scholarly journals Numerical Investigation of Water Entry Problem of Pounders with Different Geometric Shapes and Drop Heights for Dynamic Compaction of the Seabed

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Mohammad Hossein Taghizadeh Valdi ◽  
Mohammad Reza Atrechian ◽  
Ata Jafary Shalkoohy ◽  
Elham Chavoshi
Keyword(s):  
Impact Velocity ◽  
Three Dimensional ◽  
Water Entry ◽  
Drop Height ◽  
Fluid Structure Interactions ◽  
Critical Height ◽  
Geometric Shapes ◽  
Model Fluid ◽  
Explicit Dynamic ◽  
Off Time

The water entry problem of three-dimensional pounders with different geometric shapes of cube, cylinder, sphere, pyramid, and cone was numerically simulated by the commercial software Abaqus, and the effects of pounder shape and drop height from the free surface of water on deepwater displacement and velocity as well as pinch-off time and depth were investigated. An explicit dynamic analysis method was employed to model fluid-structure interactions using a Coupled Eulerian-Lagrangian (CEL) formulation. The simulation results are verified by showing the computed shape of the air cavity, displacement of sphere, pinch-off time, and depth which all agreed with the experimental results. The results reveal that the drag force of water has the highest and lowest effect on cubical and conical pounders, respectively. Increasing the pounder drop height up to the critical height leads to increased pounder velocity while impacting the model bed and more than the critical drop height has a reverse effect on pounder impact velocity. Pinch-off time is a very weak function of pounder impact velocity; but pinch-off depth increases linearly with increased impact velocity.

Water Entry of a Wedge by Hydroelastic Orthotropic Plate Theory

1999 ◽  
Vol 43 (03) ◽  
pp. 180-193 ◽  
Author(s):  
Odd M. Faltinsen
Keyword(s):  
Impact Velocity ◽  
Cross Sections ◽  
Orthotropic Plate ◽  
Plate Theory ◽  
Three Dimensional ◽  
Water Entry ◽  
Natural Period ◽  
Cross Sectional ◽  
Flow Effects ◽  
The Impact

Water entry of a hull with wedge-shaped cross sections is analyzed. The stiffened platings between two transverse girders on each side of the keel are separately modeled. Orthotropic plate theory is used. The effect of structural vibrations on the fluid flow is incorporated by solving the two-dimensional Laplace equation in the cross-sectional fluid domain by a generalized Wagner's theory. The coupling with the plate theory provides three-dimensional flow effects. The theory is validated by comparison with full-scale experiments and drop tests. The importance of global ship accelerations is pointed out. Hydrodynamic and structural error sources are discussed. Systematic studies on the importance of hydroelasticity as a function of deadrise angle and impact velocity are presented. This can be related to the ratio between the wetting time of the structure and the greatest wet natural period of the stiffened plating. This ratio is proportional to the deadrise angle and inversely proportional to the impact velocity. A small ratio-means that hydroelasticity is important and a large ratio means that hydroelasticity is not important.

scholarly journals A coupled lattice Boltzmann and Cosserat rod model method for three-dimensional two-way fluid–structure interactions

AIP Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 075020
Author(s):  
Suguru Ando ◽  
Mitsuru Nishikawa ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Fluid Structure Interactions ◽  
Fluid Structure ◽  
Model Method ◽  
Cosserat Rod ◽  
Rod Model

Analysis of Mixing Efficiency in a Multi-Cut Transfermix

1995 ◽  
Vol 68 (5) ◽  
pp. 773-782 ◽  
Author(s):  
Tao Li ◽  
Hongfei Cheng ◽  
Ica Manas-Zloczower
Keyword(s):  
Three Dimensional ◽  
Mixing Efficiency ◽  
Power Law Model ◽  
Screw Extruder ◽  
Axial Pressure ◽  
Three Dimensional Flow ◽  
Single Screw ◽  
Single Screw Extruder ◽  
Model Fluid ◽  
Constant Output

Abstract Three-dimensional flow patterns of a power-law model fluid in a Multi-Cut Transfermix were calculated. A particle tracking algorithm was used to study the dynamics of mixing. Distributive mixing efficiency was quantified in terms of length stretch distributions and average values. The influence of rotational speed and axial pressure difference on mixing efficiency, under constant output was analyzed. The mixing performances in the MCT was also compared with that in a single screw extruder with the same dimensions as the entrance region of MCT and operating at the same flow rate.

scholarly journals Three-dimensional oblique water-entry problems at small deadrise angles

