Effects of Wall Condition of a Plunging Body on Splash

2011 ◽  
Author(s):  
Masao Yokoyama ◽  
Yoshihiro Kubota ◽  
Osamu Mochizuki
Keyword(s):  
Numerical Simulation ◽  
Implicit Method ◽  
Water Tank ◽  
Air Cavity ◽  
Slip Ratio ◽  
Mps Method ◽  
Swelling Degree ◽  
Living Things ◽  
Wall Condition ◽  
Moving Particle

Splashes generated by hydrogel sphere were simulated numerically and experimentally for investigating the effects of slip like mucus of living things. Numerical simulation using MPS (Moving Particle Semi-implicit) method was carried out. We defined the slip ratio as the swelling degree of hydrogel and installed the slip ratio into the MPS method. The swelling degree is the ratio of the weight of water against that of hydrogel. We simulated the splashes generated by the hydrogel spheres which had the different swelling degree plunging into water. As the evaluation of swelling degree on the surface of actual hydrogel spheres we also tested by using the hydrogel spheres plunging into water experimentally. The height of splash as a result of reaction of the air cavity became higher according to the increase of the swelling degree. The speed of hydrogel sphere sinking in water tank was also quicker in the numerical simulation. The reason of these results was that the velocity of water around the hydrogel sphere became quicker due to the slip on the surface.

A Fundamental Study on the Applicability of the Floating Large Size Tsunami Shelter

2016 ◽  
Author(s):  
Takuma Kishi ◽  
Kiyokazu Minami ◽  
Mitsuhiro Masuda
Keyword(s):  
Numerical Simulation ◽  
Implicit Method ◽  
Water Tank ◽  
Fundamental Study ◽  
Collision Model ◽  
Large Size ◽  
Tank Experiment ◽  
Water Tank Experiment ◽  
Moving Particle ◽  
Run Up

A floating large-size tsunami shelter (FLTS) has been proposed. The shelter can evacuate more than 1500 people to evacuate from run-up tsunami. The floating tsunami shelter can be lifted by buoyancy when tsunami hitting. In this study, First, Authors assumed Principal specifications of the FLTS from estimation of damage and second we evaluated the validity and safety of a floating large size tsunami shelter using the mooring dolphin by water tank experiment and numerical simulation that is moving particle semi-implicit method (MPS). As a result, enough performance was recognized. The mooring of dolphin was reduced the motion against 10m height tsunami than no moored. However it became clear about the numerical simulation that improvement was more necessary. In particular, the collision model was necessary improved by the existing model.

A Fundamental Study on the Damage of Wash Up to the Quay of the Moored Vessel in Tsunamis Using the MPS Method Considered the Fender Influences

2018 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Simulation Method ◽  
Implicit Method ◽  
Spring Model ◽  
Mooring Lines ◽  
Fundamental Study ◽  
Protection Measures ◽  
Mps Method ◽  
Moving Particle

In the case of vessels are moored at the quay, the drift and the wash up to the quay due to the broke of mooring lines is occurred by the tsunamis. In the previous study, the authors are examined to the applicability of the proposed tsunami protection measures as the install more mooring lines (IMML) and the floating tsunami protection wharf (FTPW). However, the Fender influences were not considered in previous authors studies. In this study, the fender influences are considered on the numerical simulation. The three-dimensional MPS (Moving Particle Semi-implicit) method is used as numerical simulation method. The linear compressing spring model is used as the fender model. The fender influences were investigated against the influences of tsunami protection measures using IMML and the damage status of vessel.

scholarly journals NUMERICAL SIMULATION OF TSUNAMI CURRENTS

2011 ◽  
Vol 1 (32) ◽  
pp. 6 ◽  
Author(s):  
Eizo Nakaza ◽  
Tsunakiyo Iribe ◽  
Muhammad Abdur Rouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Open Channel ◽  
Implicit Method ◽  
Simulation Results ◽  
Moving Particle ◽  
Fixed Structure ◽  
Tsunami Currents

The paper aims to simulate Tsunami currents around moving and fixed structures using the moving-particle semi-implicit method. An open channel with four different sets of structures is employed in the numerical model. The simulation results for the case with one structure indicate that the flow around the moving structure is faster than that around the fixed structure. The flow becomes more complex for cases with additional structures.

Simulation of the Mooring Vessels in Tsunamis Using the MPS Method Considers Leading Wave and Backwash

2012 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda ◽  
Tomoki Ikoma
Keyword(s):  
Experimental Results ◽  
Implicit Method ◽  
Present Calculation ◽  
Mps Method ◽  
Calculation Results ◽  
Moving Particle

The present paper describes the simulation of behavior of mooring vessels in tsunami using the 3-D MPS (Moving Particle Semi-implicit) Method for considering leading wave and backwash effect. The chain of a disaster is brought about by two kinds of tsunami. The chain of disaster means breaking the mooring tether, grounding on a wharf, drift to continental areas, the collision with building by leading wave and the outflow of the floating matter by backwash. In this research, the 3D-MPS method is applied, and the bore like wave is applied as an assumed tsunami. The expression of backwash is tried by water pillar collapse. The present calculation results are compared with the experimental results and the applicability of the MPS method is discussed. In addition, the vehicle is arranged on a wharf, and the chain of disaster is simulated.

