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Ann. Geophys., 24, 89-95, 2006
www.ann-geophys.net/24/89/2006/
© European Geosciences Union 2006
Numerical simulation of 3-D flow around sounding rocket in the lower thermosphere
J. Kurihara1, K.-I. Oyama1, N. Iwagami2, and T. Takahashi3
1Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan
2Dept. of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
3Information Science Laboratory, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
Abstract. Numerical simulations using the Direct Simulation Monte Carlo (DSMC) method
are known to be useful for analyses of aerodynamic effects on in-situ rocket
measurements in the lower thermosphere, but the DSMC analysis of a spin
modulation caused by an asymmetric flow around the rocket spin axis has been
restricted to the two-dimensional and axially symmetric simulations in actual
sounding rocket experiments. This study provides a quantitative analysis of
the spin modulation using a three-dimensional (3-D) simulation of the asymmetric
flow with the DSMC method. Clear spin modulations in the lower thermospheric
N2 density measurement by a rocket-borne instrument are simulated
using the rocket attitude and velocity, the simplified payload structure, and
the approximated atmospheric conditions. Comparison between the observed and
simulated spin modulations show a very good agreement within 5% at around
100km. The results of the simulation are used to correct the spin
modulations and derive the absolute densities in the background atmosphere.
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