Assessment of thermovibrational theory:: Application to G-jitter on the space station

The numerical modeling of the effects of g-jitter (oscillatory residual acceleration disturbances) on fluid dynamics experiments onboard the International Space Station is discussed. The aim is an assessment of the thermovibrational theory, based on the time-averaging technique and the evaluation of the orders of magnitude of all of the terms appearing in the complete equations, identifying the role and the importance of average and oscillatory terms. The identification of the most important terms in the momentum and in the energy equation is made by an a posteriori order of magnitude analysis by means of the numerical solution of the unsteady full Navier-Stokes equations. Different flow regimes are identified, and some apparent contradictions in the current literature on the effects of g-jitter are clarified. The set of reduced equations and the associated range of validity is of great potential interest for the scientific community to develop analytical and/or mixed numerical/analytical solutions that can lead to a significant reduction of the often prohibitive computational time required for the simulation of the complex phenomena under investigation.