Implementation of three-dimensional physical reflective boundary conditions in mesh-free particle methods for continuum fluid dynamics: Validation tests and case studies

2019 ◽  
Vol 31 (10) ◽  
pp. 103606 ◽  
Author(s):  
Carlos Alberto Dutra Fraga Filho ◽  
Chong Peng ◽  
Md Rushdie Ibne Islam ◽  
Christopher McCabe ◽  
Samiullah Baig ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Boundary Conditions ◽  
Case Studies ◽  
Free Particle ◽  
Three Dimensional ◽  
Particle Methods ◽  
Mesh Free ◽  
Validation Tests

scholarly journals Boundary conditions of patient-specific fluid dynamics modelling of cavopulmonary connections: possible adaptation of pulmonary resistances results in a critical issue for a virtual surgical planning

2011 ◽  
Vol 1 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Giancarlo Pennati ◽  
Chiara Corsini ◽  
Daria Cosentino ◽  
Tain-Yen Hsia ◽  
Vincenzo S. Luisi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Critical Issue ◽  
Patient Specific ◽  
Imaging Data ◽  
Venae Cavae ◽  
Cavopulmonary Anastomosis ◽  
Operative Planning ◽  
The Right

Cavopulmonary connections are surgical procedures used to treat a variety of complex congenital cardiac defects. Virtual pre-operative planning based on in silico patient-specific modelling might become a powerful tool in the surgical decision-making process. For this purpose, three-dimensional models can be easily developed from medical imaging data to investigate individual haemodynamics. However, the definition of patient-specific boundary conditions is still a crucial issue. The present study describes an approach to evaluate the vascular impedance of the right and left lungs on the basis of pre-operative clinical data and numerical simulations. Computational fluid dynamics techniques are applied to a patient with a bidirectional cavopulmonary anastomosis, who later underwent a total cavopulmonary connection (TCPC). Multi-scale models describing the surgical region and the lungs are adopted, while the flow rates measured in the venae cavae are used at the model inlets. Pre-operative and post-operative conditions are investigated; namely, TCPC haemodynamics, which are predicted using patient-specific pre-operative boundary conditions, indicates that the pre-operative balanced lung resistances are not compatible with the TCPC measured flows, suggesting that the pulmonary vascular impedances changed individually after the surgery. These modifications might be the consequence of adaptation to the altered pulmonary blood flows.

scholarly journals Recent Progress on Mesh-free Particle Methods for Simulations of Multi-phase Flows: A Review

2020 ◽  
Vol 37 (0) ◽  
pp. 132-144 ◽  
Author(s):  
Mikio Sakai ◽  
Yuki Mori ◽  
Xiaosong Sun ◽  
Kazuya Takabatake
Keyword(s):  
Recent Progress ◽  
Free Particle ◽  
Particle Methods ◽  
Mesh Free ◽  
Multi Phase

scholarly journals Multiphase mesh-free particle modeling of local sediment scouring with μ(I) rheology

2018 ◽  
Vol 21 (2) ◽  
pp. 279-294 ◽  
Author(s):  
Ehsan Jafari Nodoushan ◽  
Ahmad Shakibaeinia
Keyword(s):  
Free Particle ◽  
Particle Methods ◽  
Viscoplastic Fluid ◽  
Particle Model ◽  
Numerical Techniques ◽  
Low Viscosity ◽  
Particle Modeling ◽  
Mesh Free ◽  
Weakly Compressible ◽  
Moving Particle

Abstract Sediment scouring is a common example of highly dynamic sediment transport. Considering its complexities, the accurate prediction of such a highly dynamic multiphase granular flow system is a challenge for the traditional numerical techniques that rely on a mesh system. The mesh-free particle methods are a newer generation of numerical techniques with an inherent ability to deal with the deformations and fragmentations of a multiphase continuum. This study aims at developing and evaluating a multiphase mesh-free particle model based on the weakly compressible moving particle semi-implicit (WC-MPS) formulation for simulation of sediment scouring. The sediment material is considered as a non-Newtonian viscoplastic fluid, whose behavior is predicted using a regularized μ(I) rheological model in combination with pressure-dependent yield criteria. The model is first validated for a benchmark problem of viscoplastic Poiseuille flow. It is then applied and evaluated for the study of two classical sediment scouring cases. The results show that the high-velocity flow currents and the circulations can create a low-viscosity region on the surface of the sediment continuum. Comparing the numerical results with the experimental measurements shows a good accuracy in prediction of the sediment profile, especially the shape and dimensions of the scour hole.

