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The current capabilities of numerical codes, which able to model very complex processes, and the existing powerful computational resources, clearly promote the employment of numerical modeling tools to assist design-related tasks. The Computational Rheology Group, from the Institute for Polymers and Composites (IPC) of the University of Minho (UMinho), has been developing and exploiting modeling codes for more than one decade, with a special focus on polymer processing applications. During the last 6 years, most of the numerical developments of the Computational Rheology Group were based on the OpenFOAM® computational library. This talk aims at providing an overview of the computational rheology-related work done at IPC/UMinho, in close cooperation with industry, and at illustrating the advantages of using the computational library OpenFOAM ® for the development of new codes. The presentation will cover both the work done by the group to support the design of polymer processing tools and the development of new solvers in the OpenFOAM® computational library.

Code verification is an intricate but crucial part of numerical code development. Due to the complexity of the partial differential equations, an analytical solution might not exist. In those situations and aiming at proving that the code is solving appropriately the governing equations, the method of manufactured solutions (MMS) is a powerful tool. In this method, a source term is derived to enforce the solution to a predetermined function. By performing a mesh refinement study, one can verify if the code is correctly solving the desired equations. In this work, a methodology that allows the automation of the MMS within the OpenFOAM© framework is proposed. The developed computational framework comprises a set of tools prepared, in an open-source environment, for the symbolic computation of the associated source term, and to generate the code required for its implementation as well as appropriate boundary conditions and functions to calculate the error norms.

The numerical solution of the incompressible Navier-Stokes equations raises challenging numerical issues on the development of accurate and robust discretisation techniques due to the div-grad duality. Significant advances have been achieved in the context of high-order of convergence methods, but many questions remain unsolved in the quest of practical, accurate, and efficient approaches. In particular, the discretisation of problems with arbitrary curved boundaries has been the subject of intensive research, where the conventional practice consists in employing curved meshes to avoid accuracy deterioration. The present work proposes a novel approach, the reconstruction for off-site data method, which employs polygonal meshes to approximate arbitrary smooth curved boundaries with linear piecewise elements. The Navier-Stokes equations are discretised with a staggered finite volume method, and the numerical fluxes are computed on the polygonal mesh elements. Boundary conditions are taken into account via polynomial reconstructions with specific linear constraints defined for a set of points on the physical boundary. The very-high order of convergence is preserved without relying on the full curve parametrisation, avoiding the limitations of curved mesh approaches, such as sophisticated mesh generation algorithms, cumbersome quadrature rules, and complex non-linear transformations. A comprehensive verification benchmark is provided, with numerical test cases for several fluid flow problems, to demonstrate the capability of the proposed approach to achieve very high-orders of convergence.(c) 2022 Elsevier B.V. All rights reserved., R. Costa and J.M. Nobrega acknowledge the financial support by FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operational Fatores de Competitividade, and the National Funds through FCT-Fundacao para a Ciencia e a Tecnologia, project no. UIDB/05256/2020 and UIDP/05256/2020.S. Clain and G.J. Machado acknowledge the financial support by FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operational Fatores de Competitividade, and the National Funds through FCT - Fundacao para a Ciencia e a Tecnologia, project no. UID/FIS/04650/2019.The authors acknowledge the financial support by FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operacional Fatores de Competitividade, and the National Funds through FCT - Fundacao para a Ciencia e a Tecnologia, project no. POCI-01-0145-FEDER-028118.The authors also acknowledge the infrastructure support by SEARCH-ON2 - Revitalization of HPC infrastructure of UMinho, project no. NORTE-07-0162-FEDER-000086, co-funded by the North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF).

Thermoforming is a thermoplastic processing technique commonly used in the rigid packaging industry. The process comprises a heating stage, which aims at allowing the sheet to acquire the required deformability, a deformation stage, in which the sheets conform to the mould surface, and, finally, a cooling stage, which allows the part to be extracted from the mould without distorting. Since there are several processing variables associated with those stages, optimizing the thermoforming process is a complex task. In this work, a multi-objective optimization evolutionary algorithm is proposed to optimize the plastics thermoforming process. For that purpose, the thickness distribution of the final part was optimized considering that it is manufactured from uniform temperature sheets with different thickness distributions, such as constant and spline and concentric profiles. The aims were to minimize the sheet volume, as it implies less material use; assure a minimum value for the part thickness distribution, to avoid hindering its mechanical behavior; and minimize the thickness heterogeneity, i.e., the difference between the thickness of the part and a reference thickness. The Pareto optimal solutions found by the algorithm correspond to different thickness profiles for the three different sheet shapes. In all cases, an improvement of the different profiles along the successive generations of the evolutionary algorithm was obtained, which are related to the objectives considered. Moreover, the initial sheet thickness distribution was found to clearly influence the optimization process. The results obtained for these three different initial sheet shapes indicate that the proposed methodology is valid, providing solutions with physical meaning and with great potential to be applied in more complex cases.

