Babak Goshayeshi, Ph.D. ← Back to selected work

Doctoral research · Institute for Clean & Secure Energy · University of Utah

Two-Phase One-Dimensional Turbulence Model

Simulating the combustion of a single coal particle in laminar flow with fully detailed chemistry — resolving gas-phase kinetics, devolatilization, and char oxidation at a computational cost far below full 3-D direct numerical simulation.

●Computational modeling ●Numerical methods ●HPC ●Reacting multiphase flow

The result

The “CO Excalibur”

Carbon monoxide concentration in the gas phase around a single burning coal particle, resolved in space (horizontal) and time (vertical, top to bottom). The structure of the CO field traces the physics — each part of the “sword” corresponds to a distinct combustion mechanism.

CO concentration field around a burning coal particle, shaped like a sword: a narrow bright grip at top, a wide glowing guard at the ignition point, and a long diffuse blade below.
CO concentration produced by simulating single coal-particle combustion in laminar flow using detailed chemistry.

Grip char oxidation

The narrow early-time streak corresponds to production of CO by heterogeneous char oxidation at the particle surface.

Guard homogeneous ignition

The bright cross-piece marks the homogeneous ignition of CO in the gas phase — the moment the accumulated CO ignites.

Blade devolatilization

The long tail corresponds to production of CO by devolatilization of the coal particle as it heats and releases volatiles.

In the gas phase, detailed chemical kinetics based on the GRI 3.0 mechanism is utilized. On the particle side, models for vaporization, devolatilization, and char oxidation/gasification are considered; devolatilization uses the Chemical Percolation Devolatilization (CPD) model.

The model

Two coupled phases

The ODT model resolves the full range of length and time scales along a single line of sight, coupling a fully resolved gas phase to Lagrangian coal particles.

Gas phase

Conservation of mass, momentum, energy, and species are solved on the ODT line, with source terms coupling the gas to the particle phase.

Gas-phase conservation equations for mass, momentum, energy, and species, each with particle-coupling source terms.
Gas-phase governing equations with particle source terms.
Evolving velocity profile across the domain (m/s vs. width in mm).

Coal particle

Each particle carries submodels for evaporation, devolatilization (CPD), and char oxidation/gasification, exchanging mass, momentum, and heat with the gas.

Schematic of a coal particle showing evaporation, devolatilization, and char oxidation processes.
Coal-particle submodels: evaporation, devolatilization, char oxidation.
Evolving temperature profile across the domain.

Why it matters

From equations to scientific software

This work is the technical foundation behind my platform career: modeling complex physical systems, reducing computational cost with dimensional reduction, and translating advanced numerical methods into usable, high-performance scientific software. The same discipline now drives how I build computational platforms at DiPhyx.