Special Issue "Discrete Multiphysics: Modelling Complex Systems with Particle Methods"

A special issue of ChemEngineering (ISSN 2305-7084).

Deadline for manuscript submissions: closed (30 June 2021) | Viewed by 24907

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Special Issue Editor

Dr. Alessio Alexiadis
E-Mail Website
Guest Editor
School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK
Interests: mathematical modelling; computer simulations; particle methods; molecular dynamics; discrete multiphysics; coupling first-principle modelling with artificial intelligence; deep multiphysics
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Special Issue Information

Dear Colleagues,

I am pleased to invite you to participate in this Special Issue on “Discrete Multiphysics: Modelling Complex Systems with Particle Methods”.

Particle methods have proven their versatility and effectiveness in a variety of applications, ranging from modelling of molecules to the simulation of galaxies. Their power is even amplified when they are coupled together within a discrete multiphysics framework. Moreover, particle methods also couple extremely well (better than mesh-based algorithms) with artificial neural networka, as recent studies on deep multiphysics show.

In this Special Issue, we would very much appreciate contributions that show the power of particle methods in addressing multiphysics problems (including multiphase and complex flows). We specifically target methods such as smoothed particle hydrodynamics (SPH), the lattice spring model (LSM), peridynamics (PD) and the discrete element method (DEM) but other ‘members of the family’ such as Brownian dynamics (BD), dissipative particle dynamics (DPD), and molecular dynamics (MD) are welcome as well.

One of the reasons for looking at particle methods as members of the same family is that they all follow a very similar algorithm. This circumstance carries two consequences: (i) It is straightforward to couple particle methods together, and (ii) it is relatively easy to learn a new particle method if you are already familiar with another one. Therefore, in this Special Issue, emphasis will be given also to (i) contributions that explore the potential of coupling together different particle methods, and (ii) material useful to researchers familiar with a specific particle method who wish to expand their horizons to new ones. Consideration will be also given to contributions that share the ‘tricks of the trade’ of particle methods: i.e., good practice rules that researchers with years of experience have developed and which normally cannot be found in the open literature.

Dr. Alessio Alexiadis
Guest Editor

Manuscript Submission Information

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Keywords

  • particle-based algorithms
  • mesh-free models
  • multiphysics
  • smoothed particle hydrodynamics
  • lattice spring model
  • peridynamics
  • discrete element method
  • complex flows
  • multiphase flows
  • granular flows
  • solid mechanics
  • modelling breakage
  • fluid-structure interactions
  • modelling viscoelastic materials
  • modelling plastic materials

Published Papers (11 papers)

