Local Baroclinic Turbulence Models for Mixing
Abstract
This progress report presents tests and simulations of algorithms approximating the effects of fuel-oxidizer reactions on the turbulent flow computed by the 3D Coherent Structure Dynamics - Surrogate Fluid Dynamics (CSD-SFD) model. Expansion from gas-phase combustion cause density gradients and these generate additional turbulence as transient baroclinic pressures act on these density gradients. This baroclinic turbulence increases the rate of mixing and can accelerate the combustion. Direct Numerical Simulations (DNS) can resolve some details of these effects but the effective Reynolds numbers are very low and the computational costs are very high for practical situations. Here we use Coherent Structure Dynamics to provide a nonequilibrium turbulent spectrum over seven orders of magnitude in scale and use Surrogate Fluid Dynamics to simulate 3D mixing from this spectrum. CSD-SFD runs on a laptop in an hour or two for 1024-cubed grids. The price for this 100 to 1000-fold speed increase over CFD is the use of a fundamentally incompressible convection model. The compressibility effects of baroclinic turbulence must be grafted onto the SFD model. This progress report presents tests and results of two computationally efficient approaches to approximate the added mixing that results from baroclinic turbulence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 29, 2022
- Accession Number
- AD1173081
Entities
People
- Jay Boris
- Keith Obenschain
Organizations
- United States Naval Research Laboratory