2012 ◽  
Vol 711 ◽  
pp. 259-280 ◽  
Author(s):  
M. R. Moore ◽  
S. D. Howison ◽  
J. R. Ockendon ◽  
J. M. Oliver
Keyword(s):  
Three Dimensional ◽  
Oblique Impact ◽  
Water Entry ◽  
Rigid Bodies ◽  
Normal Impact ◽  
Displacement Potential ◽  
Pressure Profiles ◽  
The Relationship ◽  
Wagner Theory ◽  
The Ideal

AbstractThis paper extends Wagner theory for the ideal, incompressible normal impact of rigid bodies that are nearly parallel to the surface of a liquid half-space. The impactors considered are three-dimensional and have an oblique impact velocity. A formulation in terms of the displacement potential is used to reveal the relationship between the oblique and corresponding normal impact solutions. In the case of axisymmetric impactors, several geometries are considered in which singularities develop in the boundary of the effective wetted region. We present the corresponding pressure profiles and models for the splash sheets.

Slam induced loads on a 3D bow with various pitch angles

2019 ◽  
pp. 1-18 ◽  
Author(s):  
Yiwen Wang ◽  
Weiguo Wu ◽  
Shan Wang ◽  
Carlos Guedes Soares
Keyword(s):  
Impact Velocity ◽  
Pitch Angle ◽  
Water Entry ◽  
Model Tests ◽  
Experimental Measurements ◽  
Pressure Distributions ◽  
Slamming Load

Abstract A 3D water entry of a typical bow model of River-to-Sea ship is studied experimentally. A large number of systematic experiments have been performed for the bow model with different pitch angles. Considering various pitch angles and impact velocities in the model tests, the slamming pressure distributions on the bottom of the bow are presented and discussed. The measured slamming pressures on the bow are identified in terms of the maximum slamming coefficient. The effects of the pitch angle and impact velocity on slamming pressure are discussed as well, based on the experimental measurements. It is shown that the slamming load on the bottom of the model increases as the pitch angle decreases in most cases. With a higher impact velocity, the coefficient of the maximum slamming pressure is smaller for most of the tested cases.

Effects of Heat Transfer on the Spreading and Freezing of Molten Droplets Impinging Onto Textured Surfaces: A Computational Study

2012 ◽  
Author(s):  
Mehdi Raessi ◽  
Rajkamal Sendha
Keyword(s):  
Heat Transfer ◽  
Impact Velocity ◽  
Computational Study ◽  
Three Dimensional ◽  
Quantitative Relationship ◽  
Textured Surfaces ◽  
Molten Droplets ◽  
Energy Equations ◽  
The Impact ◽  
Obstacle Height

We present our recent study on spreading and solidification of micro-droplets of alumina impacting onto patterned surfaces textured by micron-size obstacles. We employed an in-house, three-dimensional computational tool that solves the flow and energy equations and takes into account the solidification. We investigated the spreading dynamics, heat transfer, and solidification of the droplets as a function of the height and spacing of the obstacles as well as the impact velocity. The results show that, independent of the obstacle height, the droplet assumes a disk-shape geometry when the obstacles are either packed tightly or are very distanced. The results at intermediate obstacle spacings exhibit the most significant deformations, where the droplet develops long fingers. A quantitative relationship shows the collapse of the final spread diameter of the droplet normalized by the obstacle spacing when plotted against the spacing for different impact velocity as well as the obstacle height.

scholarly journals Cylindrical Smoothed Particle Hydrodynamics Simulations of Water Entry

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Kai Gong ◽  
Songdong Shao ◽  
Hua Liu ◽  
Pengzhi Lin ◽  
Qinqin Gui
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Three Dimensional ◽  
Water Entry ◽  
Surface Velocity ◽  
Governing Equations ◽  
Pressure Fields ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
Dam Break Flow

This paper presents a smoothed particle hydrodynamics (SPH) modeling technique based on the cylindrical coordinates for axisymmetrical hydrodynamic applications, thus to avoid a full three-dimensional (3D) numerical scheme as required in the Cartesian coordinates. In this model, the governing equations are solved in an axisymmetric form and the SPH approximations are modified into a two-dimensional cylindrical space. The proposed SPH model is first validated by a dam-break flow induced by the collapse of a cylindrical column of water with different water height to semi-base ratios. Then, the model is used to two benchmark water entry problems, i.e., cylindrical disk and circular sphere entry. In both cases, the model results are favorably compared with the experimental data. The convergence of model is demonstrated by comparing with the different particle resolutions. Besides, the accuracy and efficiency of the present cylindrical SPH are also compared with a fully 3D SPH computation. Extensive discussions are made on the water surface, velocity, and pressure fields to demonstrate the robust modeling results of the cylindrical SPH.

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