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Research

Article
A 3D Smoothed Particle Hydrodynamics Study of a Non-Symmetrical Rayleigh Collapse for an Empty Cavity
ChemEngineering 2021, 5(3), 63; https://doi.org/10.3390/chemengineering5030063 - 14 Sep 2021
Viewed by 1064
Abstract
In this work the first 3D Smoothed Particle Hydrodynamics model of a Rayleigh collapse for an empty cavity is proposed with the aim of improving the hydrodynamic analysis of a non-symmetrical collapse. The hydrodynamics of the model is validated against the solution of [...] Read more.
In this work the first 3D Smoothed Particle Hydrodynamics model of a Rayleigh collapse for an empty cavity is proposed with the aim of improving the hydrodynamic analysis of a non-symmetrical collapse. The hydrodynamics of the model is validated against the solution of the Rayleigh-Plesset equation for a symmetrical collapse. The model is then used to simulate a non-symmetrical collapse of an empty cavity attached to a solid surface with γ=0.6 induced by an external pressure of 50 [MPa]. The results shows that is possible to identify three regions where the hydrodynamics of the collapsing cavity shows different features. For all the stages of the collapse the simulation shows smooth pressure and velocity fields in the liquid and in the solid phase with the formation of a vortex ring in the final phase of the collapse. Finally, the model is compared to a previous 2D model to highlight strong, weak points and the key differences of both approaches in final phase of the collapse. Full article
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Article
A Simplified Framework for Modelling Viscoelastic Fluids in Discrete Multiphysics
ChemEngineering 2021, 5(3), 61; https://doi.org/10.3390/chemengineering5030061 - 12 Sep 2021
Cited by 2 | Viewed by 1090
Abstract
A simplified modelling technique for modelling viscoelastic fluids is proposed from the perspective of Discrete Multiphysics. This approach, based on the concept of linear additive composition of energy potentials, aims to integrate Smooth Particle Hydrodynamics (SPH) with an equivalent elastic potential tailored for [...] Read more.
A simplified modelling technique for modelling viscoelastic fluids is proposed from the perspective of Discrete Multiphysics. This approach, based on the concept of linear additive composition of energy potentials, aims to integrate Smooth Particle Hydrodynamics (SPH) with an equivalent elastic potential tailored for fluid flow simulations. The model was implemented using a particle-based software, explored and thoroughly validated with results from numerical experiments on three different flow conditions. The model was able to successfully capture a large extent of viscoelastic responses to external forcing, ranging from pure viscous flows to creep-dominated Bingham type of behaviour. It is concluded that, thanks to the modularity and tunable characteristics of the parameters involved, the proposed modelling approach can be a powerful simulation tool for modelling or mimicking the behaviour of viscoelastic substances. Full article
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Article
Fluid-Structure Interaction in Coronary Stents: A Discrete Multiphysics Approach
ChemEngineering 2021, 5(3), 60; https://doi.org/10.3390/chemengineering5030060 - 08 Sep 2021
Cited by 3 | Viewed by 1723
Abstract
Stenting is a common method for treating atherosclerosis. A metal or polymer stent is deployed to open the stenosed artery or vein. After the stent is deployed, the blood flow dynamics influence the mechanics by compressing and expanding the structure. If the stent [...] Read more.
Stenting is a common method for treating atherosclerosis. A metal or polymer stent is deployed to open the stenosed artery or vein. After the stent is deployed, the blood flow dynamics influence the mechanics by compressing and expanding the structure. If the stent does not respond properly to the resulting stress, vascular wall injury or re-stenosis can occur. In this work, a Discrete Multiphysics modelling approach is used to study the mechanical deformation of the coronary stent and its relationship with the blood flow dynamics. The major parameters responsible for deforming the stent are sorted in terms of dimensionless numbers and a relationship between the elastic forces in the stent and pressure forces in the fluid is established. The blood flow and the stiffness of the stent material contribute significantly to the stent deformation and affect its rate of deformation. The stress distribution in the stent is not uniform with the higher stresses occurring at the nodes of the structure. From the relationship (correlation) between the elastic force and the pressure force, depending on the type of material used for the stent, the model can be used to predict whether the stent is at risk of fracture or not after deployment. Full article
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Article
Modelling Particle Agglomeration on through Elastic Valves under Flow
ChemEngineering 2021, 5(3), 40; https://doi.org/10.3390/chemengineering5030040 - 26 Jul 2021
Cited by 2 | Viewed by 1885
Abstract
This work proposes a model of particle agglomeration in elastic valves replicating the geometry and the fluid dynamics of a venous valve. The fluid dynamics is simulated with Smooth Particle Hydrodynamics, the elastic leaflets of the valve with the Lattice Spring Model, while [...] Read more.