First published: 04 December 2021, Computational modeling is widely used to support the design of profile extrusion dies. However, despite the viscoelastic nature of the polymer melts, the majority of the computational approaches resort to inelastic models. With the aim of assessing the accuracy of the approach usually employed on the modeling of profile extrusion dies, this work aims at comparing the behavior of profile extrusion dies when interrelated viscoelastic (elastic) and generalized Newtonian (inelastic) constitutive models are used. For this purpose, the polymer melt employed in the study was experimentally characterized, being the data collected used to fit a nonlinear multimode viscoelastic (elastic) Giesekus constitutive model. Subsequently, the fitted model was used to generate the material shear flow curve, which was then used to fit a Bird-Carreau (inelastic) constitutive model. The numerical studies undertaken were focused on the extrusion die of two profiles: a simple one, with a rectangular cross-section, and a complex swimming pool cover profile. The results obtained showed that in realistic case studies, the effect of elasticity might be relevant, even when modeling just the flow in the extrusion die flow channel and, thus, should be considered when designing profile extrusion dies., This work was funded by FEDER funds through the COMPETE 2020 Program and National Funds through FCT—Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020/, UIDP/05256/2020, CPCA/A2/6202/2020, CPCA/A2/6231/2020, NORTE-08-5369-FSE-000034, under program IMPULSE—Polímeros e Compósitos: Drivers da Inovação Tecnológica e da Competitividade Industrial. The authors also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER-000086) and Minho Advanced Computing Center (MACC).

The computational modeling has become an indispensable tool to support the engineering design and control of many industrial processes. In polymer processing applications, the simulation of conjugate heat transfer phenomena is critical as rigorous temperature control is necessary to ensure that the produced parts meet the required specifications. In this article, a high-order accurate finite volume method is proposed to improve the numerical accuracy and the computational efficiency of conjugate heat transfer simulations with application in polymer processing. Anisotropic meshes are investigated to significantly reduce the number of unknowns in convection-dominated problems where the higher temperature variations occur perpendicularly to curved boundaries and interfaces. The reconstruction for off-site data method based on polynomial reconstructions is employed to fulfill the prescribed boundary and interface conditions solely using polygonal meshes to avoid the limitations of curved mesh approaches. A code verification benchmark based on manufactured solutions proves that the proposed method provides a fourth-order of convergence and is computationally more cost-effective than the classical second-order of convergence. Moreover, meshes with higher aspect ratios improve the calculation efficiency but suffer from a small accuracy penalty due to conditioning deterioration. Comparison with the classical finite volume discretization techniques, widely implemented in commercial and open-source software packages, is also provided. The applicability and performance of the proposed method are further supported with a practical case study for the sheet extrusion cooling stage., FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operacional Fatores de Competitividade, and the National Funds through FCT - Fundação para a Ciência e a Tecnologia, project no. POCI-01-0145-FEDER-028118, POCI-01-0145-FEDER-028118; FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operational Fatores de Competitividade, and the National Funds through FCT - Fundação para a Ciência e a Tecnologia, project no. UID/FIS/04650/2019, UID/FIS/04650/2019; FEDER - Fundo Europeu de Desenvolvimento Regional, through COMPETE 2020 - Programa Operational Fatores de Competitividade, and the National Funds through FCT- Fundação para a Ciência e a Tecnologia, project no. UID/05256/2020, UID/05256/2020; Portugal 2020 and FSE - Fundo Social Europeu, through NORTE 2020 - Programa Operacional Regional do Norte, project no. NORTE-08-5369-FSE-000034, under program IMPULSE - Polímeros e Compósitos: Drivers da Inovação Tecnológica e da Competitividade Industrial, NORTE-08-5369-FSE-000034