Numerical Simulation of Behavior of Sand Particles during High-Speed Penetration with Particle Method

2016 ◽  
Vol 715 ◽  
pp. 198-202
Author(s):  
Ryota Shimono ◽  
Keiko Watanabe
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Free Particle ◽  
Particle Method ◽  
Particle Methods ◽  
Sand Particle ◽  
Mesh Free ◽  
Research Themes ◽  
Macro Scale ◽  
Sand Particles

The phenomena that occur during high-speed penetration of a projectile into sand particles are interesting subjects in engineering. The macro-scale research themes are the behavior of the ejected sand particles and the progress of the high-speed projectile, while the micro-scale research themes are the deformation and fragmentation of a single sand particle. Studies of these unique phenomena were conducted using both experiments and numerical simulation. Although accurate simulation of the behavior of sand particles during high-speed penetration is difficult because sand particles have characteristics of both fluids and solids, the reproducibility of the actual phenomena has improved in recent years with the development of particle methods. In our research, we conducted simulations of the phenomena using Smoothed Particle Hydrodynamics (SPH), which is a mesh-free, particle-based method. The results showed the possibility of accurate reproduction during high-speed projectile penetration into sand particles at the macro-scale.

Three-Dimensional Thermo-Elasto-Hydrodynamic Computational Fluid Dynamics Model of a Tilting Pad Journal Bearing—Part I: Static Response

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Jongin Yang ◽  
Alan Palazzolo
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Journal Bearing ◽  
Three Dimensional ◽  
Cfd Model ◽  
Flow And Heat Transfer ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing

This paper presents the first simulation model of a tilting pad journal bearing (TPJB) using three-dimensional (3D) computational fluid dynamics (CFD), including multiphase flow, thermal-fluid, transitional turbulence, and thermal deformation of the shaft and pads employing two-way fluid–structure interaction (FSI). Part I presents a modeling method for the static performance. The model includes flow between pads BP, which eliminates the use of an uncertain, mixing coefficient (MC) in Reynold's equation approaches. The CFD model is benchmarked with Reynold's model with a 3D thermal-film, when the CFD model boundary conditions are consistent with the Reynolds boundary conditions. The Reynolds model employs an oversimplified MC representation of the three-dimensional mixing effect of the BP flow and heat transfer, and it also employs simplifying assumptions for the flow and heat transfer within the thin film between the journal and bearing. This manufactured comparison shows good agreement between the CFD and Reynold's equation models. The CFD model is generalized by removing these fictitious boundary conditions on pad inlets and outlets and instead models the flow and temperature between pads. The results show that Reynold's model MC approach can lead to significant differences with the CFD model including detailed flow and thermal modeling between pads. Thus, the CFD approach provides increased reliability of predictions. The paper provides an instructive methodology including detailed steps for properly applying CFD to tilt pad bearing modeling. Parts I and II focus on predicting static and dynamic response characteristic responses, respectively.

Various issues relating to computational fluid dynamics simulations of carotid bifurcation flow based on models reconstructed from three-dimensional ultrasound images

2003 ◽  
Vol 217 (5) ◽  
pp. 393-403 ◽  
Author(s):  
A D Augst ◽  
D C Barratt ◽  
A D Hughes ◽  
S A McG Thom ◽  
X Y Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Internal Carotid ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
External Carotid ◽  
Flow Data ◽  
Cfd Simulations ◽  
The Common

