Flid-solid multiphase flow simulator using a SPH-DEM coupled method in consideration of liquid bridge force related to water content

Most of the recent natural disasters such as landslide and tsunamis are complex phenomena in which fluid, ground, structures, etc. affect each other. Therefore, it is necessary to study from various mechanical viewpoints. Among them, in this research, we focus on “soilwater mixed phase flow” where fluid and soil affect each other, such as slope failure and ground collapse. In this study, ISPH method is applied for fluid simulation while DEM is applied for modelling of soil behavior. Then, a general-purpose fluid-solid multiphase flow simulator is developed using the ISPH-DEM coupling method. In addition, in DEM analysis, there are problems in consideration of apparent cohesion related to water content. In our analysis method, in order to adapt to unsaturated ground, the liquid bridge force model proposed in the powder technology field

Development of a fluid-solid multiphase flow simulator by a SPH-DEM coupled method for simulating a seawall destruction due to soil foundation scour

In 2011, Tohoku-Kanto earthquake tsunami caused serious damage to the port and coastal structures such as breakwaters and seawalls. The damage mechanism of these structures has been studied in the past, and it is found that there are some causes. In this study, a new simulation tool taking account of the soil scouring and seepage flow phenomena is developed to represent and predict the collapse of the breakwater with SPH-DEM coupled method

Double-Diffusive Natural Convection with Cross-Diffusion Effects in an Anisotropic Porous Enclosure Using ISPH Method

A study on heat and mass transfer behaviour on an anisotropic porous medium embedded in square cavity/annulus is conducted using Incompressibe Smoothed Particle Hydrodynamics (ISPH) method. In the case of square cavity, the left wall has hot temperature Th and mass Ch and the right wall has cool temperature Tc and mass Cc and both of the top and bottom walls are adiabatic. While in the case of square annulus, the inner surface wall is considered to have a cool temperature Tc and mass Cc while the outer surface is exposed to a hot temperature Th and mass Ch. The governing partial differential equations are transformed to non-dimensional governing equations and are solved using ISPH method. The results present the influences of the Dufour and Soret effects on the heat and mass transfer. The effects of various physical parameters such as Darcy parameter, permeability ratio, inclination angle of permeability and Rayleigh numbers on the temperature and concentration profiles together with the local Nusselt and Sherwood numbers are presented graphically. The results from the current ISPH method are well validated and have favorable comparisons with previously published results and solutions by the finite volume method

Verification and validation in highly viscous fluid simulation using a fully implicit sph method

Catastrophes involving mass movements has always been a great threat to civilizations. We propse to simplify the behavior of the mass movement material as a highly viscous fluid, possibly non-Newtonian. In this context, this study describes the application of two improvements in highly viscous fluid simulations using the smoothed particle hydrodynamics (SPH) method: an implicit time integration scheme to overcome the problem of impractically small time-step restriction, and the introduction of air ghost particles to fix problems regarding the free-surface treatment. The application of a fully implicit time integration method implies an adaptation of the wall boundary condition, which is also covered in this study. Furthermore, the proposed wall boundary condition allows for different slip conditions, which is usually difficult to adopt in SPH. To solve a persistent problem on the SPH method of unstable pressure distributions, we adopted the incompressible SPH [1] as a basis for the implementation of these improvements, which guarantees stable and accurate pressure distribution. We conducted non-Newtonian pipe flow simulations to verify the method and a variety of dam break and wave generated by underwater landslide simulations for validation. Finally, we demonstrate the potential of this method with the highly viscous vertical jet flow over a horizontal plate test, which features a complex viscous coiling behavior

Performance of large scaled tsunami run-up analysis using explicit ISPH method

The tsunami run-up simulation by the particle method at city level needs to huge number of particle at least 1 billion particles. The conventional particle simulation method is not easy to solve these huge problem even on the premise of using supercomputer. Then, a new particle method ’fully explicit Incompressible SPH’ is developed that takes into consideration both calculation efficiency and accuracy. Finally, we demonstrate the future plan how to use our simulation resultes for a practical ’Soft’ disaster mitigation method through the evacuation education with the Virtual Reality(VR) system

