Multiscale Lagrangian-Eulerian Algorithm for Determining the Vorticity Confinement Term for Rotorcraft Computational Fluid Dynamics (CFD) Computations

This SBIR Phase I project proposes to develop a multi-scale computational algorithm to determine the vorticity confinement term for rotorcraft Computational Fluid Dynamics (CFD) computations. Similar to the Large Eddy Simulation approach, the proposed approach simulates the large scales in the flow field and models the unresolved small scales like the tip vortices in the computations. The large scales are simulated using the Eulerian approach while the unresolved small scales are modeled using the Lagrangian approach. The effects of the unresolved small scales are included into the governing equations as the Vorticity Confinement terms. As a result, one is able to perform a rotorcraft CFD computation on a regular CFD grid without excessive numerical diffusion of the tip vortices. A feasibility study will be performed during Phase I to demonstrate the validity of the proposed algorithm for preserving the rotor tip vortex structure. Only after the success of the Phase I feasibility study, it is meaningful to further refine and demonstrate the methodology in Phase II.