About

Farzad Mashayek is a Professor of Aerospace and Mechanical Engineering and serves as the Department Head at the University of Arizona. He is a member of the Graduate Faculty and specializes in research areas including turbulent reacting flow, plasma flow, electrostatic atomization, solid ion batteries, computational methods, and machine learning applications. His academic background includes a PhD in Mechanical Engineering from the State University of New York at Buffalo, an MS in Mechanical Engineering from Sharif University of Technology in Tehran, Iran, and a BS in Mechanical Engineering from the same university. Mashayek's work experience spans multiple institutions, notably the University of Illinois at Chicago, where he held various positions from 2008 to 2022, and the University of Hawaii at Manoa. His research contributions include advancing understanding in fluid dynamics, electrohydrodynamics, and energy systems, with numerous publications in reputable journals. He has also been recognized with awards such as the Sustained Service Award from the American Institute of Aeronautics and Astronautics and the Best Presentation Award at the International Conference on Computational Mathematics, Parallel and Distributed Computing.

Research topics

• Composite material
• Chemical engineering
• Machine Learning
• Materials science
• Computer Science
• Engineering
• Physics
• Simulation
• Organic chemistry
• Physical chemistry
• Chemistry
• Nanotechnology

Selected publications

• Self-tuning dynamic explicit modal filtering based on local flow characteristics for large-eddy simulation

  Physics of Fluids · 2026-01-01

  articleSenior author

  This work improves upon our previously introduced explicit dynamic modal filter (DEMF) within the framework of the discontinuous Galerkin spectral element method (DGSEM) by introducing a mechanism for self-tuning of the model parameters. The new self-tuning dynamic explicit modal filter (STDEMF) also extends the methodology for obtaining modal values from nodal values beyond Chebyshev grids and polynomials to general collocation points and orthogonal polynomial bases by leveraging orthogonality. The generated modes are used to remove the built-up energy due to unresolved sub-grid scales (SGSs) in large-eddy simulation (LES) of turbulent flows. The STDEMF improves the performance of DEMF in two ways. First, the filter kernel applied to the modes is adapted from a cutoff kernel to a hyperbolic tangent shape, which automatically adjusts the model for different polynomial orders. Second, the cutoff mode is computed dynamically for each element as a function of local flow characteristics, including the local Kolmogorov length scale and the second invariants of the strain and rotation rate tensors. The suggested formulation for the cutoff mode treats unresolved elements distinctly and improves performance by avoiding under- or over-dissipation. Moreover, the cutoff mode evolves over time within the same element as turbulent characteristics vary. The model is evaluated on three flows: homogeneous isotropic decaying, the Taylor–Green vortex, and periodic channel flow, each with distinct turbulent characteristics. Comparisons of the results show that the STDEMF model outperforms the DEMF model and the Smagorinsky eddy viscosity model.

  PublisherDOI

• Evolution of grain boundaries in multi-principal alloys: Insights into phase stability and structural complexity

  Computational Materials Science · 2026-03-09

  article
  PublisherDOI

• Capillary breakup of liquid jets in the dripping regime and successive drop impacts on a solid surface

  International Journal of Numerical Methods for Heat &amp Fluid Flow · 2026-02-23

  articleSenior author

  Purpose The aim of this paper is to present a fully encompassing numerical simulation of a spatially developing capillary jet emanating from a nozzle, followed by sequential pinch-off, free fall and successive drop impacts onto a solid surface, and to quantify energy exchanges during these stages. Design/methodology/approach Axisymmetric laminar air-water flow is described with a fully coupled, fully implicit Cahn−Hilliard−Navier−Stokes phase-field formulation within the Multiphysics Object-Oriented Simulation Environment finite element framework. Adaptive mesh refinement and adaptive time-stepping, together with a degenerate mobility, resolve multiscale interfacial dynamics while preserving the mass of the main jet and satellite drops. For a fixed nozzle-to-substrate distance, the inlet velocity is varied to obtain periodic dripping and dripping-faucet regimes. The jet and drop flow stages are examined through energy transfer pathways among kinetic, surface, gravitational and dissipative modes. Findings In periodic dripping, breakup periods and detached-drop volumes agree closely with Tate’s law. Successive impacts reveal rapid interface swelling, a pinned-to-unpinned contact-line transition driven by capillary waves and renewed spreading. The periodic-regime energy budget indicates repeatable energy pathways across detachment, impact and spreading. In the dripping-faucet regime, pinch-off is chaotic with strongly varying drop volumes; overlap of rebound and impact phases generates stronger capillary waves and sequential bubble entrapments, and the energy budget reveals destructive momentum interference and enhanced dissipation after impacts. Originality/value This work delivers a mass-conservative phase-field simulation from jet formation to multiple impacts and a time-resolved energy budget across all stages, providing new physical insights into the mechanisms governing drop-train processes relevant to inkjet printing.

