Microgravity sensitivity of typical fluid physics experiment

Rodolfo Monti, Raffaele Savino, Marcello Lappa

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

16 Citations (Scopus)
34 Downloads (Pure)


This report summarizes a number of numerical results concerning the g-jitter sensitivity and the performances of Isolation Mounts for a typical Fluid Physics experiment in the Fluid Science Laboratory of the ISS. The results corresponding to the ideal (zero-g) purely diffusive situation are compared with the real case of residual-g superimposed to g-jitters, in the presence or in the absence of ARIS. The investigated cases correspond to the predicted accelerations on the ISS according to the NASA Design Analysis Cycles (DAC3 and DAC4), and to the worst situation, in which residual-g and g-jitters are supposed to be both perpendicular to the density gradient. In this situation buoyancy effects, induced by residual-g, and thermovibrational effects, induced by high frequency periodic oscillations, are concurrent and produce the maximum disturbances of the temperature and/or of the concentration fields, compared to the ideal diffusive (zero-g) situation.
The report addresses the following relevant points that help to take decisions on the suitability of implementing an isolation mount on the ISS for these categories of experiments.
a) The exact knowledge of the real ISS microgravity environments. At the moment a number of analyses (Dynamic Analysis Cycles, DAC) are being refined according to the most recent data on the operation and on the H/W existing on board the ISS. For instance the last DACs (DAC-3 and DAC-4) present completely different scenarios for the ISS microgravity environment so much that DAC-3 would justify the introduction of the ARIS that, conversely, is not justified by DAC-4 (at least for the Columbus Orbital Facility, COF) because of the marginal improvements that could be achieved.
b) The equivalence criterion between the convective disturbances caused by the residual-g existing at different locations of the ISS (mainly due to gravity gradients and to aerodynamic drag) and the relatively high frequency g-jitter caused by on board machinery and crew operations. Establishing an equivalence between these two kinds of perturbations could allow an evaluation of the relative importance of the residual-g and of the g-jitter and may provide a clear picture of the improvements that one can expect from ARIS.
c) The benefits that one could expect from the orientation of the experiment cell with respect to the residual-g and to the g-jitter. In fact properly orienting the cell may result in benefits larger than killing all the high frequency g-jitter (by ARIS) that are likely to be present on the ISS.
d) The possibility of taking advantage of the presence of the residual-g also to simulate on ground ISS experiments. In fact one is able to reproduce on ground the same convective effects that prevail in orbit due to both residual-g and g-jitters, by means of model liquids and appropriate dimensions. Experiments on ground and on the ISS have been identified that should exhibit similar behaviour.
Original languageEnglish
Title of host publicationthe 17 th Microgravity Measurements Group Meeting, Cleveland, Ohio, 24-26 March 1998
Subtitle of host publicationNASA CP-1998-208414 (ISSN: 0191-7811)
Place of PublicationCleveland, Ohio
Number of pages15
Publication statusPublished - 1 Jul 1998
Event17th International Microgravity Measurements Group (MGMG) meeting , 1998 - Ohio Aerospace Institute, Brook Park, United States
Duration: 24 Mar 199826 Mar 1998


Other17th International Microgravity Measurements Group (MGMG) meeting , 1998
Abbreviated titleMGMG 1998
Country/TerritoryUnited States
CityBrook Park


  • microgravity
  • internantional space station
  • fluid dynamics
  • acceleration


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