A numerical tool has been prepared to quickly predict the overall disturban
ces for the typical Microgravity Environment (MGE) on the ISS. A reference
study case (that shows a large sensitivity to acceleration disturbances) is
identified and numerical simulations are carried out to compare the result
s of the solution of the full Navier-Stokes equations with a time-dependent
acceleration (that give the instantaneous time-dependent flow) with the so
lutions of the time-averaged field equations (Gershuni formulation), contai
ning all the g-jitter terms (like those that identify the microgravity envi
ronment of the ISS) grouped in a single parameter. The paper shows that the
overall disturbances of the thermo-fluid-dynamic field are easily evaluate
d assigning as input to the fluid-dynamic code a single (equivalent) freque
ncy g-jitter (in the direct formulation) or an overall vibrational Rayleigh
number (in the time-averaged formulation). The code is validated and appli
ed to the problem of thermodiffusion in a typical metal alloy. (C) 2001 Int
ernational Astronautical Federation. Published by Elsevier Science Ltd.