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Artificial Viscosity and the Simulation of Fragmentation

Published online by Cambridge University Press:  25 April 2016

R.A. Gingold
Affiliation:
Mount Stromlo and Siding Spring Observatories
J.J. Monaghan
Affiliation:
Department of Mathematics, Monash University

Extract

Recent numerical experiments (Norman et al. 1980), which simulate the axisymmetric collapse of a rotating, self gravitating cloud, show that spurious angular momentum transport can seriously affect the evolution of the cloud. In particular, it may determine if a ring-like density enhancement will occur. The spurious angular momentum transport can arise either from an explicit artificial viscosity, which might be required if shocks occur, or from an implicit viscosity due to truncation errors in the difference equation approximation to the exact equations. In donor cell schemes like those used by Tohline (1980) and Boss (1980) spurious angular momentum transport is due to truncation errors in the difference equations. For axisymmetric problems the errors are usually not serious since the typical length of a cell in the computational grid is very much less than the length scale of the cloud. We would expect the errors to be much greater when fragmentation occurs because the length scale of a fragment may only be comparable to that of three or four cells.

Type
Contributions
Copyright
Copyright © Astronomical Society of Australia 1982

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References

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