Computational fluid dynamics (CFD) flow simulation techniques have the potential to enhance understanding of how haemodynamic factors are involved in atherosclerosis. Recently, three-dimensional ultrasound has emerged as an alternative to other three-dimensional imaging techniques, such as magnetic resonance angiography (MRA). The method can be used to generate accurate vascular geometry suitable for CFD simulations and can be coupled with Doppler ultrasound to provide physiologically realistic flow boundary conditions. However, there are various ways to utilize the flow data acquired, possibly leading to different results regarding both flow and wall shear stress patterns. A disadvantage of three-dimensional ultrasound for imaging the carotid bifurcation has been established as being the scanning limitation of the jawbone position. This may make artificial extensions of the internal and/or external carotid arteries necessary, which in turn may influence the predicted flow patterns. Flow simulations were carried out for three outflow calculation schemes as well as four geometries with different extensions to the carotid daughter vessels. It was found that variation of flow patterns was more strongly influenced by the outflow conditions than by the extensions of the daughter vessels. Consequently, it is recommended that for future CFD simulations of carotid flow using three-dimensional ultrasound data, the outflow boundary conditions should rely on the most accurate measurement available, and flow data recorded in the common and internal carotid are considered more reliable than data from the external carotid. Even though the extended lengths of the daughter vessels have insignificant effects on the predicted haemodynamic parameters, it would be a safer option to extend the internal carotid by approximately three times the diameter of the common carotid artery.

Dynamic analysis of functionally graded piezoelectric cylindrical panels by a three-dimensional mesh-free model

2017 ◽  
Vol 28 (18) ◽  
pp. 2516-2527 ◽  
Author(s):  
Mehrdad Foroutan ◽  
Farah Mohammadi ◽  
Jaber Alihemati ◽  
Arman Soltanimaleki
Keyword(s):  
Boundary Conditions ◽  
Dynamic Analysis ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Power Law Distribution ◽  
Mesh Free ◽  
Free Model ◽  
Cylindrical Panels ◽  
Functionally Graded Piezoelectric

In this work, dynamic analysis of functionally graded piezoelectric cylindrical panels is carried out under different mechanical and electrical loads and boundary conditions by a three-dimensional mesh-free model. Moving least squares approximation is used in the weak form of governing equations including three-dimensional equations of motion and Maxwell’s equation. Transformation method is applied to impose the essential boundary conditions. A power-law distribution is used to determine the effective material properties in the panel. The resulting system of differential equations is solved using Newmark time integration method. After validation of the proposed model, parametric study is carried out to investigate the effects of boundary conditions, geometry of panel, and distribution of constituent materials on natural frequencies and dynamic response of functionally graded piezoelectric panel.

Stable time step estimates for mesh-free particle methods

2012 ◽  
Vol 91 (4) ◽  
pp. 450-456 ◽  
Author(s):  
Grand Roman Joldes ◽  
Adam Wittek ◽  
Karol Miller
Keyword(s):  
Free Particle ◽  
Particle Methods ◽  
Time Step ◽  
Mesh Free

MPS–FEM PARTITIONED COUPLING APPROACH FOR FLUID–STRUCTURE INTERACTION WITH FREE SURFACE FLOW

2014 ◽  
Vol 11 (04) ◽  
pp. 1350101 ◽  
Author(s):  
N. MITSUME ◽  
S. YOSHIMURA ◽  
K. MUROTANI ◽  
T. YAMADA
Keyword(s):  
Free Surface ◽  
Free Particle ◽  
Fluid Structure Interaction ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Particle Methods ◽  
The Finite Element Method ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Mesh Free

Fluid–structure interaction analysis involving free surface flow has been investigated using mesh-based methods or mesh-free particle methods. While mesh-based methods have several problems in dealing with the fragmentation of geometry and moving interfaces and with the instability of nonlinear advective terms, mesh-free particle methods can deal with free surface and moving boundary relatively easily. In structural analyses, the finite element method, which is a mesh-based method, has been investigated extensively and can accurately deal with not only elastic problems but also plastic and fracture problems. Thus, the present study proposes a partitioned coupling strategy for fluid–structure interaction problems involving free surfaces and moving boundaries that calculates the fluid domain using the moving particle simulation method and the structure domain using the finite element method. As the first step, we apply a conventional serial staggered algorithm as a weak coupling scheme. In addition, for the verification of the proposed method, the problem of a breaking dam on an elastic wall is calculated, and the results are compared with the results obtained by other methods.

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