Publications

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Journal Publications

  1. J. Chang, S. Karra, and K. B. Nakshatrala, "Large-scale optimization-based non-negative computational framework for diffusion equations: Parallel implementation and performance studies", Journal of Scientific Computing, 70: 243-271, 2017 [arXiv link]
  2. J. Chang, K. B. Nakshatrala, and J. N. Reddy, "Modification to Darcy-Forchheimer model due to pressure-dependent viscosity: Consequences and numerical solutions", Journal of Porous Media, 20: 263-285, 2017
  3. J. Chang and K. B. Nakshatrala, "Variational inequality approach to enforcing the non-negative constraint for advection-diffusion equations", Computer Methods in Applied Mechanics and Engineering, 320: 287-334, 2017 [arXiv link]
  4. J. Chang, K. B. Nakshatrala, M. G. Knepley, and L. Johnsson, "A performance spectrum for parallel computational frameworks that solve PDEs", Concurrency and Computation: Practice and Experience, Submitted [arXiv link]
  5. N. Karthik, J. Chang, and K. B. Nakshatrala, "A scalable variational inequality approach for flow through porous media models with pressure-dependent viscosity", in preparation.
  6. J. Chang, K. B. Nakshatrala, S. Karra, and M. G. Knepley, "A comparative study between the variational inequality and the log transformation for reactive transport modeling", in preparation.

Invited Talks

  1. "Structure-preserving high performance computational methods for transport in porous media", J. Chang, CAAM Colloquium Series, Rice University, Sep 18, 2017
  2. "High performance computing in subsurface transport numerical simulations", J. Chang, CIVE Graduate Seminar Series, University of Houston, Sep 9, 2016
  3. "Least-squares finite element formulations for flow problems", J. N. Reddy, K. B. Nakshatrala, and J. Chang, American Geophysical Union (AGU) Fall Meeting, San Francisco, CA, Dec 3-7, 2012

Oral/Poster Presentations

  1. "A performance spectrum for parallel computational frameworks for solving PDEs", J. Chang, K. B. Nakshatrala, M. G. Knepley, and L. Johnsson, Firedrake '17 Workshop, London, UK, Mar 27-28, 2017 [Oral]
  2. "Operator-splitting and variational inequalities for the non-negative solution of advection-diffusion equations", J. Chang and K. B. Nakshatrala, American Geophysical Union (AGU) Fall Meeting, San Francisco, CA, Dec 12-16, 2016 [Poster]
  3. "A performance model to predict the strong-scaling potential of various finite element methods", J. Chang and K. B. Nakshatrala, Scientific Software Days (SSD), Austin, TX, Feb 25-26, 2016 [Poster]
  4. "A new approach to enforce element-wise mass/species balance using the augmented Lagrangian method", J. Chang and K. B. Nakshatrala, American Geophysical Union (AGU), San Francisco, CA, Dec 14-18, 2015 [Poster]
  5. "A comparative study on the parallel performance of locally conservative mixed finite element formulations for Darcy problems", J. Chang, K. B. Nakshatrala, and L. Johnsson, 13th US National Congress of Computational Mechanics (USNCCM13), San Diego, CA, Jul 26-30, 2015 [Oral and Poster]
  6. "Large-scale optimization-based non-negative computational framework for diffusion-type equations: Parallel Implementation and performance studies", J. Chang, S. Karra, and K. B. Nakshatrala, PETSc Conference and Tutorial, Chicago, IL, June 15-18, 2015 [Poster]
  7. "A comparative study on the computational efficiency of locally conservative finite element methods for subsurface flows", J. Chang, K. B. Nakshatrala, and L. Johnsson, 18th International Conference on Finite Elements in Flow Problems, Taipei, Taiwan, Mar 16-18, 2015 [Oral]
  8. "A methodology to ensure local mass conservation for porous media models under finite element formulations based on convex optimization", J. Chang and K. B. Nakshatrala, American Geophysical Union (AGU) Fall Meeting, San Francisco, CA, Dec 15-19, 2014 [Poster]
  9. "On the performance of maximum-principle enforcing methods applied to large-scale subsurface problems", S. Karra, J. Chang, and K. B. Nakshatrala, American Geophysical Union (AGU) Fall Meeting, San Francisco, CA, Dec 15-19, 2014 [Poster]
  10. "Computational performance of locally conservative methods for large-scale flow and transport through porous media", J. Chang, S. Karra, and K. B. Nakshatrala, 14th US National Congress on Theoretical and Applied Mechanics (USNCTAM), East Lansing, MI, Jun 15-20, 2014 [Oral]
  11. "On modifications to Darcy model and associated mixed formulations", J. Chang and K. B. Nakshatrala, 12th US National Congress on Computational Mechanics, Raleigh, NC, Jul 22-25, 2013 [Oral and Poster]