September 2016 - Allocations-admins - mailman3.cels.anl.gov

[LCRC Accounts] Project Request: DFT_ALD_SiC
by accounts＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: Zhigang Mei Applicant's institution: ANL Applicant's division: NE Project Name: DFT_ALD_SiC Project title: Computational Design of Novel Precursors for Atomic Layer Deposition of SiC Associated funding: LDRD Innovate Other Systems: Carbon Science: The goal of the proposed work is to use a multi-scale computational approach (DFT+KMC) to down-select novel chemical precursors for atomic layer deposition (ALD) of SiC and identify the ideal process of ALD, and to verify the proposed precursors and reaction routines using experiments. In addition to gaining a better fundamental understanding of the underlying kinetics of the precursor-surface reaction, this research will help to identify new precursors and optimize deposition conditions for ALD of SiC at low temperatures. Low temperature ALD is preferred, as it will limit interdiffustion of the substrate and coating, reduce thermal stresses within the coating, and will maintain the initial desirable microstructure of zircaloy. The implications of the proposed activities can be extended beyond nuclear materials to other areas of interest, such as semiconductors. Project description: Our strategy to discover and develop new low-temperature, conformal process for SiC growth will be composed of the following steps: 1. Screening of Potential New Precursors Using Computational Methods To utilize computational methods to screen for potential new precursors, we will examine the available commercial crystal structure databases (e.g. Cambridge Structural Database) for Si- and C-containing materials and perform DFT calculations to determine the enthalpy of formation of SiC with these precursors. A thermodynamic database of chemical reactions between existing and hypothetical Si-containing and C-containing precursors (both organic and inorganic compounds) will be developed and pairs of precursors with the potentially lowest reaction temperatures will be selected for further study. The second step of the screening process is to carry out a fast evaluation of the precursor-surface interaction. We will use a simple slab model to study the precursor-surface interaction. The reaction energetics of the silicon and carbon precursors will be calculated by DFT and the activation energies of reactions will be predicted using Nudged Elastic Band method. At this level of detail, we will focus solely on the interaction of a single precursor molecule with growing surfaces. Under these conditions, we have demonstrated that the precursor surface interaction can be casted as a Markov chain process with the transition probabilities between states determined by the DFT calculations. This allows us to extract the exact probabilistic outcome of the precursor-surface interaction process by carrying out a single matrix inversion. We will incorporate the predicted thermodynamic properties of potential precursors into thermodynamic and kinetic models to evaluate their feasibil ity for the synthesis of SiC. These models, which were originally developed to study the epitaxial growth of SiC by CVD are based on the open source software Cantera, and can be interfaced with existing thermodynamic databases. This investigation can reveal the mechanism of film growth by ALD, identify the critical reactions during the ALD process, and estimate the temperature of deposition. 2. Detailed Simulation of the Precursor-Surface Interaction. It is well known that the complete ALD growth mechanism is extremely complicated, as it consists of surface reactions, structural relaxation and self-limiting surface chemistry. In this integrated approach (DFT+KMC), the ability to retain the accuracy of the atomistic model into the higher-scale model can lead to remarkable breakthroughs in our understanding of ALD process. To describe the ALD reactions of SiC from a combination of silicon-containing and carbon-containing precursors, a 3D on-lattice KMC model will be developed, similar to the model developed for HfO2 [Chem. Mater. 25, 878 (2013)]. All atomistic reaction pathways in DFT will be implemented as reaction events on the lattice. This contains all steps, from the early stage of adsorption of each ALD precursor, kinetics of the surface protons, interaction between the remaining precursors, influence of remaining fragments on adsorption sites, densification of each ALD precursor, migration of each precursor, and coope ration between the remaining precursors. The essential chemistry of the ALD reactions depends on the local environment at the surface. The coordination number and a neighbor list will be used to incorporate these dependencies. The validity and necessity of the proposed reaction pathways will be statistically established at the mesoscale. The formation of one monolayer of precursor fragments will be shown at the end of the pulse. The migration of the low coordinated remaining precursor fragments will be also proposed. This process introduces a slow re-ordering motion at the mesoscale, leading to the smooth and conformal thin film that is characteristic of ALD. The ALD application will be developed as a new feature in the stochastic parallel particle kinetic simulator (SPPARKS) code. In the first year, we will focus on screening of potential new precursors using high-throughput DFT computations. Our initial tests show that the computational time for a typical precursor pair such as SiI4 and CI4, takes about 800 cpu-hours. Due to the huge number of precursors for Si and C, we expect that about 500 pair of precursors will be studied. The total computational time is estimated to be about 400,000 cpu-hours. Industry partnership: Project URL: Requested allocation: 100000 Q1: 0 Q2: 0 Q3: 0 Q4: 100000 Justification: Storage requirements: 1 TB The requester has used undetermined amount hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System

