ABSTRACT
The alternation of a physical system between two phases or states is herein referred to as intermittency. Examples of intermittent phenomena abound in applications and include the transition from laminar to turbulent flow over a flight vehicle and the presence of imperfections within material microstructure. It is shown that intermittent phenomena of this type can be modeled by two-state random fields with piecewise constant samples; we refer to the states of the random field as "off" and "n" or, equivalently, as 0 and 1. These random fields can be calibrated to available information, which we assume consists of: (1) the marginal probability that the state of the system is "n"; and (2) the average number of fluctuations between states that occur within a bounded region. The proposed model is defined by a sequence of pulses of prescribed shape and unit magnitude, located at random (Poisson) points within a bounded domain. For illustration, we use this model to represent the location and movement of turbulent bursts during the transition from laminar to turbulent flow over the surface of a flight vehicle, and assess the resulting random vibration response of the structure during the transition event.
Keywords: Boundary Layer Transition, Intermittency, Poisson Random Fields, Random Vibration.
