PowerSPECTRUM Overview

PowerFLOW simulations produce a wealth of information--raw data about the pressure, velocity and temperature fluctuations at each fluid and surface location in the simulation at each time step. In order to tap into the wealth of information available in this data, it is necessary to sample and store data frequently in time in regions of interest within the fluid and on the surface. Exa’s PowerSPECTRUM post-processing tool provides new insight into PowerFLOW results by offering a range of calculations and options for extracting crucial diagnostic data for graphs, visualizations and animations.

PowerSPECTRUM is a tool for post-processing time-dependent data using time-series and frequency-domain analysis of data at fluid and surface measurement locations. Flow structures occurring at frequencies of interest can be isolated from the overall flow field using Fourier-based filtering.

Unsteady Aerodynamics

Many industries already benefit from the detailed turbulent flow simulation afforded by PowerFLOW. Turbulent flow is almost always accompanied by separated unsteady flow regions which produce dynamic forces, as well as drive the mean aerodynamic forces, on the vehicle or body surface. PowerSPECTRUM provides a new level of analysis into the flow structure and frequency response of unsteady flow regions and body surfaces.

• Quantify low-frequency, large scale fluid motions like vortex shedding and wake dynamics
• Examine turbulent fluctuations at higher frequencies.  Show both the energy and structure of turbulent eddies resolved within the simulation

Aeroacoustics

The audible noise created by the flow of air over a vehicle has become a driving design criterion. PowerSPECTRUM provides comprehensive analysis of PowerFLOW results on the vehicle surface, in the near-field turbulent flow regions, and in regions of acoustic propagation toward the far field. Frequency-based flow analysis methods can be used to investigate:

• Pressure fluctuation levels at the vehicle surface which can lead to noise observed by passengers;
• Radiation of acoustic wavefronts within a fluid region of interest and toward far field observers
• Coupling of shear-layer dynamics with acoustic resonance characteristics for application to sun roofs, open side windows and convertible automobiles