Wave runup simulations using Lagrangian blocks on Eulerian mesh

Altai

2017

Environ Fluid Mech

Self Cite

A two-dimensional inviscid model of the gravity-current head produced by the release of a relatively small volume of dense fluid from behind a tall lock gate is constructed by Lagrangian block simulation. Three numerical experiments are conducted for the lock's height-to-length aspect ratios H/L o = 8, 4 and 2. The front speeds obtained by the simulations agree with the laboratory observation for a similar range of aspect ratios. The floor velocity in the wake behind these heads is found to be greater than their front speed. The high floor velocity is caused by the impingement of the coherent wake vortex on the floor. It is a condition that permits these gravity-current heads to maintain their structural integrity so that the fine sediments can travel with the head over long distances on the ocean floor. The structural coherence of the current head depends on the lock aspect ratio. The gravity-current head produced by the release from the lock with the highest aspect ratio of H/L o = 8 is most coherent and relatively has the greatest floor velocity and the least trailing current behind the head.Keywords Gravity-current head Á Coherent wake vortex Á 2D inviscid model Á Lagrangian block advection Á Streamfunction and vorticity formulation

Section: Energy Conservation and Computational Errormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A two-dimensional inviscid model of the gravity-current head by Lagrangian block simulation

Altai

2017

Environ Fluid Mech

Self Cite

“…In the present simulation of the solitary waves, the friction coefficient of the hydrodynamically smooth surface is calculated using a formula given in a previous paper by Tan & Chu (2009a). The initial location of the solitary waves is located in a position as described in Synolakis (1986) and in Tan & Chu (2010a). Typical simulated runup depth and velocity profiles were presented in the previous paper.…”

Section: Solitary-wave Runupmentioning

confidence: 99%

Regular Periodic Wave Runup and Overtopping Simulations by Lagrangian Blocks

Tan

Int. Conf. Coastal. Eng.

2011

Self Cite

Wave runup and overtopping of truncated beaches have been simulated using the method of Lagrangian Block Hydrodynamics (LBH). Instead of interpolation, which causes numerical oscillations, the fluxes through the face of the finite-volume in the LBH method are determined by the advection of the blocks. Negative water depth is not possible and the computation is unconditionally stable as the momentum is updated by the re-construction of the blocks. The accuracy of the method is evaluated using (i) the exact solution of the collapsing bore and (ii) the available laboratory data of the solitary waves as the benchmarks. The numerical simulations carried out for regular periodic waves cover a wide range of wave steepness and beach slopes taking advantage of the inherent shock-capturing and shoreline-tracking capabilities of the LBH method.

“…Altai (2001, 2002) used blocks of fluid and Lagrangian advection of the blocks to conduct turbulence simulations in a streamfunction and vorticity formulation. Tan and Chu (2009a, 2009b, 2010 extended the Lagrangian blocks advection (LBA) method for one-dimensional (1D) simulation of the waves in shallow waters using the primitive variable formulation. The present LBA method uses the real fluids as the computational elements.…”

Section: Introductionmentioning

confidence: 99%

Flood wave dynamics using Lagrangian block advection

Tan

2011 Fourth International Conference on Modeling, Simulation and Applied Optimization

2011

Self Cite

Flood wave dynamics simulations are determined by a robust and accurate Lagrangian block advection (LBA) scheme that can track the dry-and-wet interface and capture the shocks without using any slope limiter to control the numerical oscillations. Two series of challenging numerical problems are considered using the LBA. First, computations are carried out for water waves in a parabolic bowl. The wetting-and-drying interface on the surface of the bowl is tracked by the LBA method with absolute computational stability. The accuracy of the LBA method is verified by the convergent of the numerical solution to an exact solution. Finally, the LBA method is applied to carry out a series of flood wave simulations, which have closely reproduced the data obtained from the laboratory experiments.