Bridges wash out simulation during tsunami by a stabilized ISPH method

In 2011, the huge tsunami caused by the great east Japan earthquake devastated many infrastructures in pacific coast of north eastern Japan. Particularly, collapse of bridges caused a traffic disorder and these collapse behaviors led to delay of recovery after the disaster. In this study, the bridge wash away accident is selected as a target issue, and it is represented in order to investigate the criteria and its mechanism by a numerical simulation. For this purpose, Incompressible Smoothed Particle Hydrodynamics (ISPH) Method, which is one of the pure mesh free methods, is utilized for the rigid body motion simulation. In this study, rigid body motion is introduced for the fluid-rigid interaction behavior during bridge wash away simulation. In the numerical analysis, the upper bridge structure is washed out by receiving an impact fluid force. The validation tests in two scales showed good agreement with experimental test and the real accident on the great east Japan earthquake tsunami

A Stabilized Incompressible SPH Method by Relaxing the Density Invariance Condition

A stabilized Incompressible Smoothed Particle Hydrodynamics (ISPH) is proposed to simulate free surface flow problems. In the ISPH, pressure is evaluated by solving pressure Poisson equation using a semi-implicit algorithm based on the projection method. Even if the pressure is evaluated implicitly, the unrealistic pressure fluctuations cannot be eliminated. In order to overcome this problem, there are several improvements. One is small compressibility approach, and the other is introduction of two kinds of pressure Poisson equation related to velocity divergence-free and density invariance conditions, respectively. In this paper, a stabilized formulation, which was originally proposed in the framework of Moving Particle Semi-implicit (MPS) method, is applied to ISPH in order to relax the density invariance condition. This formulation leads to a new pressure Poisson equation with a relaxation coefficient, which can be estimated by a preanalysis calculation. The efficiency of the proposed formulation is tested by a couple of numerical examples of dam-breaking problem, and its effects are discussed by using several resolution models with different particle initial distances. Also, the effect of eddy viscosity is briefly discussed in this paper

The DBCLS BioHackathon: standardization and interoperability for bioinformatics web services and workflows. The DBCLS BioHackathon Consortium*

Web services have become a key technology for bioinformatics, since life science databases are globally decentralized and the exponential increase in the amount of available data demands for efficient systems without the need to transfer entire databases for every step of an analysis. However, various incompatibilities among database resources and analysis services make it difficult to connect and integrate these into interoperable workflows. To resolve this situation, we invited domain specialists from web service providers, client software developers, Open Bio* projects, the BioMoby project and researchers of emerging areas where a standard exchange data format is not well established, for an intensive collaboration entitled the BioHackathon 2008. The meeting was hosted by the Database Center for Life Science (DBCLS) and Computational Biology Research Center (CBRC) and was held in Tokyo from February 11th to 15th, 2008. In this report we highlight the work accomplished and the common issues arisen from this event, including the standardization of data exchange formats and services in the emerging fields of glycoinformatics, biological interaction networks, text mining, and phyloinformatics. In addition, common shared object development based on BioSQL, as well as technical challenges in large data management, asynchronous services, and security are discussed. Consequently, we improved interoperability of web services in several fields, however, further cooperation among major database centers and continued collaborative efforts between service providers and software developers are still necessary for an effective advance in bioinformatics web service technologies

The 3rd DBCLS BioHackathon: improving life science data integration with Semantic Web technologies.

BACKGROUND: BioHackathon 2010 was the third in a series of meetings hosted by the Database Center for Life Sciences (DBCLS) in Tokyo, Japan. The overall goal of the BioHackathon series is to improve the quality and accessibility of life science research data on the Web by bringing together representatives from public databases, analytical tool providers, and cyber-infrastructure researchers to jointly tackle important challenges in the area of in silico biological research. RESULTS: The theme of BioHackathon 2010 was the 'Semantic Web', and all attendees gathered with the shared goal of producing Semantic Web data from their respective resources, and/or consuming or interacting those data using their tools and interfaces. We discussed on topics including guidelines for designing semantic data and interoperability of resources. We consequently developed tools and clients for analysis and visualization. CONCLUSION: We provide a meeting report from BioHackathon 2010, in which we describe the discussions, decisions, and breakthroughs made as we moved towards compliance with Semantic Web technologies - from source provider, through middleware, to the end-consumer.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are