CFD-MHD Project Research Highlights

Simulation of Bar-driven Spirals in Galactic Disks

It is well known that spiral density waves can be generated by a rotating bar through a resonance excitation mechanism. Associated with these waves is the angular momentum transport between the bar and the disk. As waves attenuated by viscosity, the angular momentum will be deposited in the disk. This will cause the disk matter moving inward or outward, depending respectively on whether the angular momentum carried by the waves is negative or positive. The re-distribution of the matter of this kind in the central gas-dust disk is recognized to be particularly important, since it provides a mechanism of fueling AGN and starburst ring activities. The morphology and dynamics of a resonantly excited disk can be calculated analytically by non-linear asymptotic methods in a steady state limit. However, the evolution of the disk cannot be achieved unless we solve the full non-linear equations in time.

On this webpage, we present numerical simulations of the disk evolution, using the relaxation code we develop, for the following three cases: spiral waves are generated by a bar.

• Case 1: at the outer inner Lindblad resonance (OILR) 1.5 Kpc
• Case 2: 3 Kpc-arm, single Lindblad resonance. OLR occures at 3 Kpc
• Case 3: 3 Kpc-arm, double Lindblad resonance. OLR occures at 3 Kpc and OILR occures at 0.7 Kpc.
• All of the results are computed in polar coordinates without self-gravitation.

Please click on the images for animation!!!