Abstract

The analysis of liquid sloshing remains a challenging computational mechanics topic due to its complex underlying physics. The rapid simulation of sloshing problems requires accurate modelling of two-phase fluid dynamics and sloshing impacts on solid tank boundaries by suitable Flexible Fluid Structure Interaction (FFSI) models. This paper presents a hydroelastic model for the prediction of sway induced sloshing loads on flexible trapezoidal and rectangular tanks. Tank walls and a vertical baffle in way of the mid span of the tank bottom are idealized by Timoshenko beam structural dynamics. Hydroelastic analysis is enabled by a Boundary Element Method (BEM) that couples tank wall and baffle structural dynamics with free surface hydrodynamics to evaluate excitation forces and peak hydrodynamic pressures in way of the tank perimeter. Results show that for the case study presented accounting for the influence of hydroelasticity in a rectangular tank may lead to decrease of free surface oscillations and peak pressure by 20%. This is because the dynamics of tank flexibility are coupled with the angular frequency of the sway motion. These benefits amplify further for the case of trapezoidal tank designs for which the free surface and pressure of the trapezoidal tank with lateral angle θ=80° are decreased relative to the rectangular one by about 80% and 65%, respectively.

Highlights

  • Liquid tanks are commonly used as storage vessels for various liquids transported by the shipping, power and processing industries

  • The assessment accounted for two key criteria namely: (i) the maximum water free surface oscillation of a node on the water free surface in contact with right hand sidewall of the tank, and (ii) the maximum hydrodynamic pressure on point A on the tank perimeter

  • Displacement of a node on the water free surface in contact with right hand sidewall (η), dynamic pressure exerted on point A were calculated for rigid and flexible tanks, and the results are shown in Figs. 11 and 12, respectively

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Summary

Introduction

Liquid tanks are commonly used as storage vessels for various liquids transported by the shipping, power and processing industries. The recent study by, Saghi et al [29] using RANS CFD demonstrated that the use of oblique perforated baffles may significantly reduce sway induced tank sloshing dynamics in rectangular liquid storage tanks when entropy effects are taken under consideration. Observations are confirmed by the work of Ning et al [30] who devel­ oped and validated a higher order BEM to idealize the effect of the vertical baffles on the severity of sloshing loads for the case of a 2D rectangular storage tank under the influence of the coupled horizontal and vertical motions. Sanapala et al [33] simulated parametric liquid sloshing in a horizontally baffled rectangular container They showed that under seismic excitations the effect of baffle width may be less significant than the baffle location in terms of reducing water free surface oscillations.

Theory
Calculate of the perimeter pressure on the tank walls and baffle
Hydroelastic modelling
Model calibration
Results
The influence of sway properties
The influence of the tank geometry
Comparison of the flexible trapezoidal and baffled rectangular tanks
Conclusions
Full Text
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