Simulation of Red Blood Cell Passing Through Constrictions Using Modified Moving Particle Semi-Implicit Method

2011 ◽  
Author(s):  
K. Firoozbakhsh ◽  
M. T. Ahmadian ◽  
M. Hasanian
Keyword(s):  
Mechanical Behavior ◽  
Experimental Studies ◽  
Small Time ◽  
Implicit Method ◽  
Parallel Plates ◽  
Time Step ◽  
Mps Method ◽  
Time Step Size ◽  
Small Time Step ◽  
Moving Particle

During the circulation of RBC it undergoes elastic deformation as it passes through micro-capillaries where the inner diameter of the constriction can be about 3 micro meters. It means RBC shape must be changed in order to pass through these narrow channels. The role of mechanical behavior of RBC and the deformability traits of RBC are observed with the several experimental studies [1]. Several methods were implemented to simulate the mechanical behavior of RBCs in micro-capillaries [1, 2]. One of the most recent methods is Moving Particle Semi-implicit method (MPS) which is a Lagrangian method with semi-implicit algorithm that guaranties the incompressibility of the fluid. MPS method was implemented for simulation of RBC motion through parallel plates by Tsubota et al. 2006 [3]. Due to small Reynolds number and the Diffusion number restrictions, implementation of small time step size would be necessary which leads to long time simulation. By the way in case of complex geometries or FSI problems, standard MPS method has a delicate pressure solver which leads to diverge the solution. So in these cases using a small time step can help to overcome the problem. Some studies have applied a new approach for time integration and the fractional time step method is employed to overcome the noticed problem. Yohsuke Imai and coworkers (2010) have developed the former studies with two main new approaches [4]. Firstly, evaluation of viscosity is upgraded and secondly boundary condition is assumed to be periodic. Although the developments are really impressive and MPS method has turned into a practical method for simulation of RBC motion in micro-capillaries, but still there are some considerations about using large time steps and error of the velocity profile consequently.

Numerical Simulation of Solitary Wave Using the Fully Lagrangian Method of Moving Particle Semi Implicit

2014 ◽  
Author(s):  
Mohammad Amin Nabian ◽  
Leila Farhadi
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Solitary Wave ◽  
Stokes Equations ◽  
Rock Avalanche ◽  
Water Tank ◽  
Step Method ◽  
Fractional Step Method ◽  
Time Step ◽  
Moving Particle

A mesh-less numerical approach, called the moving particle semi implicit method (MPS), is presented to solve inviscid Navier-Stokes equations in a fully Lagrangian form using a fractional step method. This method consists of splitting each time step in two steps. The fluid is represented with particles and the motion of each particle is calculated through interactions with neighboring particles by means of a kernel function. In this paper, the MPS method is used to simulate a dynamic system consisting of a heavy box sinking vertically into a water tank, known as Scott Russell’s wave generator problem. This problem is an example of a falling rock avalanche into natural or artificial reservoirs. The box sinks into water tank and as a result the water is heaved up to form a solitary wave and a reverse plunging wave which forms a vortex. This vortex follows the solitary wave down the water tank. The good agreement between the numerical simulation and the analytical solution confirms the accuracy of the model. This proves the applicability of the present model in simulating complex free surface problems. The number of particles on free surface is presented as an indicator of stability of the model.

Stable Moving Particle Semi Implicit Method for Modeling Waves Generated by Submarine Landslides

2014 ◽  
Author(s):  
Mohammad Amin Nabian ◽  
Leila Farhadi
Keyword(s):  
Water Surface ◽  
Surface Profile ◽  
Particle Methods ◽  
Water Tank ◽  
Submarine Landslides ◽  
Fractional Step Method ◽  
Time Step ◽  
Mps Method ◽  
Water Surface Profile ◽  
Moving Particle

A mesh-free numerical formulation, known as Moving Particle Semi Implicit (MPS) Method, is used for modeling waves generated by submarine landslides. In this formulation, approximations are provided to the strong form of PDEs on the basis of integral interpolants. The governing equations, Navier-Stokes equations, are solved in a 2D fully Lagrangian form. This method utilizes a fractional step method and splits each time step in two steps. The fluid is represented with particles and the motion of each particle is calculated through interactions with neighboring particles by means of a kernel function. Landslides in this paper are simulated by a submerged triangle rigid wedge sliding along an inclined plane into a water tank. As the wedge sinks, a wave and a vortex is formed. The water surface profile, velocity field and pressure field are represented at different times. To confirm the accuracy of the model, the water surface profile is compared with the experimental data, showing good agreement. Simulations can continue for a long period of time without any instability occurrence and this is a remarkable competency amongst other particle methods. A discussion on multi-size particle strategy and its ability to increase the efficiency of MPS method is provided at the end of the paper.

Numerical simulation of droplet sliding on an inclined surface using moving particle semi-implicit method

2018 ◽  
Vol 5 (4) ◽  
pp. 477-491
Author(s):  
Tsuyoshi Hattori ◽  
Masaharu Sakai ◽  
Shigeru Akaike ◽  
Seiichi Koshizuka
Keyword(s):  
Numerical Simulation ◽  
Implicit Method ◽  
Moving Particle ◽  
Inclined Surface
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