This work proposes a model of particle agglomeration in elastic valves replicating the geometry and the fluid dynamics of a venous valve. The fluid dynamics is simulated with Smooth Particle Hydrodynamics, the elastic leaflets of the valve with the Lattice Spring Model, while agglomeration is modelled with a 4-2 Lennard-Jones potential. All the models are combined together within a single Discrete Multiphysics framework. The results show that particle agglomeration occurs near the leaflets, supporting the hypothesis, proposed in previous experimental work, that clot formation in deep venous thrombosis is driven by the fluid dynamics in the valve. Full article
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Article
Numerical Simulations of Red-Blood Cells in Fluid Flow: A Discrete Multiphysics Study
ChemEngineering 2021, 5(3), 33; https://doi.org/10.3390/chemengineering5030033 - 30 Jun 2021
Viewed by 1524
Abstract
In this paper, we present a methodological study of modelling red blood cells (RBCs) in shear-induced flows based on the discrete multiphysics (DMP) approach. The DMP is an alternative approach from traditional multiphysics based on meshless particle-based methods. The proposed technique has been [...] Read more.
In this paper, we present a methodological study of modelling red blood cells (RBCs) in shear-induced flows based on the discrete multiphysics (DMP) approach. The DMP is an alternative approach from traditional multiphysics based on meshless particle-based methods. The proposed technique has been successful in modelling multiphysics and multi-phase problems with large interfacial deformations such as those in biological systems. In this study, we present the proposed method and introduce an accurate geometrical representation of the RBC. The results were validated against available data in the literature. We further illustrate that the proposed method is capable of modelling the rupture of the RBC membrane with minimum computational difficulty. Full article
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Article
How to Modify LAMMPS: From the Prospective of a Particle Method Researcher
ChemEngineering 2021, 5(2), 30; https://doi.org/10.3390/chemengineering5020030 - 13 Jun 2021
Cited by 3 | Viewed by 4373
Abstract
LAMMPS is a powerful simulator originally developed for molecular dynamics that, today, also accounts for other particle-based algorithms such as DEM, SPH, or Peridynamics. The versatility of this software is further enhanced by the fact that it is open-source and modifiable by users. [...] Read more.
LAMMPS is a powerful simulator originally developed for molecular dynamics that, today, also accounts for other particle-based algorithms such as DEM, SPH, or Peridynamics. The versatility of this software is further enhanced by the fact that it is open-source and modifiable by users. This property suits particularly well Discrete Multiphysics and hybrid models that combine multiple particle methods in the same simulation. Modifying LAMMPS can be challenging for researchers with little coding experience. The available material explaining how to modify LAMMPS is either too basic or too advanced for the average researcher. In this work, we provide several examples, with increasing level of complexity, suitable for researchers and practitioners in physics and engineering, who are familiar with coding without been experts. For each feature, step by step instructions for implementing them in LAMMPS are shown to allow researchers to easily follow the procedure and compile a new version of the code. The aim is to fill a gap in the literature with particular reference to the scientific community that uses particle methods for (discrete) multiphysics. Full article
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Article
Fortran Coarray Implementation of Semi-Lagrangian Convected Air Particles within an Atmospheric Model
ChemEngineering 2021, 5(2), 21; https://doi.org/10.3390/chemengineering5020021 - 06 May 2021
Viewed by 1984
Abstract
This work added semi-Lagrangian convected air particles to the Intermediate Complexity Atmospheric Research (ICAR) model. The ICAR model is a simplified atmospheric model using quasi-dynamical downscaling to gain performance over more traditional atmospheric models. The ICAR model uses Fortran coarrays to split the [...] Read more.
This work added semi-Lagrangian convected air particles to the Intermediate Complexity Atmospheric Research (ICAR) model. The ICAR model is a simplified atmospheric model using quasi-dynamical downscaling to gain performance over more traditional atmospheric models. The ICAR model uses Fortran coarrays to split the domain amongst images and handle the halo region communication of the image’s boundary regions. The newly implemented convected air particles use trilinear interpolation to compute initial properties from the Eulerian domain and calculate humidity and buoyancy forces as the model runs. This paper investigated the performance cost and scaling attributes of executing unsaturated and saturated air particles versus the original particle-less model. An in-depth analysis was done on the communication patterns and performance of the semi-Lagrangian air particles, as well as the performance cost of a variety of initial conditions such as wind speed and saturation mixing ratios. This study found that given a linear increase in the number of particles communicated, there is an initial decrease in performance, but that it then levels out, indicating that over the runtime of the model, there is an initial cost of particle communication, but that the computational benefits quickly offset it. The study provided insight into the number of processors required to amortize the additional computational cost of the air particles. Full article
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Article
Mass Spring Models of Amorphous Solids
