sofia.field.neighbour_sum

class sofia.field.neighbour_sum.NeighbourSum(*args)

Bases: Function

Sum a per-pair expression over the neighbours of each particle.

Parameters:

  • expr – Per-pair expression. field is the value at the particle itself, field.neighbour the value at the neighbour. Can be scalar or vector.

  • pos – Particle position, determines which particles count as neighbours. Only pairs closer than the domain’s smoothing_length contribute to the sum.

  • exclude_self – If True, skip the particle itself.

property cutoff: Basic

Condition for a neighbour to contribute to the sum.

A neighbour contributes if it is closer than smoothing_length to the particle.