Mitigation of liquid sloshing in a rectangular tank due to slotted porous screen

2020 ◽  
Vol 234 (3) ◽  
pp. 686-698
Author(s):  
Sunny Kumar Poguluri ◽  
Il-Hyoung Cho
Keyword(s):  
Free Surface ◽  
Numerical Technique ◽  
Liquid Sloshing ◽  
Tank Wall ◽  
Air Entrapment ◽  
Jet Formation ◽  
Induced Motion ◽  
Free Surface Wave ◽  
Nonlinear Free Surface ◽  
Porous Screen

Liquid sloshing inside a tank with a slotted porous screen at the center is studied based on numerical and experimental methods. Slotted screens with three different porosities (0.0964, 0.1968 and 0.3022) for two submergence depths of 1 and 2 cm have been considered. One of the main advantages of the slotted screens is that the resonance frequency of the sloshing tank can be altered and the sloshing-induced motion/load can be suppressed by energy dissipation across the porous screen. The complexities of slotted screens equipped in a sloshing tank are accompanied by wave breaking, jet formation and liquid fragmentations which are commonly seen phenomena across the porous screen. These violent free surface behaviors in a tank are studied based on numerical simulations using the incompressible turbulent model and compared with the experiments. For the numerical sloshing tank with porous screen, free surface elevation and pressure at the tank wall are in good agreement with the experimental results. The adopted numerical technique will be able to capture the nonlinear free surface wave profile, air entrapment and jet formation across the screen in agreement with the experiments. For the fully submerged screen, the lowest resonance period shifted slightly to higher values. The sloshing tank equipped with porous screen of 0.1968 for the fully submerged screen predicted lower values of the amplification factor and pressure at the tank wall compared to other cases.

3D SPH Numerical Investigation for the Sloshing Impact in LNG Tank

2013 ◽  
Author(s):  
Zhigang Bai ◽  
Jun Zhao ◽  
Wei Zhang ◽  
Weiling Wang
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Liquid Sloshing ◽  
Dynamic Responses ◽  
Sph Method ◽  
Sph Model ◽  
Lng Tank ◽  
Liquid Natural Gas

Sloshing in liquid natural gas (LNG) tankers includes extremely large deformations of the free surface. To better understand such deformations, a three-dimensional Smoothed Particle Hydrodynamics (SPH) method is developed to analyze the dynamic responses of liquid sloshing in LNG tank. The numerical model solves the Euler equation in the SPH style, the Monaghan-type artificial viscosity has been used in the current SPH model, sloshing wall boundaries were treated by improved coupling boundary pressure treatment. The numerical model is first validated against experimental data for two-dimensional and three-dimensional liquid sloshing in a LNG tank, it shows a fair agreement of overall fluid motions and hydrodynamic pressures. The fields of 3D sloshing pressure and velocity are compared for one period. Finally, the model is used to study 3D liquid sloshing in a tank with vertical baffles. The effect of the baffle on pressure and velocity is investigated and discussed. It shows that the SPH method is a natural numerical technique for coupled fluid-structure problems with large free-surface deformations.

Experimental and Numerical Study on Liquid Sloshing Dynamics with Single Vertical Porous Baffle in a Sway Excited Ship Tank

2020 ◽  
Author(s):  
Sahaj k v ◽  
Nasar Thuvanismail
Keyword(s):  
Free Surface ◽  
Boundary Element ◽  
Numerical Study ◽  
Excitation Frequency ◽  
Boundary Element Methods ◽  
Liquid Sloshing ◽  
Shake Table ◽  
Natural Period ◽  
Rectangular Tank ◽  
Porous Screen

<p>Liquid motion in partially filled tanks may cause large structural loads if the period of tank motion is close to the natural period of fluid inside the tank. This phenomenon is called sloshing. Sloshing means any motion of a free liquid surface inside a container. The effect of severe sloshing motion on global seagoing vessels is an important factor in safety design of such containers. In order to examine the sloshing effects, a shake table experiments were conducted for different water fill depth of aspect ratio 0.163, 0.325 and 0.488. The parametric studies were carried out to show the liquid sloshing effects in terms of slosh frequencies, maximum free surface elevation and hydrodynamic forces acting on the tank wall. Sloshing oscillation for the excitation frequency f<sub>1</sub>, f<sub>2</sub>, f<sub>3</sub>, f<sub>4 </sub>and f<sub>5</sub> are observed and analysed. The excitation frequencies is varied between 0.4566 Hz to 1.9757 Hz and constant amplitudes of 7.5mm was adopted. The movement of fluid in a rectangular tank has been studied using experimental approach and different baffle configurations were adopted for analysing the sloshing oscillation, natural frequencies and variation in wave deflection. The adopted porosities in the present study is 15% – 25 %. Porous screen is placed inside the tank at L/2 location and study is extended for single porous screen for better wave energy absorption. Capacitance wave probes have been placed at tank ends to record the free surface water elevation. Load cells are used to measure the sloshing force inside the tank. Linear variable displacement transducers is used to measure the displacement of shake table. In the present study single porous screen under the action of wave were analysed to understand the wave control performance due to porosity parameters. A boundary element model is developed to calculate problems of wave interaction with a porous screen structure. The numerical results from the present boundary element methods (BEM) are compared with series of experiments conducted in a rectangular tank with various baffle porosities and submerged depths.</p><p> </p>

