Christopher Ivey's Email Addresses & Phone Numbers

Research Scientist @ Cascade Technologies Inc. Palo Alto, CASummer Intern @ AES Consulting Engineers I imported the paper edits applied by the PE into the AutoCAD drawings for the associated civil engineering projects. From June 2007 to September 2007 (4 months) Gloucester, VAPostdoctoral Fellow @ Lawrence Livermore National Laboratory I was a part of the NextGen project,...

Research Scientist @ Cascade Technologies Inc. Palo Alto, CASummer Intern @ AES Consulting Engineers I imported the paper edits applied by the PE into the AutoCAD drawings for the associated civil engineering projects. From June 2007 to September 2007 (4 months) Gloucester, VAPostdoctoral Fellow @ Lawrence Livermore National Laboratory I was a part of the NextGen project, adding adaptive meshrefinement (AMR) capabilities to Miranda, a radiation hydrodynamics code designed for large-eddy simulation (LES) of multicomponent flows with turbulent mixing. From July 2016 to January 2017 (7 months) Livermore, CAGraduate Research Assistant/ Stanford Graduate Fellow in the Center for Turbulence Research @ Stanford University I developed a geometric volume-of-fluid framework, consisting of many novel algorithms, for simulating two-phase flows on unstructured meshes using CharLES. The collocated node-based finite-volume two-phase flow solver uses the median-dual mesh, so I created set of data structures and algorithms for non-convex polyhedral operations. The polyhedral library is leveraged to develop an accurate and conservative advection operator used in the transport mass and momentum near the interface, as well as to create an accurate and convergent method for extracting interface normals and curvatures. The computational tools are further utilized to formulate a stable and empirically second-order accurate fractional step method for the immiscible system. The high-order finite-volume operators from CharLES are used in the pressure projection, diffusion, and advection terms away from the interface. The solver is written in C++. MPI and ParMetis are used to partition the domain. Jacobi+AMG preconditioning with restarted GMRES, performed with DOE ML and AztecOO packages of the Trilinos suite, are used to stably solve the stiff variable-density Poisson equation. The two-phase solver is used to investigate the primary atomization of JP-8 fuel from a Bosch common rail fuel injector at Spray A conditions, the formation of micro-bubbles during the high-speed impact between a drop and a liquid surface, and the breakup of a round water jet by a high speed annular air jet. The detailed simulations are used to educate the development of subgrid models to be used in LES. From September 2010 to June 2016 (5 years 10 months) Stanford, CAComputational Science Graduate Fellow @ U.S. Department of Energy The burning of oil, although unfavorable from a conservational and environmental standpoint, is paramount to our economy for the widespread use of liquid combustion engines in our transportation system. Sadly, the physics of these systems still are poorly understood due to the enriched nature of multiphase flows, i.e. the mutual interaction of many subsystems causing simultaneous phenomena spanning a wide range of spatial and temporal scales. Of particular importance to the control and efficacy of liquid combustion engines is jet atomization, the breakup and evaporation of the liquid jet into a combustible fuel vapor-air mixture. I am developing multiphase flow models that can detail the jet atomization process in a full-scale liquid combustion simulation. The ever-changing topology and cascade of length scales involved in jet atomization preclude the use of explicit surface representations and point-particle methods, so I am developing algorithms based on implicit interface tracking schemes to respect the complexity of the system. I leverage the volume-of-fluid method extended by a piecewise linear interface calculation representation (VoF-PLIC) to represent the distinct phases, where the interface is represented by piecewise linear elements built from the volume fraction information. VoF-PLIC naturally accommodates breakup and coalescence of surfaces and it has the added value that it potentially preserves volume during advection. I develop schemes to conservatively advect the volume fraction and accurately reconstruct the surface on general grids using the VoF-PLIC information. Further, I research techniques to accurately estimate surface tension, to model evaporation, to model ligament and droplet breakup, and to couple VoF-PLIC with point-particle methods. From September 2010 to September 2014 (4 years 1 month) Undergraduate Research Assistant in the Applied Fluid Imaging Laboratory @ Johns Hopkins University I studied turbulent mixing with Rayleigh scattering. I gathered Rayleigh scattering data by imaging cross-sections of an axisymmetric jet that is interrogated by a pulsed laser-sheet. I wrote a Fortran 77 code to extract the turbulent scalar mixing of the jet species. I wrote Bash scripts to automate the process. From January 2009 to June 2010 (1 year 6 months) Baltimore, MDUndergraduate Research Assistant in the Laboratory for the Experimental Fluid Dynamics @ Johns Hopkins University I studied biological particulate dispersion in the ocean with submersible holography. I wrote Matlab and LabVIEW scripts to calculate concentrations, size, and spacing distributions of the biological particulates from the holographic graphic data. From September 2007 to June 2008 (10 months) Baltimore, MDDOE Computational Science Graduate Fellowship Practicum Intern @ Argonne National Laboratory I worked on optimizing an open-source Lattice Boltzmann code for the BG/Q architecture using MPI, OpenMP, and vectorization. I familiarized myself with parallel debuggers, profilers, and performance tools (TAU, Rice HPCToolkit and IBM HPCT) as well as the parallel visualization tools (Visit and ParaView). From July 2012 to November 2012 (5 months) Argonne, ILNASA Aeronautics Scholarship Program Fellow @ NASA Langley Research Center I performed CFD calculations of the Orion CEV RCS Jets at reentry using LAURA to compare with a previously performed NO PLIF experiment. I wrote Tecplot scripts and Fortran 90 code that mapped the the CFD fluid variables into a series of fluorescence images to provide a qualitative comparison with the NO PLIF images. I wrote scripts in Autodesk 3ds Max to interface the CAD model with a series of adjacent fluorescence images to create a composite three-dimensional model. The CFD fluorescence images were processed similarly to provide a qualitative three-dimensional comparison between experiment and simulation. From September 2009 to September 2010 (1 year 1 month) Hampton, VALangley Aerospace Research Student Scholar @ NASA Langley Research Center I worked in a group that studied hypersonic transition using nitric-oxide (NO) planar laser-induced fluorescence (PLIF). The experiments were conducted on a series of angled flat plates with discrete roughnesses, the Orbiter, and the Orion Crew Exploration Vehicle's (CEV) Reaction Control System (RCS) Jets. The experiments captured fluorescence data by imaging slices of the excited NO within the boundary layer or jet fluid. I wrote a LabVIEW program which would control the movement of lenses during the experiment so that the laser sheet would sweep through the tagged fluid, providing three-dimensional information of the interrogated region. I facilitated NO PLIF data analysis by writing Java programs that removed non-fluidic intensity contributions from the experimental images. From June 2008 to September 2009 (1 year 4 months) Hampton, VAUndergraduate Research Assistant in the Instrument Development Group @ Johns Hopkins University I studied cryogenic strains of lens materials to determine their suitability for satellite telescopes. I developed a DAQ system for measuring lens strains in a cryogenic chamber. I acquired and processed strain-temperature relations using Simulink and LabVIEW. From September 2008 to January 2009 (5 months) Baltimore, MD