Several numerical meshless methods have been proposed to try to solve some of the limitations of traditional mesh-based methods. Among those, the finite pointset method, which has been applied in several physical problems, shows a great potential. This work presents an extension of the available numerical approaches based on the finite pointset method to allow dealing with generalized Newtonian fluids, which possess a high viscosity. The developed finite pointset method solver is verified through the comparison of its predictions with analytical solutions, for simple flows, and with results provided by the well-established and validated open-source computational library OpenFOAM, for more complex cases studies. The excellent results obtained on the verification case studies prove the proper implementation of the new finite pointset method solver., Financial support for this work was provided by the Government of the State of Coahuila and the Council of Science and Technology of the State of Coahuila (COECYT) through the project FONCYT COAH-2020-C14-B005. J. Miguel Nóbrega also acknowledges the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UIDB/05256/2020, UIDP/05256/2020. The authors would also like to acknowledge the Minho Advanced Computing Center (MACC) for providing HPC resources that contributed to the research results reported within this paper.

The current capabilities of numerical codes, able to model very complex processes, and the existing powerful computational resources, clearly promote the advantages of employing numerical modelling tools to assist any design related tasks. For more than a decade, the Computational Rheology Group, from the Institute for Polymers and Composites / University of Minho (IPC/UMinho), has been developing and exploiting modelling codes to aid the design of different tools, with a special focus on polymer processing applications. During the last 5 years, most of the numerical developments done at IPC/UMinho are based on the OpenFOAM® computational library. This talk aims to provide an overview of the computational rheology related work done at IPC/UMinho by a large group of researchers, in many cases in close cooperation with industry, and to report the advantages of using computational codes based on OpenFOAM® to support design activities

[extract] Objetives: explore the possibility of using Deep Learning (DL) techniques to evaluate the drag coefficient of small non-Brownian particles translating and settling in nonlinear viscoelastic fluids. The long-term objective is the development of a 3D numerical code for particle-laden viscoelastic flows (PLVF), which will contribute to understanding many advanced manufacturing and industrial operations, specifically the hydraulic fracturing process.

The extrudate swell, the geometrical modifications that take place when the flowing material leaves the confined flow inside a channel and moves freely without the restrictions promoted by the walls, is a relevant phenomenon in several polymer processing techniques. For instance, in profile extrusion, the extrudate cross-section suffers a number of distortions motivated by swell, which are very difficult to anticipate, especially for complex geometries. As happens in many industrial processes, numerical modelling might provide useful information to support design tasks, enabling to identify the best strategy to compensate the changes promoted by the extrudate swell. There are different ways to model free-surface flows, which can be grouped in Interface Tracking (IT) and Interface Capturing (IC) approaches. When dealing with steady state processes, which is the case of profile extrusion, IT is usually the best alternative, since it does not present the problems related to interface diffusion inherent to the IC approaches. OpenFOAM comprises a solver to simulate free-surface flows following an IT approach, which was proposed by Tukovic & Jasak (2008) and Tukovic et al., (2012). This work aims to assess the capability of that solver to simulate the extrudate swell process in profile extrusion, by using the interfaceTrackingFvMesh and interTrackMeshMotion libraries available in OpenFOAM-v1912 to track the free surface movement with a dynamic mesh motion. For this purpose, the data provided by Mitsoulis et al., (2012) on simulation of the extrudate swell of a Newtonian fluid at different Reynolds number flows is considered as the reference for validation., The authors would like to acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020 and UIDP/05256/2020, TSSiPRO - Technologies for Sustainable and Smart Innovative Products (NORTE-01-0145-FEDER-000015) and FAMEST - Footwear, Advanced Materials, Equipment’s and Software Technologies (POCI-01-0247-FEDER-024529). The authors also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER-000086) and Minho Advanced Computing Center (MACC).

The authors would like to acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020/UIDP/05256/2020 and TSSiPRO - Technologies for Sustainable and Smart Innovative Products (NORTE-01- 0145-FEDER-000015). The authors also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER-000086) and Minho Advanced Computing Center (MACC). M.M. Martins would like to thank also the support of the University Centre - Catholic of Santa Catarina (Brazil).

Presentation at 15th OpenFOAM Workshop, June 22-25, 2020, Arlington, VA, USA.

