A novel numerical scheme for unstructured compressible large eddy simulation (LES) is developed. This method is low-dissipative and less sensitive to the quality of the computational grid and is targeted for performing large-scale, high-fidelity simulations of turbulent flows in complex configurations. The objective of this work is to introduce this method, present a rigorous validation study, and demonstrate the application to a variety of jet configurations. This technique is validated by predicting the flow and noise emitted from a single-stream pressure-matched hot supersonic jet. Nearfield flow as well as farfield noise computed using an acoustic projection method is studied and compared to experimental measurements obtained by Dr. James Bridges at NASA Glenn. Mesh refinement studies and sensitivity study on selecting the acoustic projection surface are provided. To test the method's performance in a variety of jet noise configurations, it is applied to a high bypass ratio dual-stream jet at sonic conditions, a vertical supersonic jet impinging on the ground, and a horizontal supersonic jet impinging on an angled jet blast deflector.

No abstract

We present the design and evaluation of a technique for influencing user respiration by integrating respirationpacing methods into the desktop operating system in a peripheral manner. Peripheral paced respiration differs from prior techniques in that it does not require the user's full attention. We conducted a within-subjects study to evaluate the efficacy of peripheral paced respiration, as compared to no feedback, in an ecologically valid environment. Participant respiration decreased significantly in the pacing condition. Upon further analysis, we attribute this difference to a significant decrease in breath rate while the intermittent pacing feedback is active, rather than a persistent change in respiratory pattern. The results have implications for researchers in physiological computing, biofeedback designers, and human-computer interaction researchers concerned with user stress and affect. ACM Classification: H5.2 [Information interfaces and presentation]: User Interfaces. -Graphical user interfaces. General terms: Design.

Development of concepts for reduction of jet noise has relied heavily on expensive experimental testing of various nozzle designs. For example, the design of nozzle serrations (chevron) and internal mixer/ejector nozzles have relied largely on laboratory and full-scale testing. Without a deeper understanding of the sources of high-speed jet noise it is very difficult to effectively design configurations that reduce the noise and maintain other performance metrics such as nozzle thrust. In addition, the high complexity of the flow limits the success of a parametric black-box optimization.