Constructing Inflow Profiles for Large-eddy Simulations Using Dynamic Mode Decomposition

Emmet Cleary, California Institute of Technology

In practical large-eddy simulations (LES) of turbulent flows, it is common to use inflow profiles of fully developed turbulence as boundary conditions. This is done by making a database from prior canonical LES. However, the database is finite and employed in a periodic manner, resulting in non-smooth boundary conditions due to the quasi-chaotic nature of turbulent flows. This problem is often negligible, but on occasion can corrupt the LES, regularly adding subtle, meaningless structures to the data set.

To eliminate this risk, one can create a smooth inflow profile using dynamic mode decomposition (DMD), a tool commonly used in the fluids community to identify coherent structures in dynamic flows. This work demonstrates the potential of this approach for recreating fully developed turbulent flow fields and the importance of choosing correct modes. Results are discussed through standard statistical profiles and through DMD in the spatial domain to identify the growth, decay and stability of structures used in the inflow profiles.

Abstract Author(s): E.M. Cleary