ChemEngineering 2021, 5(1), 3; https://doi.org/10.3390/chemengineering5010003 - 11 Jan 2021
Cited by 3 | Viewed by 2033
Abstract
In this paper we analyse static properties of mass spring models (MSMs) with the focus of modelling non crystalline materials, and explore basic improvements, which can be made to MSMs with disordered point placement. Presented techniques address the problem of high variance of [...] Read more.
In this paper we analyse static properties of mass spring models (MSMs) with the focus of modelling non crystalline materials, and explore basic improvements, which can be made to MSMs with disordered point placement. Presented techniques address the problem of high variance of MSM properties which occur due to randomised nature of point distribution. The focus is placed on tuning spring parameters in a way which would compensate for local non-uniformity of point and spring density. We demonstrate that a simple force balancing algorithm can improve properties of the MSM on a global scale, while a more detailed stress distribution analysis is needed to achieve local scale improvements. Considered MSMs are three dimensional. Full article
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Article
Modelling Complex Particle–Fluid Flow with a Discrete Element Method Coupled with Lattice Boltzmann Methods (DEM-LBM)
ChemEngineering 2020, 4(4), 55; https://doi.org/10.3390/chemengineering4040055 - 07 Oct 2020
Cited by 5 | Viewed by 3741
Abstract
Particle–fluid flows are ubiquitous in nature and industry. Understanding the dynamic behaviour of these complex flows becomes a rapidly developing interdisciplinary research focus. In this work, a numerical modelling approach for complex particle–fluid flows using the discrete element method coupled with the lattice [...] Read more.
Particle–fluid flows are ubiquitous in nature and industry. Understanding the dynamic behaviour of these complex flows becomes a rapidly developing interdisciplinary research focus. In this work, a numerical modelling approach for complex particle–fluid flows using the discrete element method coupled with the lattice Boltzmann method (DEM-LBM) is presented. The discrete element method and the lattice Boltzmann method, as well as the coupling techniques, are discussed in detail. The DEM-LBM is thoroughly validated for typical benchmark cases: the single-phase Poiseuille flow, the gravitational settling and the drag force on a fixed particle. In order to demonstrate the potential and applicability of DEM-LBM, three case studies are performed, which include the inertial migration of dense particle suspensions, the agglomeration of adhesive particle flows in channel flow and the sedimentation of particles in cavity flow. It is shown that DEM-LBM is a robust numerical approach for analysing complex particle–fluid flows. Full article
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Article
Using Discrete Multiphysics Modelling to Assess the Effect of Calcification on Hemodynamic and Mechanical Deformation of Aortic Valve
ChemEngineering 2020, 4(3), 48; https://doi.org/10.3390/chemengineering4030048 - 03 Aug 2020
Cited by 10 | Viewed by 2500
Abstract
This study proposes a 3D particle-based (discrete) multiphysics approach for modelling calcification in the aortic valve. Different stages of calcification (from mild to severe) were simulated, and their effects on the cardiac output were assessed. The cardiac flow rate decreases with the level [...] Read more.
This study proposes a 3D particle-based (discrete) multiphysics approach for modelling calcification in the aortic valve. Different stages of calcification (from mild to severe) were simulated, and their effects on the cardiac output were assessed. The cardiac flow rate decreases with the level of calcification. In particular, there is a critical level of calcification below which the flow rate decreases dramatically. Mechanical stress on the membrane is also calculated. The results show that, as calcification progresses, spots of high mechanical stress appear. Firstly, they concentrate in the regions connecting two leaflets; when severe calcification is reached, then they extend to the area at the basis of the valve. Full article
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Article
A Coarse Grained Model for Viscoelastic Solids in Discrete Multiphysics Simulations
ChemEngineering 2020, 4(2), 30; https://doi.org/10.3390/chemengineering4020030 - 01 May 2020
Cited by 7 | Viewed by 1918
Abstract
Viscoelastic bonds intended for Discrete Multiphysics (DMP) models are developed to allow the study of viscoelastic particles with arbitrary shape and mechanical inhomogeneity that are relevant to the pharmaceutical sector and that have not been addressed by the Discrete Element Method (DEM). The [...] Read more.
Viscoelastic bonds intended for Discrete Multiphysics (DMP) models are developed to allow the study of viscoelastic particles with arbitrary shape and mechanical inhomogeneity that are relevant to the pharmaceutical sector and that have not been addressed by the Discrete Element Method (DEM). The model is applied to encapsulate particles with a soft outer shell due, for example, to the partial ingress of moisture. This was validated by the simulation of spherical homogeneous linear elastic and viscoelastic particles. The method is based on forming a particle from an assembly of beads connected by springs or springs and dashpots that allow the sub-surface stress fields to be computed, and hence an accurate description of the gross deformation. It is computationally more expensive than DEM, but could be used to define more effective interaction laws. Full article
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