# Isotropy and spurious currents in pseudo-potential multiphase lattice Boltzmann models

## TL;DR

This paper investigates the causes of spurious currents in multiphase lattice Boltzmann models, highlighting limitations of increasing isotropy and proposing a new implementation to better suppress these artifacts.

## Contribution

It introduces a consistent implementation that more effectively reduces spurious currents and clarifies the limitations of isotropy enhancement in eliminating them.

## Key findings

- Higher isotropy alone cannot eliminate certain low-level spurious currents.
- A new implementation improves suppression of spurious currents.
- Theoretical analysis shows the importance of local hydrostatic balance.

## Abstract

The spurious currents observed in multiphase flow simulations with pseudo-potential lattice Boltzmann (LB) models are usually understood to be the result of the lack of isotropy of the model-generated interaction force between phases. Remedies have been proposed to utilize larger stencils to compute the interaction force with higher orders of isotropy. In this short communication, we point out the incompleteness in the current understanding and propose a new consistent implementation to more effectively suppress the spurious currents. We also demonstrate theoretically that certain low-level spurious currents cannot be eliminated by increasing isotropy if the local hydrostatic balance inside the diffuse interface is not established in the LB models.