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Koo, Heeseok

Publications and source records attributed to Koo, Heeseok.

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

DNS/LES Study of Representative Wall-Bounded Turbulent Flows using SIERRA/Fuego

This report summarizes a series of SIERRA/Fuego validation efforts of turbulent flow models on canonical wall-bounded configurations. In particular, direct numerical simulations (DNS) and large eddy simulations (LES) turbulence models are tested on a periodic channel, a periodic pipe, and an open jet for which results are compared to the velocity profiles obtained theoretically or experimentally. Velocity inlet conditions for channel and pipe flows are developed for application to practical simulations. To show this capability, LES is performed over complex terrain in the form of two natural hills and the results are compared with other flow solvers. The practical purpose of the report is to document the creation of inflow boundary conditions of fully developed turbulent flows for other LES calculations where the role of inflow turbulence is critical.

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DOE OSTI2017

A minimally-dissipative low-Mach number solver for complex reacting flows in Open$\mathrm{FOAM}$

Large eddy simulation (LES) has become the de-facto computational tool for modeling complex reacting flows, especially in gas turbine applications. However, readily usable general-purpose LES codes for complex geometries are typically academic or proprietary/commercial in nature. In this report the objective is to develop and disseminate an open source LES tool for low-Mach number turbulent combustion using the OpenFOAM framework. In particular, a collocated-mesh approach suited for unstructured grid formulation is provided. Unlike other fluid dynamics models, LES accuracy is intricately linked to so-called primary and secondary conservation properties of the numerical discretization schemes. This implies that although the solver only evolves equations for mass, momentum, and energy, the implied discrete equation for kinetic energy (square of velocity) should be minimally-dissipative. Here, a specific spatial and temporal discretization is imposed such that this kinetic energy dissipation is minimized. The method is demonstrated using manufactured solutions approach on regular and skewed meshes for a canonical flow and a lab-scale turbulent flow problem.

42 ENGINEERING↗
DOE OSTI2017

Rubble Fire Multi-Phase Model Development

This report presents multi-phase modeling approaches that are developed for simulating rubble fire scenarios similar to a large-scale rubble pool fire test at Sandia National Laboratories using composite materials and jet fuel. The rubble pool fire test burnt oddly shaped combustible solid objects submerged in liquid fuel. As an intermediate step toward a full scale rubble fire simulation, various model improvement tasks were performed. For modeling solid decomposition, a multi-step degradation model was used for canonical verification problems and the Chemical Percolation for Devolatilization (CPD) approach was implemented. Capabilities of Lagrangian particle approach has been extended such that a group of particles may represent a solid bulk. For gas-liquid interface, the volume of fluid (VOF) technique was implemented and relevant physics were added. The developed tools offer a potential for simulating three-phase (gas, liquid, and solid) combustion applications.

42 ENGINEERING↗