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A key objective of the cryogenic fluid management of the spacecraft propulsion system is to develop the technology necessary for acquisition or positioning of liquid outflow or vapor venting. In this paper, numerical simulation of positive liquid acquisition is attempted by introducing reverse gravity acceleration, resulting from the propulsive thrust of auxiliary engines, which exceeds critical value for the initiation of geyser. Based on the computer simulation of flowfields during the course of fluid reorientation, six dimensionless parameters resulted in this study. It shows that these parameters hold near-constant values through the entire ranges of liquid filled levels, from 30-80%, during the course of fluid reorientation. D f 8i go h v fm Nomenclature = geyser initiation acceleration, cm/s 2 = scale flow acceleration associated with maximum velocity (crii/s 2 ), defined by Eq. (5) = diameter of propellant tank, cm = frequency of impulsive thrust, Hz = geyser initiation gravity level, go = normal Earth gravitational acceleration, 9.81 m/s 2 = average liquid height, cm = maximum liquid height, cm = height of propellant tank, cm = scale length of maximum liquid height (cm), defined byEq. (4) -average free-fall time, s = time for observing maximum flow velocity, s = liquid reaching tank bottom time, s = average free-fall velocity (cm/s), defined by Eq. (2) = free-fall velocity from maximum liquid height (cm/s), defined by Eq. (3) = maximum flow velocity, cm/s

Gravity waves are the product of Joule heating, the auroral electrojet during geomagnetic substorms, the equatorial electrojet in the thermosphere, severe thunderstorms, tornadoes, and hurricanes in the troposphere, etc. A thorough understanding of sources and sinks of gravity waves can greatly advance our knowledge concerning atmosphere‐ionosphere‐magnetosphere couplings. We have limited ourselves in this paper to discussions of couplings between the ionosphere and the troposphere during the time periods of isolated tornadoes on the stormy day of November 20, 1973. Identification of the location of wave sources for waves detected at F region ionospheric heights was attempted by using the observed characteristics of wave propagation in ray‐tracing computations. Computed locations of wave sources were then compared with conventional meteorological data. The results show that the sources of the gravity waves associated with tornadoes were always on the squall lines and near the tornado touchdown locations. The results also suggest that ionosphere‐troposphere coupling studies can contribute to our understanding of the dynamical development of severe storms.

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