Rheology, defined as the science of deformation and flow of matter, is a multidisciplinary scientific field, covering both fundamental and applied approaches [...]

Understanding the behaviour of multiphase flows of solid in viscoelastic fluids is essential in several industrial applications, such as oil sands mining and polymer processing. For this aim, a novel numerical algorithm was implemented on an open-source finite-volume fluid flow solver coupled with an immersed boundary method, to allow the use of viscoelastic constitutive equations on the fluid (continuous) phase. To avoid numerical issues related to high Weissenberg number flows the log-conformation tensor approach can be employed on the newly developed algorithm. The accuracy of the algorithm was evaluated by studying several benchmark flows, namely: (i) the sedimentation of a sphere in a bounded domain surrounded by either Newtonian or viscoelastic fluids; (ii) rotation of a sphere in a homogeneous shear viscoelastic fluid flow; (iii) the cross-stream migration of a neutrally buoyant sphere in a steady Poiseuille flow, considering both Newtonian and viscoelastic suspending fluids. All the results obtained, on the referred case studies, allowed either to replicate the ones available on the published literature, or to describe additional effects promoted by the assumption of viscoelastic behaviour on the continuous phase. To illustrate the potential of the developed code, a newly case study of the shear-induced solid particle alignment in wall-bounded Newtonian and viscoelastic fluids was studied. The role of the fluid rheology and finite gap size on both the approach rate and pathways of the solid particles are described., This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. The authors would like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).

Injection moulding is one of the most important processing techniques for thermoplastic materials, and due to the high competition and product requirements, it demands continuous optimization. In industrial practice, aiming to minimize the resources spent on the design and manufacturing activities, it is common to resort to appropriate computational modelling tools. However, mainly due to the typical high cost of proprietary software, the support of computational modelling tools in injection moulding design related tasks is not available to medium and small sized companies. This framework, and the clear perspective of the benefit brought by computational modelling, has been motivating the development of codes based on open-source libraries, as happens with OpenFOAM computational library. This work aims to identify the computational framework employed by injection moulding codes well established in industry, and perform the required adaptations on the most appropriate solvers to replicate it in OpenFOAM. Then a few case studies will be employed to compare the predictions and performance of the proprietary and open source codes, This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UID/CTM/50025/2019 and PTDC/EMS-ENE/3362/2014. The authors would like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho (NORTE-07- 0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Polymer multilayer co-extrusion is a manufacturing process wherein two or more polymers feed a common extrusion die to form a layered product, aiming to combine in a synergic way the properties of the individual polymers comprising each layer [1]. The usual manufacturing approach starts by co-extruding two layers which are duplicated in each Interfacial Surface Generator Module (ISGM) employed, see Figure 1. This is achieved by dividing the flow of the two inlet layers (AB) in the division region, deforming and overlapping the two individual streams, which are subsequently joined in the junction region to reach a 4 layer structure (ABAB) [2]. In this way, each ISGM employed allows duplicating the number of layers in the final product., This work is funded by National Funds through FCT - Portuguese Foundation for Science and Technology, Reference UID/CTM/50025/2019. The authors would like also to thank the support of the Search Cluster, Project TSSIPRO - Portugal and University Centre - Catholic of Santa Catarina - Brazil.

One of the critical stages in the extrusion of thermoplastic profiles is the cooling of the profile, which is usually undertaken in a metallic calibrator. In order to assure the highest possible productivity, the profile thermal energy must be removed as fast as possible. However, due to the typical low diffusivity of thermoplastic materials, the cooling stage is relatively long and the temperature gradients along the profile thickness are high, promoting the development of thermal residual stresses, which should be minimized. Consequently, designing an optimum calibration system that ensures fast and low level of thermal residual stresses is always a difficult task, especially when dealing with complex geometry profiles. In this work, we firstly report the experimental assessment of a previously developed numerical modelling code [1], which is able to model the thermal interchanges that take place at the profile extrusion calibration stage, and was developed in the framework of the OpenFOAM® [2] computational library. This task is undertaken with an industrial case study: a cooling system, composed by three calibrators in series, used in the production of a swimming pool cover profile. The experimental data of the temperature evolution along the calibration length was found to be similar to the numerical predictions, with a maximum relative error of circa 8.6% near the inlet of the second calibrator unit, which allowed the numerical code validation. Upon the experimental assessment the numerical code was used to support the redesign of the calibration system. This study led to an alternative calibration system design, which has a simpler constructive solution and a better performance than the original one, considered in the validation of the numerical code. As main conclusions, the results reported in this work prove the accuracy of the numerical code developed to compute the temperature distribution in the cooling/calibration extrusion stage, and its suitability to support the design of these systems., This work is funded by UID/CTM/50025/2013 - LA0025, with the financial support of FCT/MEC through national funds and when applicable by FEDER co-funded, within the partnership agreement PT2020.

