Chapter 17. Drag on a Gravitating Body
Open Access
- 1 January 1988
- journal article
- Published by Oxford University Press (OUP) in Progress of Theoretical Physics Supplement
- Vol. 96, 196-210
- https://doi.org/10.1143/ptps.96.196
Abstract
In the growing process of planetesimals and protoplanets, the magnitude of gas drag on them plays important roll. The drag coefficient is expected to depend significantly on the gravitational force of the travelling astronomical bodies. The purpose of this paper is to clarify how the drag on the bodies depend on the gravitational force for the correct estimation of the time scale of planetary growth. Numerical simulations are performed for viscous flows around a gravitating sphere with mass M*, radius r0 and constant velocity V∞. For subsonic velocity, the drag coefficient Ct depends on the square of Γ ( = GM*/r0V∞2) for low Γ, and linearly on it for higher Γ. In the case of supersonic velocity, the dependence of Ct on Γ is same as that given by hypersonic approximations, or Ct ∝ Γ2.Keywords
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