Grain scale simulation of flow in a sandstone sample by using the moving particle semi-implicit (MPS) method

Since the grain scale modelling of flow in porous media is of great interest for the oil industry, the aim of the present research is to show an application of Moving Particle Semi-Implicit (MPS) method to the grain scale simulation of fluid flow in porous media. Geometry data obtained by a high-resolution CT scan of a reservoir sandstone sample was used as input for the simulations. The results of the simulations performed considering different resolutions are given, as well as the head loss and permeability obtained numerically

A NUMERICAL TREATMENT OF THE BOUNDARY CONDITIONS FOR STABLE ASSESSMENT OF HYDRODYNAMIC IMPACT PRESSURE

ABSTRACT One of the critical points in the numerical assessment of hydrodynamic impact loads is accurate and stable descriptions of the pressures. Due to discrete approximations adopted by available numerical methods, unnatural violently-oscillating time histories of the impulsive pressure, caused by unstable or even non-converging numerical computation, are generally obtained. The aim of this paper is to investigate the unstable nature of the impulsive pressure computation. Also, a new numerical treatment of the boundary condition for accurate and stable assessment of the sloshing impact pressure based on rectangular grid system is proposed. The comparisons of the computed results with the experimental ones confirmed the accuracy of the proposed technique. The improvements achieved over the existing approaches are also shown herein. INTRODUCTION Hydrodynamic impact loads due to slamming on ships navigating in rough seas, wave slapping on offshore structures and sloshing inside liquid cargo tanks are of great concern in the design of ships and offshore structures. Motivated by the development of LNG carriers, VLCCs, moored FPSO systems and increasing size of the liquid cargo tanks associated with the concerns on safety issues, many numerical simulation methods have been proposed in the last decades to predict the hydrodynamic loads caused by severe liquid sloshing. However, accurate and stable assessment of the hydrodynamic impact loads is still one of the most critical points of the numerical approaches [1]. Due to the discrete approximation adopted in almost all the methods, in the discrete space that contains the intersection between the free and rigid boundaries, sudden change of the boundary condition from free surface to rigid one generally occurs. As a result, instead of smoothly-decaying hydrodynamic impact pressure in the real situation, unnatura

A comparison between weakly-compressible smoothed particle hydrodynamics (WCSPH) and moving particle semi-implicit (MPS) methods for 3d dam-break flows

Lagrangian particle-based methods have opened new perspectives for the investigation of complex problems with large free-surface deformation. Some well-known particle-based methods adopted to solve non-linear hydrodynamics problems are the smoothed particle hydrodynamics (SPH) and the moving particle semi-implicit (MPS). Both methods modeled the continuum by a system of Lagrangian particles (points) but adopting distinct approaches for the numerical operators, pressure calculation, and boundary conditions. Despite the ability of the particle-based methods in modeling highly nonlinear hydrodynamics, some shortcomings, such as unstable pressure computation and high computational cost remains. In order to assess the performance of these two methods, the weaklycompressible SPH (WCSPH) parallel solver, DualSPHysics, and an in-house incompressible MPS solver are adopted in this work. Two test cases consisting of threedimensional (3D) dam-break problems are simulated, and wave heights, pressures and forces are compared with available experimental data. The influence of the artificial viscosity on the accuracy of WCSPH is investigated. Computational times of both solvers are also compared. Finally, the relative benefits of the methods for solving free-surface problems are discussed, therefore providing directions of their applicability.Comment: 26 pages, 12 figure

Numerical study on performance of perforated breakwater for green water

In this work, the influence of the geometry of lightweight perforated breakwaters on their performance against green water impact loads is investigated systematically through a series of numerical simulations. For this purpose, a fully Lagrangian meshfree particle-based method is adopted to model transient and impulsive hydrodynamic phenomenon with free surface and complex geometry. The green water flow is represented by a dam-break problem; the breakwater is modeled as a perforated plate and the protected installation as a vertical wall. Computed impact force, moment, and impulse on the breakwater and protected wall show nonlinear effects, and the main geometric parameter is the open-area ratio. In addition, the increase in the breakwater height is effective only for low open-area ratios. The influence of the arrangement of the holes are also investigated. Different flow patterns are obtained for small and large gaps between the breakwater and the wall. The relation between the loads on the breakwater and the wall also provides the basis for the optimal design of the breakwater, considering the tolerant hydrodynamic loads of protected structures.Comment: 37 pages, 27 figure