The ability to simulate the behavior of dilute suspensions, considering Eulerian-Lagrangian approaches, requires proper drag models, which should be valid for a wide range of process and material parameters. These drag models allow to calculate the momentum exchange between the continuous and dispersed phases. The currently available drag models are only valid for inelastic constitutive fluid models. This work aims at contributing to the development of drag models appropriate for dilute suspensions, where the continuous phase presents viscoelastic characteristics. To this aim, we parametrize the effects of fluid elasticity, namely, the relaxation and retardation times, as well as inertia on the drag coefficient of a sphere translating through a viscoelastic fluid, described by the Oldroyd-B model. To calculate the drag coefficient we resort to three-dimensional direct numerical simulations of unconfined viscoelas tic flows past a stationary sphere, at different Reynolds number, Re, over a wide range of Deborah numbers (< 9), and the polymer viscosity ratios. For low Re (< 1), we identified a non-monotonic trend for the drag coefficient correction (the ratio between the calculated drag coefficient and the one obtained for Stokes-flow). It initially decreases with the increase of De, for low De values (< 1), which is followed by a significant growth, due to the large elastic stresses that are developed on both the surface and wake of the sphere. These behaviors, observed in the inertia less flow regime, are amplified as the polymer viscosity ratio approaches unity. At higher Re (> 1), the drag coefficient correction is found to be always bigger than unity, but smaller than the enhancement calculated in creeping flow limit., The authors would like to acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UID/CTM/50025/2013 and POCI-01-0247-FEDER-017656.

Fluid-particle transport systems present a significant practical relevance, in several engineering applications, such as oil sands mining and polymer processing. In several cases it is essential to consider that the fluid, in which the particles are dispersed, has underlying viscoelastic characteristics. For this aim, a novel numerical algorithm was implemented on an open-source finite-volume viscoelastic fluid flow solver coupled with an immersed boundary method, by extending the open-source computational fluid dynamics library CFDEMcoupling. The code is able to perform fully-resolved simulations, wherein all flow scales, associated with the particle motion, are resolved. Additionally, the formulation employed exploits the log-conformation tensor approach, to avoid high Weissenberg number issues. The accuracy of the algorithm was evaluated by studying several benchmark flows, namely: (i) the sedimentation of a sphere in a bounded domain; (ii) rotation of a sphere in simple shear flow; (iii) the cross-stream migration of a neutrally buoyant sphere in a steady Poiseuille flow. In each case, a comparison of the results obtained with the newly developed code with data reported in the literature is performed, in order to assess the code accuracy and robustness. Finally, the capability of the code to solve a physical challenging problem is illustrated by studying the interactions and flowinduced alignment of three spheres in a wall-bounded shear flow. The role of the fluid rheology and finite gap size on both the approach rate and pathways of the solid particles are described [1]., This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. The authors would like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).

Injection moulding is one of the most important processing techniques for thermoplastic materials, and, due to the high competition and product requirements, it demands continuous optimization. In industrial practice, aiming to minimize the resources spent on the design and manufacturing activities, it is common to resort to appropriate computational modelling tools. However, mainly due to the typical high cost of proprietary software, the support of computational modelling tools in injection moulding design related tasks is not available to medium and small sized companies. This framework, and the clear perspective of the benefits brought by computational modelling, has been motivating the development of codes based on open-source codes, as happens with OpenFOAM [1] computational library. This work aims to compare the numerical results obtained by an open-source solver with the ones obtained with the proprietary software Moldex3D [2], widely employed in in dustry. The case of study considered is the filling stage of the injection moulding process of a rectangular cavity for a thermoplastic material modeled with a non-isothermal, inelastic and generalized Newtonian constitutive model., This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UID/CTM/50025/2013 and PTDC/EMS-ENE/3362/2014. The authors would like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).

