(6jl) Multiscale Computation of Miscroscale Fluid Dynamics in Porous Materials

Research Interests:
A grand challenge of our generation is the procurement of clean sustainable energy and water, while minimizing environmental footprints. In meeting this challenge, porous materials occupy a very central role. As geologic rocks, they are the very medium for geothermal energy, CO₂ sequestration, unconventional hydrocarbon, and groundwater remediation. They also serve as key components in Li-batteries and fuel cells. The scientific focus of my research is to understand and develop capabilities to predict and control multiphase fluid dynamics in porous media at the micron scale and to translate this knowledge to large-scale engineering systems. My approach involves: (i) characterizing porous materials via multiscale imaging techniques that combine microscopy, spectroscopy, and optics, (ii) simulating fluid dynamics at the microscale to optimize design and operational controls, and (iii) scaling microscopic predictions to large engineering systems via multiscale multiphysics computation. I focus my attention on short- as well as long-term solutions to key problems facing our energy and water security, such as: CO₂ sequestration, geothermal energy, oil/gas recovery (shale), ground water, and fuel cells.

Postdoctoral Projects:

• “Multiscale computation of multiphase fluid dynamics in porous materials for rapid fluid-structure optimization”
• “High-resolution imaging of hydro-thermo-mechanical properties of geologic porous materials (e.g., shales)”

Advisor: Prof. Hamdi Tchelepi, Energy Resources Engineering Department, Stanford University, CA

PhD Dissertation:

• Title: “Modeling single-phase flow and solute transport across scales”

  Focus:
  1) Implications of CO2-mineral-water interactions on leakage in geologic carbon storage
  2) Multiscale methods for bridging microscopic physics to macroscopic observations

  Advisor: Prof. Matthew Balhoff, Petroleum & Geosystems Engineering Department, University of Texas at Austin, TX

Research Experience:
My career is a mixture of chemical and petroleum engineering, computational physics, applied mathematics, and hydrology. However, the question I have always deeply cared about is our energy, water, and environmental security and the role porous materials play to provide it. My undergraduate training was in chemical and petroleum engineering. But my graduate research drove me heavily into applied mathematics, computational physics, and high performance computing. I developed new mathematical methods for modeling reactive flow and transport in porous media at a variety of scales (micron to meter). Simultaneously, I collaborated closely with microfluidic experimentalists to validate/enrich my models. In my postdoc, I developed multiscale techniques to accelerate multiphase flow simulations, which enabled fluid-structure optimizations in a variety of applications (electrodes, membranes, oil recovery). I also developed experimental imaging techniques for mapping hydro-thermo-mechanical properties of geomaterials (e.g., oil/gas shales). This involved training in hyperspectral imaging, microscopy (SEM, FIB, fluorescence), FTIR/Raman spectroscopy, and optical spectrophotometry to name a few. My modeling background gave a unique way of approaching experimentation, in which I could identify data most useful to modelers. The combination of experiments and modeling also enabled me to identify important opportunities for research and allowed me to communicate and collaborate with several colleagues across various universities and national laboratories (PNNL, LBNL, Sandia).

Teaching Experience:

Philosophy. Students graduating from universities today face the biggest global challenges in the water, energy, and environmental sectors since the beginning of human history. My contention is that quantitative literacy in basic sciences as well as creativity is what equips them to solve these problems in the future, which should be given equal weight in their education.

University of Texas at Austin. I was a teaching assistant for the undergraduate Numerical Methods and Programming course (60 students). I designed and graded homework, held in-class programming sessions, and gave review lectures. I always looked forward to the office hours where I could interact and help some of the more reserved and struggling students, who refrained from asking questions in class. I received an evaluation score of 4.2/5, among highest for the course. I was also an undergraduate research mentor of three summer interns to develop a computer model for non-Newtonian flow in porous media. I taught programming, non-Newtonian fluid mechanics, and encouraged collaboration and discussions to promote creativity and teamwork. In the end, the project finished one month ahead of schedule and one of the students joined our group.

Stanford University. I co-instructed the graduate Multiphase Flow in Porous Media course (22 students) taught by my postdoctoral advisor. I prepared lecture notes, taught in-class, and designed homework. Even though no formal evaluation was conducted, both times I received very positive feedback from several students and my advisor.

Teaching Interests/Future Direction:
As a faculty I will apply my expertise in porous media science to develop transformational solutions to provide sustainable energy and water for future generations. Among other directions, I am interested in the following areas:

Fuel cells and battery optimization. Fuel cells and batteries are very promising technologies for harnessing renewable energy. They can also be used for in-situ conversion of fossil fuels to cleaner hydrogen. They consist of several porous components. Device-level optimizations ensure membrane-electrode-assemblies that have maximal power output (minimal transport/ohmic losses). Experimental and modeling techniques (μ-tomography, domain decomposition) that incorporate microstructural effects allows optimizing design and operational controls.

