Multipole moments
SEREN uses a Barnes-Hut tree (Barnes & Hut 1986) to efficiently calculate gravitational forces for all SPH particles, as opposed to an expensive summation over all particles. In order to improve both the accuracy and the efficiency of the cell approximation in the tree, we add higher order multipole moments to the gravitational force calculation. We test here i) the accuracy of the tree with and without the higher order multipole moment terms, and ii) the obtained accuracy compared to the cpu time taken to determine the most optimal choice of the multipole moment order.
GEO1-NBODY
- 3-dimensions
- Barnes-Hut tree gravity
- No kernel-softened gravity
- Geometric cell opening criterion
- Monopole-only, quadrupole and octupole expansions
EIGEN1-NBODY
- 3-dimensions
- Barnes-Hut tree gravity
- No kernel-softened gravity
- Eigenvalue MAC
- Quadrupole and octupole expansions