This work presents a simple procedure for balancing the flow in extrusion dies. The method consists in using different temperatures on the different sides of the extrusion die surface, in this way altering the local viscosity of the polymer melt, and thus the melt flow distribution. The design methodology follows a numerical trial-and-error procedure (implemented in OpenFOAM (R)), which was assessed with an industrial case study (swimming pool cover profile). The results obtained show that the support of computational tools is an excellent design aid, and a much better alternative to the experimental trial-and-error procedure commonly used in industry., The authors would like to thank for the funding by FEDER through the COMPETE 2020 Programme, the National Funds through FCT-Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. L.L. Fends would also like to thank for the funding from FCT through the scholarship SFRH/BPD/100353/2014. The authors would also like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho, (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).

This work reports the developments made in improving the numerical stability of the viscoelastic solvers available in the open-source finite volume computational library OpenFOAM (R). For this purpose, we modify the usual both-side diffusion (BSD) technique, using a new approach to discretize the explicit diffusion operator. Calculations performed with the new solver, for two benchmark 2D case studies of an upper-convected Maxwell (UCM) fluid, are presented and compared with literature results, namely the 4:1 planar contraction flow and the flow around a confined cylinder. In the 4:1 planar contraction flow, the corner vortex size predictions agree well with the literature, and a relative error below 5.3% is obtained for De, This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013 and under the scholarship SFRH/BPD/100353/2014. The author M.S.B. Araujo acknowledges funding from CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior) proc. BEX 1902-14-8. The authors would like to acknowledge the Minho University cluster under the project Search-ON2: Revitalization of HPC infrastructure of UMinho, (NORTE-07-0162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF).

The development of additive manufacturing processes, such as selective laser melting (SLM), has signifcantly extended the options for manufacturing extrusion heads. Extrusion head designs can now be realized with very slender geometries, which not only have integrated mixer functions, thereby improving the melt homogeneity, but can also be used to attach the mandrel to the head. This allows compact heads to be manufactured with a very high potential for saving operating costs., (undefined)

Multiphase flows are relevant in several industrial processes mainly because they are present in the production of a large diversity of products. Hence, the availability of accurate numerical modeling tools, able to cope with this type of flows, is of major significance to provide detailed information about the system characteristics, in order to guide the design activity. This study presents a detailed assessment of a multiphase flow solver able to couple Eulerian and Lagrangian phases, the last modeled through the discrete particle method. The numerical code is already implemented in the open source computational fluid dynamics software package OpenFOAM ®. The solver (DPMFoam) is firstly used to simulate the collision between two particles, for which a good correlation was obtained with the theoretical impulse force value. Subsequently, the solver is employed in the simulation of a pseudo 2D gas-solid flow in a fluidized bed. In this case study, the results obtained for the bubble patterns, time-average flow patterns, bed expansion dynamics and particle phase energy analysis are in agreement with the experimental and numerical results available in the literature. In addition, the numerical pressure drop for the fluidized bed is computed and compared with the analytical Ergun’s pressure drop equation. The accuracy of the numerical results was found to be sensitive to the solid fraction estimation., This work is funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT Portuguese Foundation for Science and Technology under the project EXPL/CTM-POL/1299/2013. In addition, the authors would like to acknowledge the Minho University cluster under the project SearchON2: Revitalization of HPC infractructure of Minho, (NORTE-070162-FEDER-000086), co-funded by the North Portugal Regional Operational Programme (ON.2-0 Novo Norte), under the National StrategicReferenceFramework(NSRF),throughtheEuropeanRegional Development Fund (ERDF)., info:eu-repo/semantics/publishedVersion