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[LCRC Accounts] Yearly Allocation Request for CMFD-RANS
by accounts＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Dillon Shaver Project Name: CMFD-RANS Division: NE Project title: Development of Multiphase RANS turbulence models Associated funding: NEAMS LDRD NEUP Other Systems: Mira - shared project has ~25M CPU hours Science: The objective of this project is to develop and implement Unsteady Reynolds Averaged Navier-Stokes (uRANS) turbulence models in the Nek5000/Nek2P CFD code for use in multi-phase flow simulations. Project description: RANS and uRANS turbulence models are necessary for the accurate CFD simulation of flows on large scales, such as nuclear reactor fuel rod bundles and full cores. The current state-of-the art for simulation of boiling flows utilizes the RANS framework. Recently, the k-omega turbulence model has been demonstrated with Nek using a homogeneous equilibrium model of multiphase flow (thanks significantly to LCRC support). The goals of this project will be to further extend that model to more sophisticated formulations of multiphase flow, specifically the two-fluid model available in Nek-2P. This will enable the further development and validation of multi-phase models with Nek and the subsequent simulation of large, complex problems of interest in both science and industry. Additionally support for the development of the k-omega model will include simulations of a twin-jet mixing facility to evluate the model performce in capturing the effects of buoyancy a nd free-shear layers on turbulence. Both of which can play a signficant role in multiphase flows. This project will use the CFD code Nek5000 and its branch, Nek2P. Written in a combination of Fortran and C, Nek has been demonstrated to be a highly scalable code using the MPI library. Nek5000 has a long history of use and development on the LCRC systems. Proposed simulations will include helical pipe heat exchangers, nuclear reactor subchannels, and the turbulent mixing of twin jets. Meshes for these problems range in size from <100K elements to >1M elements. The project is expected to have between 2-4 members. Industry partnership: Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 400000 Q1: 100000 Q2: 100000 Q3: 100000 Q4: 100000 Justification: Storage requirements: 1TB Thank You, The LCRC Accounts System

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New LCRC report submitted for qmc_for_nuclei
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=qmc_for_nuclei

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New LCRC report submitted for CEES-II-Wolverton
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=CEES-II-Wolve…

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New LCRC report submitted for CEES-II-Wolverton
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=CEES-II-Wolve…

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[LCRC Accounts] Yearly Allocation Request for LES-Engine
by accounts＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Sibendu Som Project Name: LES-Engine Division: ES Project title: Computation Fluid Dynamics Modeling of Diesel Injectors and Fuel Sprays under Transient Operating Conditions Associated funding: DOE Office of Vehicle technologies Other Systems: University of Perugia Science: This project will use a Computation Fluid Dynamics (CFD) software called CONVERGE to model transient two phase flows in fuel injectors and combustion chambers using highly resolved Large Eddy Simulations (LES) in an Eulerian approach. The idea is to investigate high pressure fuel injectors, where needle opening and closing transients cause complex off-design fluid dynamics behaviors that profoundly impact the mixture formation processes and affect emission and combustion performance of engines. A new gas dissolution model is under development which will be integrated in the CFD code and will extend the prediction capability of the model. The simulation results and methodology developed in this projects will pave the way for novel and more efficient fuel injector design methods, for either gasoline or diesel engines. Project description: The project will be divided in the following parts. Initially, injection transients for single hole injectors will be simulated, without dissolution model. We will be studying the grid requirements, initialization of internal domain with liquid or liquid-gas mixture, effects of injection pressure and back-pressure. These simulations will run on about 64-256 cores, for few days. In a parallel stage, we will be testing the dissolution gas model on fuel injectors and other flow test devices. These simulations will require 64-128 cores for few days. Results will be compared against available experimental data collected at the APS. Once the correct setup of the time scale involved in the mass transfer process of cavitation and gas absorption/dissolution have been assessed, this information will be retained for the subsequent steps. Next, opening and closing injection transients will be simulated introducing the advancements derived from the dissolved gas mode l. Single and multi-hole injectors will be simulated in this last main part of the project at full resolution, and with the optimal multiphase flow code setup. These selected simulations will run on about 128-256 cores, for about two weeks each. Industry partnership: Convergent Science Project URL: http://www.transportation.anl.gov/engines/multi_dim_model_home.html Current FY Hours Used: undetermined amount New FY Requested allocation: 600000 Q1: 150000 Q2: 150000 Q3: 150000 Q4: 150000 Justification: Our recent publication (J. Kodavasal, K. Harms, P. Srivastava, S. Som, S. Quan, K.J. Richards, M. Garcia, “Development of stiffness-based chemistry load balancing scheme, and optimization of I/O and communication, to enable massively parallel high-fidelity internal combustion engine simulations,” Journal of Energy Resource Technology; JERT-16-1022, 2016) together with MCS and Convergent Science discusses the improvements to the Converge tool that has resulted in significant improvement in scaling. Currently, we are able to scale the code up to 4096 processors on Mira with about 70% scaling efficiency for a fixed mesh size. This was achieved due to the implementation of: (1) MPI I/O, (2) Improved Communication, (3) METIS load balancing scheme, (4) Development of a new chemistry load balancing scheme. Storage requirements: 5 TB Thank You, The LCRC Accounts System

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New LCRC report submitted for QM_Storage
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=QM_Storage

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New LCRC report submitted for Cat_Biomass
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=Cat_Biomass

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New LCRC report submitted for chargetransport
by support＠lcrc.anl.gov 02 Sep '16

02 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=chargetranspo…

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New LCRC report submitted for FF-opt
by support＠lcrc.anl.gov 01 Sep '16

01 Sep '16

Full project report at https://accounts.lcrc.anl.gov/reporting/project/2016/?project=FF-opt

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