Moving particle simulation with solid-solid contact

Problems of fluid-structure interaction with free surface flow and multi-body interactions are highly nonlinear and complex phenomena, which is challenging for computational modeling and simulation. In the presence of contact or collision between solids, numerical modeling to detect collision and prevent penetration between bodies is required. The objective of this work is to study a numerical model for solid-solid contact and/or collision, based on contact mechanics theories, to reproduce the macroscopic properties of the multi-body interactions in Moving Particle Simulation (MPS) method. MPS is a fully Lagrangian meshfree particle-based approach that is suitable for the modeling complex geometries with large displacements and deformation, including free surface flow with fragmentation and merging and interaction of fluid with multi-bodies. Analytical results are used to perform the calibration of the numerical friction coefficient. The model is applied to a case of free solid transport in free surface flow, modeled as a 3D experimental dam breaking event, in which free solids interact each other and fixed walls. The numerical results from MPS are compared with numerical and experimental results

A coupled analysis of sloshing in floating structures by integrating moving particle semi-implicit (MPS) method with a time domain multibody dynamic analysis software

Sloshing effects inside partially filled tanks on LNG carriers and FPSOs motions cannot be ignored. It is necessary to analyze the floating structures motion with the sloshing behavior simultaneously to obtain more accurate stability predictions because the phenomenon may affect the safety and the operability of the vessels in seaways and during loading and offloading process. In the present study, in order to model the coupled effects of platforms motion in waves and the liquid sloshing inside its tank, a hybrid timedomain simulation approach based on the integration of two simulators is proposed. The Numerical Offshore Tank (TPN) simulator, which is a time domain multibody dynamic analysis software, is used for the simulation of open domain hydrodynamic forces. It is able to perform calculations of coupled floating structures motion with the dynamic of mooring and connection lines and risers considering environmental condition such as wave, current and wind. In the other hand, due to the highly nonlinear aspect of the sloshing phenomenon, the Moving Particle Semi-implicit (MPS) method, which demands huge computing resources and it is more suitable to confined domain problems, is used to simulate the sloshing motion and to calculate the loads on the tank walls. The effects due to sloshing is then feed-backed to the TPN simulator as additional force and moment to solve the motion equation of the floating structure. The calculation can be distributed in a PCs cluster and each sloshing tank is solved in a different node. In this way, it allows the calculation of many tanks without increasing the computational time. Simulations were carried out with and without considering the coupled sloshing motions, and the results were compared to assess the effects of the liquid cargo sloshing on the motion of the floating structure

Numerical simulation of oil leakage, water flooding and damaged stability of oil carrier based on moving particle semi-implicit (MPS) method

Oil leakage or water flooding in a damaged oil carrier are complex phenomena that involve fluid-solid interaction with complicated geometry and multiphase flow. In order to assess the damaged stability and environmental impact when the damage occurs, the present research models the non-linear hydrodynamic problems by using a numerical approach based on MPS (Moving particle Semi-Implicit) method. The comparison of numerical results with that obtained by quasi-static approach shows the limit of validity of the last one. Cconsidering the reduced dimension of the opening of the damage, the effects of the resolution of spatial discretization are also analysed

Flow conditioning modeling and application to particle method

This work comprises the development of a re-circulation boundary condition to simulate the flow around a cylinder using the Moving Particles Simulation (MPS). The recirculation boundary condition consists in the re-injection of the fluid particles that flows out the downstream boundary of the computational domain into the upstream boundary through the application of a periodic boundary condition, and a flow conditioner that comprises a region where the velocities of the fluid particles are gradually adjusted to a uniform flow by suppressing the velocity perturbations. The proposed recirculation boundary condition is applied to simulate the flow around a fixed cylinder and the vortex sheet formation process. The Strouhal Number x Reynolds Number diagram obtained using the MPS method show results close to those present in literature. For the laminar flow, the streamlines of MPS simulations show similarity with experimental results present in literature

Dibujo para ingenieros: ¿que enseñar?

El marco conceptual que abarca el objetivo de este trabajo viene siendo discutida por los autores en varias publicaciones, por causa de la amplitud y desdoblamientos necesarios para el tema. La investigación realizada llevó al establecimiento de un programa para las asignaturas de dibujo de los Cursos de Ingeniería, objetivando una formación técnica y ciudadana, en función de la carga horaria establecida por las universidades brasileñas

Desenho para engenheiros: O que ensinar?

Um novo tipo de educação, voltado para diferentes modos de comunicação. Tal paradigma vem levando à evolução do pensamento transdisciplinar, cujo objetivo é a compreensão do mundo presente e para a qual é imperativa a unidade do conhecimento. Torna imprescindível, deste modo, uma profunda reflexão acerca dos rumos a serem tomados no processo educativo