Numerical Simulation of Water-Entry and Sedimentation of an Elliptic Cylinder Using Smoothed-Particle Hydrodynamics Method

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Roozbeh Saghatchi ◽  
Jafar Ghazanfarian ◽  
Mofid Gorji-Bandpy
Keyword(s):  
Free Surface ◽  
Smoothed Particle Hydrodynamics ◽  
Elliptic Cylinder ◽  
Water Entry ◽  
The Body ◽  
Numerical Code ◽  
Sph Method ◽  
Navier Stokes Equation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This paper studies the two-dimensional water-entry and sedimentation of an elliptic cylinder using the subparticle scale (SPS) turbulence model of a Lagrangian particle-based smoothed-particle hydrodynamics (SPH) method. The motion of the body is driven by the hydrodynamic forces and the gravity. The present study shows the ability of the SPH method for the simulation of free-surface-involving and multiphase flow problems. The full Navier–Stokes equation, along with the continuity equation, have been solved as the governing equations of the problem. The accuracy of the numerical code is verified using the case of the water-entry and exit of a circular cylinder. The numerical simulations of the water-entry and sedimentation of the vertical and horizontal elliptic cylinder with the diameter ratio of 0.75 are performed at the Froude numbers of 0, 2, 5, and 8, and the specific gravities of 0.5, 0.75, 1, 1.5, 1.75, 2, and 2.5. The effect of the governing parameters and vortex shedding behind the elliptic cylinder on the trajectory curves, velocity components within the flow field, rotation angle, the velocity of ellipse, and the deformation of free-surface have been investigated in detail.

Modeling Fuel Injection in Gas Turbines Using the Meshless Smoothed Particle Hydrodynamics Method

2013 ◽  
Author(s):  
S. Braun ◽  
C. Höfler ◽  
R. Koch ◽  
H.-J. Bauer
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Numerical Code ◽  
Test Cases ◽  
Jet Engines ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Extensive Experimental Data

For predicting primary atomization a numerical code has been developed based on the Lagrangian Smoothed Particle Hydrodynamics (SPH) method. The advantage of this approach is the inherent interface advection. In contrast to commonly used grid based methods such as the Volume of Fluid (VoF) or Level Set method there is no need for costly and approximative interface tracking or reconstruction techniques which are required to avoid interface diffusion. It has been demonstrated by various test cases that the SPH method is capable to correctly predict single — as well as multiphase flows including the effect of surface tension. The goal of this work is to further develop the methodology with the intention to simulate primary atomization within airblast atomizers of jet engines. The authors present two test cases relevant for the simulation of primary atomization. The shear-driven deformation of a fuel droplet in a gaseous flow has been investigated and compared to data from literature. Moreover, the liquid film disintegration at the trailing edge of a planar prefilming airblast atomizer has been studied. The geometry has been derived from an existing test rig, where extensive experimental data have been acquired. Resulting droplet sizes and shear-off frequencies for different geometrical setups have been analyzed and compared to the experiment. The results reveal the promising performance of this new method for predicting primary atomization.

scholarly journals IMPROVED SMOOTHED PARTICLE HYDRODYNAMICS WITH RANS FOR FREE-SURFACE FLOW PROBLEMS

2012 ◽  
Vol 09 (01) ◽  
pp. 1240001 ◽  
Author(s):  
J. R. SHAO ◽  
M. B. LIU ◽  
X. F. YANG ◽  
L. CHENG
Keyword(s):  
Free Surface ◽  
Smoothed Particle Hydrodynamics ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Computational Accuracy ◽  
Sph Method ◽  
Flow Problems ◽  
Kernel Gradient Correction ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This paper presents an implementation of an improved smoothed particle hydrodynamics (SPH) method for numerical simulation of free-surface flow problems. The presented SPH method involves two major modifications on the traditional SPH method: (1) kernel gradient correction (KGC) and density correction to improve the computational accuracy in particle approximation and (2) RANS turbulence model to capture the inherent physics of flow turbulence. In the simulation, artificial compressibility for modeling incompressible fluid and ghost particles for treating solid boundaries are both applied. The presented SPH has been applied to two dam-breaking problems. We demonstrated that the presented SPH method has very good performance with more accurate flow patterns and pressure field distribution.

