Origin of asymmetric ROE velocity-dispersion peaks

Determine the origin of the one-sided peaks in the root-mean-square meridional dust-velocity distribution produced by the ROE Riemann solver at heights of approximately 0.03 AU and above in the global streaming-instability simulations.

Background

The simulations show that the ROE solver produces a strong, one-sided peak in the root-mean-square meridional dust-velocity distribution at heights where the dust density is already strongly reduced. The authors identify these peaks as potentially important for understanding differences in dust settling and vertical structure, but do not determine their physical or numerical origin.

References

The origin of these peaks remains an open question for future work.

— A comparison between particle and fluid approaches for streaming instability in global patch simulations  (2610.09575 - Ostertag et al., 7 Oct 2026) in Section 3.2, “Influence of the Riemann Solver”

Whether and how vorticity explains the difference in dust settlement is also unclear, and future research on this aspect is necessary.

— A comparison between particle and fluid approaches for streaming instability in global patch simulations  (2610.09575 - Ostertag et al., 7 Oct 2026) in Section 4.1, “Midplane dust density component”