Date : To : From : Subject : 2 September , 2010 Distribution

The present document describes an approach for deriving a model of the power spectral density (PSD) for the fluctuating pressure in a turbulent flow. Ultimately, a model for compressible, transitional and fully turbulent pressure fluctuation loading to calculate a random vibration pressure field on an RB/RV during reentry conditions is sought. Both a power spectral density (PSD) as well as a probability density function (PDF) of the fluctuating pressure are required. The model summarized herein is a model for the fluctuating pressure PSD only (not a fluctuating pressure PDF), and would be an alternative (or perhaps a supplement) to the earlier “eigenvalue problem” model [10] and the “legacy” model [13].