Simulating fluid-solid interaction problems using an immersed boundary-SPH method

In this work, the Immersed Boundary Method (IBM) is adapted and implemented in the context of Smoothed Particle Hydrodynamics (SPH) method to study moving solid bodies in an incompressible fluid flow. The proposed computational algorithm is verified by solving a number of benchmark particulate flow problems. The results are also compared with those obtained using the same SPH scheme along with a direct solid boundary imposition technique

Physics-Based Damage Predictions for Simulating Testing and Evaluation (T and E) Experiments

This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This report addresses the need to develop computational techniques and physics-based material models for simulating damage to weapons systems resulting from ballistic threats. Modern weapons systems, such as fighter aircraft, are becoming more dependent upon composite materials to reduce weight, to increase strength and stiffness, and to resist adverse conditions resulting from high temperatures and corrosion. Unfortunately, damaged components can have severe and detrimental effects, as evidenced by statistics from Desert Storm indicating that 75% of aircraft losses were attributable to fuel system vulnerability with hydrodynamic ram being the primary kill mechanism. Therefore, this project addresses damage predictions for composite systems that are subjected to ballistic threats involving hydrodynamic ram. A computational technique for simulating fluid-solid interaction phenomena and physics-based material models have been developed for this purpose

A Vortex Method for Bi-phasic Fluids Interacting with Rigid Bodies

We present an accurate Lagrangian method based on vortex particles, level-sets, and immersed boundary methods, for animating the interplay between two fluids and rigid solids. We show that a vortex method is a good choice for simulating bi-phase flow, such as liquid and gas, with a good level of realism. Vortex particles are localized at the interfaces between the two fluids and within the regions of high turbulence. We gain local precision and efficiency from the stable advection permitted by the vorticity formulation. Moreover, our numerical method straightforwardly solves the two-way coupling problem between the fluids and animated rigid solids. This new approach is validated through numerical comparisons with reference experiments from the computational fluid community. We also show that the visually appealing results obtained in the CG community can be reproduced with increased efficiency and an easier implementation

Laptop cooling numerical simulation using Computational Fluid Dynamics

Laptop’s cooling solution is very important. In some cases, due to poor cooling an over heat on the mother board, main chip, and other components occurs, so that the laptop is quickly broken. Therefore it is necessary to know the temperature distribution so that over heat can be overcome. One of the methods to determine the temperature distribution in this final project is a flow simulation, using CFD (Computational Fluid Dynamics), 3D method with the variation if different air flow velocity, i.e. 5 m/s, 10 m/s, and 15 m/s. The higher the air flow rate, the higher the cooling occurs. From the temperature contours it is shown that the hot temperature is built up on the back of the heat sink. The results of the validation of this study and previous studies obtained an error that occurred was around 4%.Keywords: CFD, variation of air flow velocity, laptop

Real-time physical engine for floating objects with two-way fluid-structure coupling

A method to simulate graphic animations of objects floating in a water surface in real time is presented. The fluid is simulated by means of the Lattice Boltzmann method for the shallow-waters equations, and the movement of the floating objects is calculated with a Newtonian physical engine suitable for the mechanics of rigid bodies. A two-way interaction between the fluid surface and the object structures is achieved by providing inputs to the Newtonian engine representing buoyancy, drag and lift forces calculated from the solution of the Lattice Boltzmann scheme, which in turn is perturbed by displacement forces acting at the objects boundaries. The method is tested in animation scenes of boats and different adrift objects, showing excellent rendering rates in desktop computers.Fil: Lazo, Marcos Gonzalo. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Garcia Bauza, Cristian Dario. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Boroni, Gustavo Adolfo. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Clausse, Alejandro. Comision Nacional de Energia Atomica. Gerencia Quimica. CAC; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentin

Computational Modelling of Fluid-Solid Interaction Problems by Coupling Smoothed Particles Hydrodynamics and the Discrete Element Method

