Lattice Boltzmann simulation of free surface flow impact on a structure

Liquid impact on a rigid wall is a common feature in the context of marine structures, as most of them are exposed continuously to breaking waves. In the present paper, a comparison and analysis of the impact load estimates obtained from free surface lattice Boltzmann (LB) simulation with the experimental measurements from available literature have been reported. Initially, two-dimensional simulation of the dam break impact on the wall is performed with two different LB models: BGK-F1: a Bhatnagar-Gross-Krook (BGK) collision operator with the force scheme of Buick and Greated [Phys. Rev. E 61, 5307 (2000)], and MRT-F2: a multiple relaxation time (MRT) operator with the force scheme of Guo et al. [Phys. Rev. E 65, 046308 (2002)]. The pressure estimates obtained from BGK-F1 over MRT-F2 are closer to the measurements, though the other key parameters, such as the waterfront evolution and the free surface profile, have not shown significant variations. Furthermore, the three-dimensional dam break simulation has been performed using BGK-F1 for three test cases: (i) impact on a wall, (ii) impact on a rectangular obstacle, and (iii) impact on a tall tower. In all the test cases, the load estimates are in agreement with the experimental measurements.

Figure 1

(a) Initial dam break setup [5] and (b) the locations of pressure probes placed at the left wall. (a) Side view; (b) pressure probes at the left wall.

Figure 2

Two-dimensional free surface evolution of BGK-F1 (first row) and MRT-F2 (second row) with experiments: (a) Ref. [5], (b) $\mathrm{\Delta }x=0.005\mathrm{m}$, (c) $\mathrm{\Delta }x=0.0025\mathrm{m}$, and (d) $\mathrm{\Delta }x=0.00125\mathrm{m}$.

Figure 3

Comparison of 3D free surface evolution (BGK-F1) with experiment [5]: (a) $H=0.3\mathrm{m}$ and (b) $H=0.6\mathrm{m}$.

Figure 4

Time evolution of water front compared with experimental measurements [5] (a) $H=0.3\mathrm{m}$ (results of other grid sizes can be found in the supplemental material [32]) and (b) $H=0.6\mathrm{m}$.

Figure 5

Time evolution of water front (BGK-F1) compared with experimental measurements [5] (a) $H=0.3\mathrm{m}$ (results of other grid sizes can be found in the supplemental material [32]), (b) $H=0.6\mathrm{m}$, and (c) evolution profile from other experiments [2, 5, 30] along with both fill levels used in the present study.

Figure 6

Comparison of pressure time histories for 2D simulation $H=0.3\mathrm{m}$ (left) (results of other grid sizes can be found in the supplemental material [32]) and $H=0.6\mathrm{m}$ (right).

Figure 7

Comparison of pressure time histories for 3D simulation along with 2D BGK-F1 time histories $H=0.3\mathrm{m}$ (left) (results of other grid sizes can be found in the supplemental material [32]) and $H=0.6\mathrm{m}$ (right).

Figure 8

Initial dam break setup [20]: (a) side view, (b) top view, and (c) obstacle.

Figure 9

Free surface evolution of dam-break flow impact on the container.

Figure 10

Evolution of water level at probes $\mathbf{H}\mathbf{2}$ and $\mathbf{H}\mathbf{4}$ for dam break impact on a container.

Figure 11

Comparison of pressure time histories for dam break impact on a container.

Figure 12

Initial dam break setup [21]: (a) side view and (b) top view.

Figure 13

Free surface evolution of dam-break flow impact on the tower.

Figure 14

Comparison between LB and experimental measurements [21]: (a) velocity probe in front of the structure, (b) force exerted on the obstacle, and (c) cumulative impulse.