  PublisherDOI

• On the energy analysis of two-phase flows simulated with the diffuse interface method

  Physics of Fluids · 2025-07-01 · 3 citations

  articleSenior author

  The phase-field method (PFM) is employed to simulate two-phase flows with the fully coupled Cahn–Hilliard–Navier–Stokes equations governing the temporal evolution. The methodology minimizes the total energy functional, accounting for diffusive and viscous dissipations. A new perspective is presented by analyzing the interplay between kinetic energy, mixing energy, and viscous dissipation using the temporal evolution of the total energy functional. The classical surface energy is approximated with mixing energy under specific conditions, and the accuracy of this substitution is rigorously evaluated. The energy-based surface tension formulation derived from the Korteweg stress tensor demonstrates exceptional accuracy in capturing variations in the mixing energy. These concepts are demonstrated by considering two benchmark problems: droplet oscillation and capillary thread breakup. Key findings include validating mixing-energy theory for highly deformed interfaces, as well as the discovery of distinct energy dissipation patterns during thread breakup and droplet oscillations. The results highlight the robustness of the free energy-based PFM in accurately capturing complex interfacial dynamics, while maintaining energy conservation.

  PublisherDOI

• On the Energy Analysis of Two-phase Flows Simulated with the Diffuse Interface Method

  arXiv (Cornell University) · 2025-01-20

  preprintOpen accessSenior author

  The Phase-Field Method (PFM) is employed to simulate two-phase flows with the fully-coupled Cahn-Hilliard-Navier-Stokes (CHNS) equations governing the temporal evolution. The methodology minimizes the total energy functional, accounting for diffusive and viscous dissipations. A new perspective is presented by analyzing the interplay between kinetic energy, mixing energy, and viscous dissipation using the temporal evolution of the total energy functional. The classical surface energy is approximated with mixing energy under specific conditions, and the accuracy of this substitution is rigorously evaluated. The energy-based surface tension formulation derived from the Korteweg stress tensor demonstrates exceptional accuracy in capturing variations in the mixing energy. These concepts are demonstrated by considering two benchmark problems: droplet oscillation and capillary thread breakup. Key findings include validating mixing-energy theory for highly deformed interfaces, as well as the discovery of distinct energy dissipation patterns during thread breakup and droplet oscillations. The results highlight the robustness of the free energy-based PFM in accurately capturing complex interfacial dynamics, while maintaining energy conservation.

  PublisherOA PDFDOI

• Self-Tuning Dynamic Explicit Modal Filtering Based on Local Flow Characteristics for Large-Eddy Simulation

  ArXiv.org · 2025-12-02 · 1 citations

  preprintOpen accessSenior author

  This work improves upon our previously introduced explicit dynamic modal filter (DEMF) within the framework of the discontinuous Galerkin spectral element method (DGSEM) by introducing a mechanism for self-tuning of the model parameters. The new self-tuning dynamic explicit modal filter (STDEMF) also extends the methodology for obtaining modal values from nodal values beyond Chebyshev grids and polynomials to general collocation points and orthogonal polynomial bases by leveraging orthogonality. The generated modes are used to remove the built-up energy due to unresolved sub-grid scales (SGS) in large-eddy simulation (LES) of turbulent flows. The STDEMF improves the performance of DEMF in two ways. First, the filter kernel applied to the modes is adapted from a cut-off kernel to a hyperbolic tangent shape, which automatically adjusts the model for different polynomial orders. Second, the cut-off mode is computed dynamically for each element as a function of local flow characteristics, including the local Kolmogorov length scale and the second invariants of the strain and rotation rate tensors. The suggested formulation for the cut-off mode treats unresolved elements distinctly and improves performance by avoiding under- or over-dissipation. Moreover, the cut-off mode evolves over time within the same element as turbulent characteristics vary. The model is evaluated on three flows, homogeneous isotropic decaying, the Taylor-Green vortex, and periodic channel flow, each with distinct turbulent characteristics. Comparisons of the results show that the STDEMF model outperforms the DEMF model and the Smagorinsky eddy viscosity model.