Peculiarities of the Power Hydrocannon Operation

2003 ◽  
Author(s):  
G. A. Atanov ◽  
A. N. Semco ◽  
O. P. Petrenko ◽  
E. S. Geskin ◽  
V. Samardzic ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Technique ◽  
Design Parameters ◽  
Jet Formation ◽  
Pressure Fields ◽  
Fluid Jets

The paper is concerned with improvement of the devices for formation of super high-speed fluid jets termed hydro cannon. Two modes of the energy injection into the fluid (the piston impact and the powder explosion) are considered and advantages of the use of the gunpowder are determined. A numerical technique for prediction of the jet formation, developed previously by one of the authors is applied for description of the velocity and pressure fields within the hydro cannon. Effect of the design parameters on the fluid acceleration is explored and suggestions for improvement of the hydro cannon design are made.

Response of Liquid in Cylindrical Tank with Rigid Annual Baffle Considering Damping Effect

2011 ◽  
Vol 255-260 ◽  
pp. 3687-3691 ◽  
Author(s):  
Jia Dong Wang ◽  
Ding Zhou ◽  
Wei Qing Liu
Keyword(s):  
Free Surface ◽  
Dynamic Response ◽  
Potential Function ◽  
Natural Frequencies ◽  
Damping Ratio ◽  
Cylindrical Tank ◽  
Generalized Coordinates ◽  
Damping Effect ◽  
Total Potential ◽  
Free Surface Wave

Sloshing response of liquid in a rigid cylindrical tank with a rigid annual baffle under horizontal sinusoidal loads was studied. The effect of the damping was considered in the analysis. Natural frequencies and modes of the system have been calculated by using the Sub-domain method. The total potential function under horizontal loads is assumed to be the sum of the tank potential function and the liquid perturbed function. The expression of the liquid perturbed function is obtained by introducing the generalized coordinates. Substituting potential functions into the free surface wave conditions, the dynamic response equations including the damping effect are established. The damping ratio is calculated by Maleki method. The liquid potential are obtained by solving the dynamic response equations of the system.

Discussion on Venkat & Spaulding: “Numerical Simulation of Nonlinear Free-Surface Flows Generated by a Heaving Body of Arbitrary Cross Section”

1991 ◽  
Vol 35 (03) ◽  
pp. 250-253
Author(s):  
Apostolos Papanikolaou
Keyword(s):  
Free Surface ◽  
Cross Section ◽  
Euler Method ◽  
Free Surface Flows ◽  
Arbitrary Cross Section ◽  
Circular Cylinders ◽  
Published Data ◽  
The Time Domain ◽  
Heave Motion ◽  
Nonlinear Free Surface

A method has been presented recently by Venkat and Spaulding to solve the nonlinear boundary-value problem of oscillating two-dimensional cylinders of arbitrary cross section on the free surface of a fluid. The method relies on a second-order finite-difference technique with a modified Euler method for the time domain and a successive over-relaxation procedure for the spatial domain. The authors compare their numerical results with those of other authors (theoretical and experimental), as they have published data for specialized forms like a wedge, circular cylinders, and ship-like sections in forced heave motion (references [4] to [7] and [22], [23] of the paper).

Surface Ship Total Resistance Prediction Based on a Nonlinear Free Surface Potential Flow Solver and a Reynolds-Averaged Navier-Stokes Viscous Correction

2007 ◽  
Vol 51 (01) ◽  
pp. 47-64
Author(s):  
James C. Huan ◽  
Thomas T. Huang
Keyword(s):  
Free Surface ◽  
Surface Potential ◽  
Potential Flow ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Total Resistance ◽  
Flow Solver ◽  
Resistance Prediction ◽  
Nonlinear Free Surface

A fast turnaround and an accurate computational fluid dynamics (CFD) approach for ship total resistance prediction is developed. The approach consists of a nonlinear free surface potential flow solver (PShip code) with a wet-or-dry transom stern model, and a Reynolds-averaged Navier-Stokes (RANS) equation solver that solves viscous free surface flow with a prescribed free surface given from the PShip. The prescribed free surface RANS predicts a viscous correction to the pressure resistance (viscous form) and viscous flow field around the hull. The viscous free surface flow solved this way avoids the time-consuming RANS iterations to resolve the free surface profile. The method, however, requires employing a flow characteristic-based nonreflecting boundary condition at the free surface. The approach can predict the components of ship resistance, the associated wave profile around the hull, and the sinkage and trim of the ship. Validation of the approach is presented with Wigley, Series 60 (CB = 0.6), and NSWCCD Model 5415 hulls. An overall accuracy of ±2% for ship total resistance prediction is achieved. The approach is applied to evaluating the effects of a stern flap on a DD 968 model on ship performance. An empirical viscous form resistance formula is also devised for a quick ship total resistance estimate.

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