Numerical Investigation on the Water Entry of Convex Objects Using a Multiphase Smoothed Particle Hydrodynamics Model

2017 ◽  
Vol 15 (02) ◽  
pp. 1850008 ◽  
Author(s):  
L. Zou ◽  
G. X. Zhu ◽  
Z. Chen ◽  
Y. G. Pei ◽  
Z. Zong
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Water Entry ◽  
Multiphase Model ◽  
Local Pressure ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Pressure Peak ◽  
Smoothed Particle ◽  
Air Cushion ◽  
Peak Value

In this paper, the hydrodynamic behaviors of a typical convex object during water entry are numerically investigated using a meshfree particle method, smoothed particle hydrodynamics (SPH). In order to consider the practical air-cushion effects during water–entry process, a multiphase model with interface force is incorporated to the SPH method to maintain sharp water–air interface. Three numerical examples including bubble rising, water impact on a flate plate and water entry of a wedge are firstly simulated to validate the effectiveness of the multiphase SPH method in predicting the slamming forces and trajectories of falling objects. Water entry of free falling convex objects with different shapes and sizes is then simulated using the validated numerical method for comparative studies. Two slamming processes, including the convex slamming and the structure slamming, are observed in simulations, with double-jetting pattern occurring after the structure slamming. The air-cushion effects are well captured with slamming-induced vortexes clearly shown in the simulation snapshots. Quantitatively, significant drop in pressure peak value is observed when the dimensionless width of the convex is larger than 0.2. Among various shapes of convexes, the square shaped convex experiences the minimal local pressure peak value.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

Numerical Simulation of Die Swell of Second-Order Fluids Using Smoothed Particle Hydrodynamics

2010 ◽  
Author(s):  
Samir Hassan Sadek ◽  
Mehmet Yildiz
Keyword(s):  
Free Surface ◽  
Smoothed Particle Hydrodynamics ◽  
Second Order ◽  
Rheological Parameters ◽  
Die Swell ◽  
Two Dimensional ◽  
Polymeric Fluid ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Second Order Fluids

This work presents the development of both weakly compressible and incompressible Smoothed Particle Hydrodynamics (SPH) models for simulating two-dimensional transient viscoelastic free surface flow which has extensive applications in polymer processing industries. As an illustration with industrial significance, we have chosen to model the extrudate swell of a second-order polymeric fluid. The extrudate or die swell is a phenomenon that takes place during the extrusion of polymeric fluids. When a polymeric fluid is forced through a die to give a polymer its desired shape, due to its viscoelastic non-Newtonian nature, it shows a tendency to swell or contract at the die exit depending on its rheological parameters. The die swell phenomenon is a typical example of a free surface problem where the free surface is formed at the die exit after the polymeric fluid has been extruded. The swelling process leads to an undesired increase in the dimensions of the extrudate. To be able to obtain a near-net shape product, the flow in the extrusion process should be well-understood to shed some light on the important process parameters behind the swelling phenomenon. To this end, a systematic study has been carried out to compare constitutive models proposed in literature for second-order fluids in terms of their ability to capture the physics behind the swelling phenomenon. The effect of various process and rheological parameters on the die swell such as the extrusion velocity, normal stress coefficients, and Reynolds and Deborah numbers have also been investigated. The models developed here can predict both swelling and contraction of the extrudate successfully. The die swell problem was solved for a wide range of Deborah numbers and for two different Re numbers. The numerical model was validated through the solution of fully developed Newtonian and Non-Newtonian viscoelastic flows in a two-dimensional channel, and the results of these two benchmark problems were compared with analytic solutions, and good agreements were obtained.

scholarly journals Progress in the Smoothed Particle Hydrodynamics Method to Simulate and Post-process Numerical Simulations of Annular Airblast Atomizers

2020 ◽  
Vol 105 (4) ◽  
pp. 1119-1147
Author(s):  
G. Chaussonnet ◽  
T. Dauch ◽  
M. Keller ◽  
M. Okraschevski ◽  
C. Ates ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Flux Ratio ◽  
Liquid Sheet ◽  
Sph Method ◽  
Post Process ◽  
Finite Time Lyapunov Exponent ◽  
Fragmentation Spectrum ◽  
Particle Hydrodynamics ◽  
Primary Breakup ◽  
Smoothed Particle

AbstractThis paper illustrates recent progresses in the development of the smoothed particle hydrodynamics (SPH) method to simulate and post-process liquid spray generation. The simulation of a generic annular airblast atomizer is presented, in which a liquid sheet is fragmented by two concentric counter swirling air streams. The accent is put on how the SPH method can bridge the gap between the CAD geometry of a nozzle and its characterization, in terms of spray characteristics and dynamics. In addition, the Lagrangian nature of the SPH method allows to extract additional data to give further insight in the spraying process. First, the sequential breakup events can be tracked from one large liquid blob to very fine stable droplets. This is herein called the tree of fragmentation. From this tree of fragmentation, abstract quantities can be drawn such as the breakup activity and the fragmentation spectrum. Second, the Lagrangian coherent structures in the turbulent flow can be determined easily with the finite-time Lyapunov exponent (FTLE). The extraction of the FTLE is particularly feasible in the SPH framework. Finally, it is pointed out that there is no universal and ultimate non-dimensional number that can characterize airblast primary breakup. Depending on the field of interest, a non-dimensional number (e.g. Weber number) might be more appropriate than another one (e.g. momentum flux ratio) to characterize the regime, and vice versa.

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