CO₂ storage & enhanced oil recovery. While we transition from fossil energy to renewables, it is important to continue providing energy for a growing global population while simultaneously managing carbon. Geologic carbon storage coupled to enhanced oil recovery is an attractive option. The problems: (a) safety issues regarding CO₂ leakage, and (b) poor displacement of heavy hydrocarbons. Fluids with optimal rheological/interfacial properties can be identified through microscopic fluid dynamics simulations followed by their synthesis in the lab. This leads to custom-designed fluids for a given rock/reservoir type, cutting-down on conventional trial-and-error experimentation. The outcome is of interest to oil companies and regulatory agencies.

Sustainable shale gas development. Two biggest concerns in shale gas development are: (a) how to minimize water usage, and (b) how to increase production without inducing seismicity. While natural gas remains the cleanest form of fossil energy, these public concerns must be addressed to avoid irreversible environmental damage. The high heterogeneity of these geomaterials further complicates analysis. Micro/nanofluidic experiments and modeling coupled to image-based characterization (microscopy/spectroscopy) of shales hold immense potential for increased sustainability.

I am also very interested in designing fouling-resistant membranes, implications of biomass growth at river-aquifer interfaces on contaminant transport and climate change, increasing the efficiency of geothermal energy production and storage, drug delivery in vascular networks (some of my PhD work focused on flow and transport in general graph-based networks).

Selected Publications:
1. Mehmani, Y., Tchelepi, H.A., “Multiscale computation of pore-scale fluid dynamics: two-phase flow.” Journal of Computational Physics, (in prep).
2. Mehmani, Y., Tchelepi, H.A., “Multiscale computation of pore-scale fluid dynamics: single-phase flow.” Journal of Computational Physics, (in review).
3. Mehmani, Y., Tchelepi, H.A., “Minimum requirements for predictive pore-network modeling of solute transport in micromodels.” Advances in Water Resources, (2017).
4. Mehmani, Y., Burnham, A.K., Vanden Berg, M.D., Tchelepi, H.A., “Quantification of organic content in shales via near-infrared imaging: Green River Formation.” Fuel, (2017).
5. Mehmani, Y., Burnham, A.K., Tchelepi, H.A., “From optics to upscaled thermal conductivity: Green River oil shale.” Fuel, (2016).
6. Mehmani, Y., Burnham, A.K., Vanden Berg, M.D., Gelin, F., Tchelepi, H., “Quantification of kerogen content in organic-rich shales from optical photographs.” Fuel, (2016).
7. Mehmani, Y., Balhoff, M.T., “Eulerian network modeling of longitudinal dispersion.” Water Resources Research, (2015).
8. Mehmani, Y., Balhoff, M.T., "Mesoscale and hybrid models of fluid flow and solute transport." Reviews in Mineralogy and Geochemistry, (2015).
9. Mehmani, A., Mehmani, Y., Prodanović, M., Balhoff, M.T. "A forward analysis on the applicability of tracer breakthrough profiles in revealing the pore structure of tight gas sandstone and carbonate rocks." Water Resources Research, (2015).
10. Yang, X., Mehmani, Y., Perkins, W.A., Pasquali, A., et al. “Intercomparison of 3D pore-scale flow and solute transport simulation methods”, Advances in Water Resources, (2015).
11. Mehmani, Y., Balhoff, M.T., “Generalized semi-analytical solution of advection-diffusion-reaction in finite and semi-infinite cylindrical ducts.” Int. Journal of Heat and Mass Transfer, (2014).
12. Mehmani, Y., Oostrom, M., Balhoff, M.T., “A streamline splitting pore-network approach for computationally inexpensive and accurate simulation of species transport in porous media,” Water Resources Research, (2014).
13. Oostrom, M., Mehmani, Y., Romero-Gomez, P., Tang, Y., Liu, H., Yoon, H., Kang, Q., et al. "Pore-scale and continuum simulations of solute transport micromodel benchmark experiments." Computational Geosciences, (2014).
14. Altman, S.J., Aminzadeh-Goharrizi, B., … Mehmani, Y., … (alphabetical order) "Chemical and hydrodynamic mechanisms for long-term geological carbon storage." The Journal of Physical Chemistry C, (2014).
15. Mehmani, Y., Balhoff, M.T., “Bridging from pore to continuum: a hybrid mortar domain decomposition framework for subsurface flow and transport.” SIAM Journal of Multiscale Modeling and Simulation, (2014).
16. Mehmani, Y., Sun, T., Balhoff, M.T., Eichhubl, P., Bryant, S., "Multiblock pore-scale modeling and upscaling of reactive transport: application to carbon sequestration." Transport in Porous Media, (2012).
17. Sun, T., Mehmani, Y., Balhoff, M.T. “Hybrid multiscale modeling through direct substitution of pore-scale models into near-well reservoir simulators.” Energy & Fuels, (2012).
18. Sun, T., Mehmani, Y., Bhagmane, J., Balhoff, M.T., "Pore to continuum upscaling of permeability in heterogeneous porous media using mortars." Int. Journal of Oil, Gas and Coal Technology, (2012).
19. Balhoff, M., Sanchez-Rivera, D., Kwok, A., Mehmani, Y., Prodanović, M., "Numerical algorithms for network modeling of yield stress and other non-Newtonian fluids in porous media." Transport in porous media, (2012).