K&C’s Efficient Computation Fluid Dynamics (CFD) Solver for Multi-Phase and Chemically Reactive Flow Problems
ArunaCFD is an efficient CFD solver for simulating multi-phase and chemically reacting flow problems. K&C uses and validates ArunaCFD for problems ranging from explosive blast problems, subsonic/supersonic aerodynamics, to problems involving multi-phase gas dynamics and combustion.
ArunaCFD uses a Piecewise Parabolic Method (PPM) solver [1], a higher-order extension of Gudunov’s finite volume method, to solve the reactive Euler equations for fluid and gas dynamics. PPM is much more efficient and accurate than most second-order algorithms. PPM excels in problems involving discontinuities, such as those involving shocks and contact discontinuities. ArunaCFD also includes multiple equation of state (EOS) for both ideal and real gases, including Jones-Wilkens-Lee (JWL) variants of EOSs commonly used to model ideal explosive detonations.
Features & Benefits
- Solves the multi-species form of Euler’s equations in 3D. The solver can consequently model many important explosive blast, aerodynamics, and combustion problems.
- Fully compressible and multiphase capable, including treatments for fluid-particle coupling. Particles can be treated as either Euler-Lagrange tracer particles with two-way coupling or through Euler-Euler continuum treatments.
- Includes combustion physics and various EOSs for ideal/real gases, including reactive models, particle combustion models, and multi-species continuum combustion models.
- Block mesh code structure that is optimized for MPI parallelization. The solver is consequently very efficient and scalable on high-performance computing clusters.
- Accounts for complex geometries using an Embedded Boundary Method (EBM) implemented in ArunaCFD [2]. The user can insert any STL file directly from CAD to account for arbitrary embedded boundaries.
K&C’s current efforts for ArunaCFD development are in validating and extending the solver for new challenging fluid dynamics problems, including those involving fluid-structure interaction.
[1] Colella, P., Woodward, P.R., “The Piecewise Parabolic Method (PPM) for Gas-Dynamical Simulations,” J. Comp. Phys., 54, pp. 174-201, 1984.
[2] Ning, J., Tianbao, M., Lin, G., “A grid generator for 3-D explosion simulations using the staircase boundary approach in Cartesion coordinates based on STL models,” Adv. Eng. Soft., 67, pp. 148-155, 2014.
Stereolithography (STL) Files
ArunaCFD supports embedding boundaries using Stereolithography (STL) files. An STL file approximates the surfaces of a solid model with triangles by storing the 3 vertices and a normal direction. ArunaCFD employs the staircase methodology to slice the STL file into layers, and embed the surface into the CFD mesh.
Applications for ArunaCFD
- Flow in complex geometries
- Chemical reactions/Heat transfer
- Multiphase flows (gas-solid-particle flows)
- Unsteady flows (Shock Tube, particle-solid interactions, obscurant dissemination)
- Shock waves and other blast effects (ShockTube problem, Beirut simulation)
Beirut Simulation
A major challenge area in compressible CFD is computing accurate blast load simulations in geometrically large and complex scenes. Many CFD computations can be made to look realistic, but care in selecting a grid size that allows the solver to accurately track shock fronts while balancing computational resources available for the computation is a critical component of predicting accurate blast loads for scenarios like this. One example is the computation for the large accidental explosion that occurred at the Port of Beirut on August 4, 2020. Here, ArunaCFD is used by importing a 3D model (.STL file) for the entire City of Beirut and modeling the explosion using the ArunaCFD’s JWL model.
