3:45 PM - 4:00 PM
[PPS07-14] Numerical simulations of the collision of dust aggregates with viscous dissipation
Keywords:dust aggregate, collision, fragmentation
Understanding the collisional growth and fragmentation of dust aggregates in protoplanetary disks is essential to investigate how planets formed. The collisional behavior of dust aggregates has been investigated by many laboratory experiments and numerical simulations (e.g., Blum & Wurm 2008, Wada et al. 2009, Hasegawa et al. 2021).
In previous numerical simulations, the interparticle interaction within the aggregate is calculated based on the contact theory of adhesive elastic spheres (JKR theory). The effect of viscous energy dissipation during the collision is usually not taken into account, and even in calculations where it is taken into account, the effect on the results has not been investigated quantitatively.
However, the sticking velocities for ice and silica particles reported from laboratory experiments are larger than those estimated from JKR theory, suggesting that viscous energy dissipation plays an important role during particle collision (e.g., Krijt et al. 2013, Gundlach & Blum 2015, Arakawa & Krijt 2021). Thus, we investigate the effect of viscous energy dissipation on the collisional behavior of dust aggregates using numerical simulations.
In this study, we performed numerical simulations of collisions of two aggregates consisting of ice particles with a radius of 0.1 micron with different collision velocities, collision angles, and viscous drag force. The simulation code used in this study is based on the code develoved by Wada et al. (2009). The sizes of the two colliding aggregates were both 50,000 particles, and the initial shape of aggregates were prepared using ballistic particle−cluster aggregation.
Our numerical simulations revealed that the maximum velocity for collisional growth of dust aggregates is about 50 m/s and it hardly depends on the viscous drag force. We also analysed the velocities of the constituent particles during the collision, and found that even when two aggregates collide with a relative velocity of about 50 m/s, the normal component of the relative velocity of the two particles in contact is typicaly 1 m/s or less. The results suggest that the collisional growth of aggregates is almost independent of the viscous drag force which is proportional to the interparticle velocity.
In previous numerical simulations, the interparticle interaction within the aggregate is calculated based on the contact theory of adhesive elastic spheres (JKR theory). The effect of viscous energy dissipation during the collision is usually not taken into account, and even in calculations where it is taken into account, the effect on the results has not been investigated quantitatively.
However, the sticking velocities for ice and silica particles reported from laboratory experiments are larger than those estimated from JKR theory, suggesting that viscous energy dissipation plays an important role during particle collision (e.g., Krijt et al. 2013, Gundlach & Blum 2015, Arakawa & Krijt 2021). Thus, we investigate the effect of viscous energy dissipation on the collisional behavior of dust aggregates using numerical simulations.
In this study, we performed numerical simulations of collisions of two aggregates consisting of ice particles with a radius of 0.1 micron with different collision velocities, collision angles, and viscous drag force. The simulation code used in this study is based on the code develoved by Wada et al. (2009). The sizes of the two colliding aggregates were both 50,000 particles, and the initial shape of aggregates were prepared using ballistic particle−cluster aggregation.
Our numerical simulations revealed that the maximum velocity for collisional growth of dust aggregates is about 50 m/s and it hardly depends on the viscous drag force. We also analysed the velocities of the constituent particles during the collision, and found that even when two aggregates collide with a relative velocity of about 50 m/s, the normal component of the relative velocity of the two particles in contact is typicaly 1 m/s or less. The results suggest that the collisional growth of aggregates is almost independent of the viscous drag force which is proportional to the interparticle velocity.