# A comparative study of immersed boundary method and interpolated bounce-back scheme for no-slip boundary treatment in the lattice Boltzmann method: Part II, turbulent flows

## TL;DR

This study compares immersed boundary and interpolated bounce-back schemes for no-slip boundary treatment in turbulent lattice Boltzmann simulations, highlighting their relative accuracy and limitations in complex turbulent flows.

## Contribution

It provides a detailed comparison of these boundary treatments in turbulent flows, revealing the limitations of the immersed boundary method in local velocity gradient computation.

## Key findings

- Both schemes yield accurate turbulent statistics with sufficient resolution.
- Immersed boundary method underestimates dissipation near particle surfaces.
- Interpolated bounce-back scheme performs reliably in complex turbulent flows.

## Abstract

In the first part of this study, we compared the performances of two categories of no-slip boundary treatments, i.e., the interpolated bounce-back schemes and the immersed boundary methods in a series of laminar flow simulations within the lattice Boltzmann method. In this second part, these boundary treatments are further compared in the simulations of turbulent flows with complex geometry to provide a next-level assessment of these schemes. Two non-trivial turbulent flow problems, a fully developed turbulent pipe flow at a low Reynolds number, and a decaying homogeneous isotropic turbulent flow laden with a large number of resolved spherical particles are considered. The major problem of the immersed boundary method revealed by the present study is its incapability in computing the local velocity gradients inside the diffused interface, which can result in significantly underestimated dissipation rate and viscous diffusion locally near the particle surfaces. Otherwise, both categories of the no-slip boundary treatments are able to provide accurate results for most of turbulent statistics in both the carrier and dispersed phases, provided that sufficient grid resolutions are used.