One of the goals of experimental fluid flow is to verify large computational models. This requires the remote measurement of the 3-D velocity vector within a flow. This project uses twin frequency-doubled YAG lasers to record two holograms of the fluid flow at two instants in time. The complete velocity field is then reconstructed by performing 3-D correlations of tracer particles within single volume elements (typically 1 mm³).

Advanced optical interconnections based on parallel space division multiplexing using a fiber ribbon or wavelength division multiplexing using multiple wavelengths within a single fiber require new techniques to measure and model performance. These techniques are being developed because the aggregate data rates through these parallel spaces exceed 15 Gbits/s. We are currently developing testing methodologies and equipment to test and model the performance of these high-speed data links.

Current models of ozone depletion over the Antarctic predict that some of the major chemical mechanisms occur on the surface of polar stratospheric clouds (PSCs). In addition, the energy-coupling mechanisms from the lower to the upper atmosphere over the Antarctic are not well understood. We are currently deploying an advanced lidar system at the South Pole that is capable of measuring characteristics of the morphology of the PSCs and also to measure upper atmospheric wave activity using Na as a tracer.

The noise from testing and training with large weapons is a problem around military installations worldwide. This research focuses on modeling, predicting, and mitigating the finite-amplitude pressure pulse near a weapon by means of an absorptive surface and other devices. In particular, we are concerned with modeling the large transient pressure-pulse wave as it propagates and interacts with an impedance surface, and with modeling the impedance surface.

Basic theoretical and experimental studies are undertaken in the reduction of sound pressure levels in the Earth's atmosphere as produced by various sound sources. The problem is complicated by the inhomogeneous and anisotropic nature of the atmosphere and by the presence of the absorbing ground and other obstacles. Methods of noise mitigation are proposed and investigated, with the goal of improving the acoustical noise environments of airports and military training facilities.