mesh ◽  
Physical Processes ◽  
Structured Adaptive Mesh Refinement ◽  
Core Elements ◽  
Accelerator Design ◽  
Block Structured

Block-structured adaptive mesh refinement (AMR) provides the basis for the temporal and spatial discretization strategy for a number of Exascale Computing Project applications in the areas of accelerator design, additive manufacturing, astrophysics, combustion, cosmology, multiphase flow, and wind plant modeling. AMReX is a software framework that provides a unified infrastructure with the functionality needed for these and other AMR applications to be able to effectively and efficiently utilize machines from laptops to exascale architectures. AMR reduces the computational cost and memory footprint compared to a uniform mesh while preserving accurate descriptions of different physical processes in complex multiphysics algorithms. AMReX supports algorithms that solve systems of partial differential equations in simple or complex geometries and those that use particles and/or particle–mesh operations to represent component physical processes. In this article, we will discuss the core elements of the AMReX framework such as data containers and iterators as well as several specialized operations to meet the needs of the application projects. In addition, we will highlight the strategy that the AMReX team is pursuing to achieve highly performant code across a range of accelerator-based architectures for a variety of different applications.

3-Dimensional Hybrid Continuum-Atomistic Simulations for Multiscale Hydrodynamics

2003 ◽  
Author(s):  
H. S. Wijesinghe ◽  
R. Hornung ◽  
A. L. Garcia ◽  
N. G. Hadjiconstantinou
Keyword(s):  
Adaptive Mesh Refinement ◽  
Hybrid Methods ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Scale Model ◽  
Structured Adaptive Mesh Refinement ◽  
Flow Gradients ◽  
The Continuum

We present an adaptive mesh and algorithmic refinement (AMAR) scheme for modeling multi-scale hydrodynamics. The AMAR approach extends standard conservative adaptive mesh refinement (AMR) algorithms by providing a robust flux-based method for coupling an atomistic fluid representation to a continuum model. The atomistic model is applied locally in regions where the continuum description is invalid or inaccurate, such as near strong flow gradients and at fluid interfaces, or when the continuum grid is refined to the molecular scale. The need for such “hybrid” methods arises from the fact that hydrodynamics modeled by continuum representations are often under-resolved or inaccurate while solutions generated using molecular resolution globally are not feasible. In the implementation described herein, Direct Simulation Monte Carlo (DSMC) provides an atomistic description of the flow and the compressible two-fluid Euler equations serve as our continuum-scale model. The AMR methodology provides local grid refinement while the algorithm refinement feature allows the transition to DSMC where needed. The continuum and atomistic representations are coupled by matching fluxes at the continuum-atomistic interfaces and by proper averaging and interpolation of data between scales. Our AMAR application code is implemented in C++ and is built upon the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) framework developed at Lawrence Livermore National Laboratory. SAMRAI provides the parallel adaptive gridding algorithm and enables the coupling between the continuum and atomistic methods.

scholarly journals Dynamic Load Balancing of Samr Applications on Distributed Systems

2002 ◽  
Vol 10 (4) ◽  
pp. 319-328 ◽  
Author(s):  
Zhiling Lan ◽  
Valerie E. Taylor ◽  
Greg Bryan
Keyword(s):  
Distributed Systems ◽  
Load Balancing ◽  
Dynamic Load ◽  
Adaptive Mesh Refinement ◽  
Heuristic Method ◽  
Adaptive Mesh ◽  
Dynamic Load Balancing ◽  
Dynamic Features ◽  
Structured Adaptive Mesh Refinement ◽  
Two Phases

Dynamic load balancing(DLB) for parallel systems has been studied extensively; however, DLB for distributed systems is relatively new. To efficiently utilize computing resources provided by distributed systems, an underlying DLB scheme must address both heterogeneous and dynamic features of distributed systems. In this paper, we propose a DLB scheme for Structured Adaptive Mesh Refinement(SAMR) applications on distributed systems. While the proposed scheme can take into consideration (1) the heterogeneity of processors and (2) the heterogeneity and dynamic load of the networks, the focus of this paper is on the latter. The load-balancing processes are divided into two phases: global load balancing and local load balancing. We also provide a heuristic method to evaluate the computational gain and redistribution cost for global redistribution. Experiments show that by using our distributed DLB scheme, the execution time can be reduced by 9%- to using parallel DLB scheme which does not consider the heterogeneous and dynamic features of distributed systems.

scholarly journals Towards a 3-Dimensional Phase-Field Model of Non-Isothermal Alloy Solidification

2014 ◽  
Vol 783-786 ◽  
pp. 2166-2171 ◽  
Author(s):  
Andrew M. Mullis ◽  
Peter C. Bollada ◽  
Peter K. Jimack
Keyword(s):  
Phase Field ◽  
Adaptive Mesh Refinement ◽  
Phase Field Model ◽  
Lewis Number ◽  
Adaptive Mesh ◽  
Implicit Time ◽  
Dimensional Problem ◽  
Alloy Solidification ◽  
Field Problem ◽  
3 Dimensional

We review the application of advanced numerical techniques such as adaptive mesh refinement, implicit time-stepping, multigrid solvers and massively parallel implementations as a route to obtaining solutions to the 3-dimensional phase field problem for coupled heat and solute transport during non-isothermal alloy solidification. Using such techniques it is shown that such models are tractable for modest values of the Lewis number (ratio of thermal to solutal diffusivities). Solutions to the 3-dimensional problem are compared with existing solutions to the equivalent 2-dimensional problem.

Sign in / Sign up

Export Citation Format

Share Document