Discrete Element Method (DEM) and Smoothed Particles Hydrodynamics (SPH) are integrated to investigate the macroscopic dynamics of fluid-solid interaction (FSI) problems. This coupled model is originated from two different meshless methods without mesh generation, which can handle fluid-particle-structure interactions with structural deformation/failure. With SPH the fluid phase is represented by a set of SPH particle elements moving in accordance with the Navier-Stokes equations. The solid phase consists of single or multiple solid particle(s) phase and deformable structure(s) phase which are represented by DEM particle elements using a linear contact model and a linear parallel contact model to account for the interaction between particle elements, respectively. To couple the fluid phase and solid particle phase, a local volume fraction and a weighted average algorithm are proposed to reformulate the governing equations and the interaction forces. The structure phase is coupled with the fluid phase by incorporating the structure’s DEM particle elements in SPH algorithm. The interaction forces between the solid particles and the structure phases are computed using the linear contact model in DEM. The proposed model is capable of simulating simultaneously fluid-structure interaction, particleparticle interaction and fluid-particle interaction, with good agreement between complicated hybrid numerical methods and experimental results being achieved. Finally, two engineering problems in injection moulding and 3D printing process are carried out to demonstrate the capability of the integrated particle model for simulating fluid-solid interaction problems with the occurrence of structural failure

A particle-based dissolution model using chemical collision energy

We propose a new energy-based method for real-time dissolution simulation. A unified particle representation is used for both fluid solvent and solid solute. We derive a novel dissolution model from the collision theory in chemical reactions: physical laws govern the local excitation of solid particles based on the relative motion of the fluid and solid. When the local excitation energy exceeds a user specified threshold (activation energy), the particle will be dislodged from the solid. Unlike previous methods, our model ensures that the dissolution result is independent of solute sampling resolution. We also establish a mathematical relationship between the activation energy, the inter-facial surface area, and the total dissolution time - allowing for accurate artistic control over the global dissolution rate while maintaining the physical plausibility of the simulation. We demonstrate applications of our method using a number of practical examples, including antacid pills dissolving in water and hydraulic erosion of non-homogeneous terrains. Our method is straightforward to incorporate with existing particle-based fluid simulations

Influence of Nanoparticles and Magnetic Field on the Laminar Forced Convection in a Duct Containing an Elastic Fin

In the present paper, an investigation of the effect of a magnetic field and nanoparticles suspended in pure water on the forced flow in a duct containing an elastic rectangular fin is performed. The nanofluid, i.e., CuO nanoparticles suspended in water, flow in the duct with an inlet fully developed velocity profile and a cold temperature. The lower boundary of the duct is kept at a hot temperature, while the upper boundary is adiabatic. According to the ALE formulation, numerical simulations of the laminar flow are carried out, by employing the software package Comsol Multiphysics, to solve the governing equation system: mass, momentum, energy, and deformation. The behavior of the Nusselt number, of the temperature and velocity fields as well as of the stress profiles are presented and interpreted. As a result, the addition of CuO nanoparticles to pure water improves the local and global heat transfer rate by up to 21.33% compared to pure water. On the other hand, it causes an additional deformation of the elastic fin as well as the increase of the stress due to the presence of the nanoparticles, leading to an increase of its maximum displacement of 34.58% compared to the case of pure water flow. Moreover, the enhancement of the flexibility of the fin (and thus its deformation) leads to a relative reduction in terms of convective heat transfer rate, especially downstream of the fin

An integrated particle model for fluid–particle–structure interaction problems with free-surface flow and structural failure

Discrete Element Method (DEM) and Smoothed Particles Hydrodynamics (SPH) are integrated to investigate the macroscopic dynamics of fluid-particle-structure interaction (FPSI) problems. With SPH the fluid phase is represented by a set of particle elements moving in accordance with the Navier-Stokes equations. The solid phase consists of physical particle(s) and deformable solid structure(s) which are represented by DEM using a linear contact model and a linear parallel contact model to account for the interaction between particle elements, respectively. To couple the fluid phase and solid particles, a local volume fraction and a weighted average algorithm are proposed to reformulate the governing equations and the interaction forces. The structure is coupled with the fluid phase by incorporating the structure's particle elements in SPH algorithm. The interaction forces between the solid particles and the structure are computed using the linear contact model in DEM. The proposed model is capable of simulating simultaneously fluid-structure interaction (FSI), particle-particle interaction and fluid-particle interaction (FPI), with good agreement between complicated hybrid numerical methods and experimental results being achieved. Finally, a specific test is carried out to demonstrate the capability of the integrated particle model for simulating FPSI problems with the occurrence of structural failure