Description:
OBJECTIVE: To develop, verify and validate first principles based models for the prediction of the strong interactions between multiple vortices and between vortices and encountered structures. DESCRIPTION: Modeling these strong vortex interactions can be challenging because of the initially unknown trajectories that vortices may take due to interactions. Modeling can also be challenging due to the requirement for high computational resolution to prevent spurious numerical dissipation and diffusion of the vorticity. In light of these factors, we seek novel computational methods for accurate modeling of the interaction of multiple vortices with each other and their interaction with encountered structures. The flow field, existing internal to these vortices, is of particular interest including velocities, pressures and vorticity distributions. PHASE I: Develop preliminary computational models of the strong interaction of multiple vortex structures with each other and models of the interaction of vortices with encountered structures. This effort should address vortex stretching due to strong vortex interactions and the resultant flow fields. Identify critical hardware and software components. PHASE II: Demonstrate the computational models of the strong interactions of multiple vortex structures with each other and the strong interactions of vortices with encountered structures. Verify and validate the vortex interaction model with available experimental data and analytic results provided by the Navy. Employ the model to examine situations of Navy interest and the potential effects of vortex core size, vortex strength, and vortex geometry. Work with the Navy to determine what additional variables are required for a fully developed model. PHASE III: If the Phase II is successful, the company will be expected to demonstrate a fully developed computational model and conduct the validation of the fully developed multiple vortex structure models and models of the interaction of vortices with encountered structures. The company will verify hardware and software components needed to transition to commercial low-rate production for Navy and private sector applications. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial benefits include the potential ability to improve model lift interference effects, and the interaction of vortex structures with other vessel structures (e.g. vortex/rudder interactions), both of which would be of interest to commercial shipbuilders and operators. REFERENCES: 1. Chang, N., j. Choi, R. Yakushuji, and S.L. Ceccio, (2011), Cavitation inception during the interaction of a pair of counter-rotating vortices, Physics of Fluids, (in press) 2. Chang, N. and S.L. Ceccio, (2011), The acoustic emissions of cavitation bubbles in stretched vortices, Journal of the Acoustical Society of America, Vol. 130, No. 5, pp 3209-3219