  PublisherOA PDFDOI

• Electro-Stretching and Electro-Coalescence of Sessile Drops of Conducting Polymer Solutions with and without Surfactant and Dielectric Particles

  Langmuir · 2025-09-24

  article

  The present study explores electrically driven stretching of individual conducting polymer drops and electro-coalescence of drop pairs on a dielectric surface under a strong electric field of 10 kV. Conducting PEDOT:PSS and PEDOT:PSS–PEO [poly(3,4-ethylenedioxythiophene):polystyrenesulfonate–poly(ethylene oxide)] drops were tested with and without a nonionic surfactant (Silwet L-77) and dispersed titanium dioxide (TiO2) particles. The surfactant dramatically reduced the solution’s surface tension from ∼70 to ∼20 mN/m, and PEO doping increased viscosity and imparted shear-thinning behavior. Under the applied field, drops stretched between the electrodes and spread much wider than without voltage. This pronounced stretching is driven by electrostatic Maxwell stress overcoming capillarity (the electric capillary number CaE ∼ 0.9–2.3). The surfactant further enhanced deformation by lowering surface tension, and polarizable TiO2 particles introduced dielectrophoretic forces that also eased stretching. Furthermore, in surfactant-free cases, two initially separate drops underwent rapid electro-coalescence: upon field activation, finger-like protrusions formed within ∼2–5 ms from each drop to meet and create a narrow liquid bridge, which then expanded to merge the drops into one over a few seconds. However, drops containing surfactant (and TiO2) failed to coalesce, as strong Marangoni flow from surfactant-induced surface tension gradients dominated the Maxwell stress-driven attraction. Such surfactant-laden drops instead developed dendrite-like patterns at their trailing edges, with only a brief (∼millisecond) “handshake” contact and no full merging. These findings clarify how solution composition and interfacial and electrohydrodynamic mechanisms govern drop deformation and merging, providing insights for controlling drop behavior in coating processes. Moreover, the present experiments with drops of solutions of the conducting polymer with a surfactant (a superspreader SILWET L-77) and particles added reveal a novel phenomenon─a competition of the concentration-gradient Marangoni flow with electro-coalescence driven by the electric Maxwell stresses, which causes a noncoalescence even at a very high applied voltage.

  PublisherDOI

• MOOSE-based finite element framework for mass-conserving two-phase flow simulations on adaptive grids using the diffuse interface approach and a Lagrange multiplier

  Journal of Computational Physics · 2025-01-17 · 10 citations

  articleSenior authorCorresponding
  PublisherDOI

• Evolution of Grain Boundaries in Multi-Principal Alloys: Insights into Phase Stability and Structural Complexity

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Ab initio modeling and experimental analysis of electronic conductivity in PEDOT:PSS-PEO films for extrusion-based manufacturing

  Journal of Colloid and Interface Science · 2024-06-22 · 10 citations

  article
  PublisherDOI

Recent grants

• Fundamental Understanding of SEI Effects on Li Dendrite Formation and Growth

  NSF · $81k · 2022–2024

• GOALI: Controlled Coating via Charged Droplet Impact and Deposition on Dielectric and Conducting Surfaces

  NSF · $165k · 2022–2024

• GOALI: Controlled Coating via Charged Droplet Impact and Deposition on Dielectric and Conducting Surfaces

  NSF · $429k · 2019–2023

• Fundamental Understanding of SEI Effects on Li Dendrite Formation and Growth

  NSF · $353k · 2018–2023

• Collaborative: Plasma deposition of thin films on nanowires and particles

  NSF · $178k · 2007–2012

Frequent coauthors

• Vitaliy Yurkiv

  78 shared

• Reza Shahbazian‐Yassar

  University of Illinois Chicago

  59 shared

• Alexander L. Yarin

  54 shared

• Ajaykrishna Ramasubramanian

  26 shared

• Marco Ragone

  University of Illinois Chicago

  25 shared

• Jonathan Komperda

  University of Illinois Chicago

  23 shared

• Anmin Nie

  Yanshan University

  23 shared

• Tara Foroozan

  University of Illinois Chicago

  17 shared

Education

• PhD/Mechanical Engineering, Mechanical and Aerospace Engineering

  SUNY at Buffalo

  1994

• MS/Mechanical Engineering, Mechanical Engineering

  Sharif University of Technology

  1988

Awards & honors

• Sustained Service Award American Institute of Aeronautics an…
• Best Presentation Award The 20th International Conference on…