Non-equilibrium extrapolation method in the lattice Boltzmann simulations of flows with curved boundaries (non-equilibrium extrapolation of LBM)

The fraction of the intersected link in fluid region is an important parameter in non-equilibrium extrapolation method (NEM) in the lattice Boltzmann study since the NEM adopts different extrapolation schemes when the fraction reaches a critical value. In the present study, effect of the critical value of the fraction on the lattice Boltzmann simulations of flows with curved boundaries is investigated. The flows around a single cylinder and two parallel-placed cylinders under uniform incoming streaming are chosen as typical cases. For these given flows, small critical value of the fraction causes the lattice Boltzmann simulation to suffer severe numerical instability. Moreover, the numerical results also show that large critical value of the fraction can result in more accurate numerical results for flows under large Reynolds numbers, while the numerical accuracy is almost independent of the critical value for flows under small Reynolds numbers.