This work presents a brief introduction to fractional calculus and its application to some problems in rheology. We present two different viscoelastic models based on fractional derivatives (the Fractional Maxwell Model - FMM and the Fractional Viscoelastic Fluid - FVF) and discuss their reduction to the classical Newtonian and Maxwell fluids. A third model is also studied (an extension of the FMM to an invariant form), being given by a combination of the K-BKZ integral model with a fractional memory function which we denote the Fractional K-BKZ model. We discuss and illustrate the ability of these models to fit experimental data, and present numerical results for simple stress relaxation following step strain and steady shearing., L.L. Ferris and J.M. Nobrega would like to thank the funding by FEDER through the COMPETE 2020 Programme, the National Funds through FCT - Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. L.L. Ferias would also like to thank the funding by FCT through the scholarship SFRH/BPD/100353/2014. M.L. Morgado would like to thank the funding by FCT through Project UID/MAT/00013/2013 and M. Rebelo would also like to thank the funding by FCT through Project UID/MAT/00297/2013 (Centro de Matematica e Aplicacoes)., info:eu-repo/semantics/publishedVersion

The usual high cost of commercial codes, and some technical limitations, clearly limits the employment of numerical modelling tools in both industry and academia. Consequently, the number of companies that use numerical code is limited and there a lot of effort put on the development and maintenance of in-house academic based codes. Having in mind the potential of using numerical modelling tools as a design aid, of both products and processes, different research teams have been contributing to the development of open source codes/libraries. In this framework, any individual can take advantage of the available code capabilities and/or implement additional features based on his specific needs. These type of codes are usually developed by large communities, which provide improvements and new features in their specific fields of research, thus increasing significantly the code development process. Among others, OpenFOAM® multi-physics computational library, developed by a very large and dynamic community, nowadays comprises several features usually only available in their commercial counterparts; e.g. dynamic meshes, large diversity of complex physical models, parallelization, multiphase models, to name just a few. This computational library is developed in C++ and makes use of most of all language capabilities to facilitate the implementation of new functionalities. Concerning the field of computational rheology, OpenFOAM® solvers were recently developed to deal with the most relevant differential viscoelastic rheological models, and stabilization techniques are currently being verified. This work describes the implementation of a new solver in OpenFOAM® library, able to cope with integral viscoelastic models based on the deformation field method. The implemented solver is verified through the comparison of the predicted results with analytical solutions, results published in the literature and by using the Method of Manufactured Solutions.

This work reports the implementation and verification of a new so lver in OpenFOAM® open source computational library, able to cope with integral viscoelastic models based on the integral upper-convected Maxwell model. The code is verified through the comparison of its predictions with analytical solutions and numerical results obtained with the differential upper-convected Maxwell model, CAPES, FCT projects PEsT-C/CTM/LA0025/2013, PTDC/MAT/121185/2010 and FEDER

In this work we develop a new mathematical model for the Pennes’ bioheat equation assuming a fractional time derivative of single order. A numerical method for the solu- tion of such equations is proposed, and, the suitability of the new model for modelling real physical problems is studied and discussed, COMPETE, FEDER and Fundação para a Ciência e a Tecnologia (the Portuguese Foundation for Science and Technology (FCT)) through Projects UID/CTM/50025/2013, PTDC/EME- MFE/113988/2009 and EXPL/CTM-POL/1299/2013. M. Rebelo acknowledge financial funding by the Portuguese Foundation for Science and Technology through the project PEstOE/MAT/UI0297/2013 (Centro de Matemática e Aplicacões)

This paper presents part of a study aimed at finding a suitable, yet cost-effective, surface finish for a steel structure subject to the car washing environment and corrosive chemicals. The initial, life cycle and average equivalent annual (AEAC) costs for surface finishing methods were calculated for a steel structure using the LCCC algorithm developed by American Galvanizers Association (AGA). The cost study consisted of 45 common surface finish systems including: hot-dip galvanization (HDG), metallization, acrylic, alkyd and epoxy as well as duplex coatings such as epoxy zinc and inorganic zinc (IOZ). The results show that initial, life cycle and AEAC costs for hot dip galvanization are the lowest among all the other methods, followed by coal tar epoxy painting. The annual average cost of HDG for this structure was estimated about €0.22/m2, while the other cost-effective alternatives were: IOZ, polyurea, epoxy waterborne and IOZ/epoxy duplex coating., This project was financed by the Portuguese Foundation for Science and Technology, FCT, (SFRH/BD/51105/2010) and FEDER, via FCT, under the PEstC/CTM/LA0025/2011 (Strategic Project LA 25 - 2011-2012). The authors would also like to acknowledge the support of Petrotec and MIT Portugal program throughout this work.

Understanding the behavior of c omplex composite materials using mixing procedures is fundamental in several industrial processes. For instance, polymer composites are usually manufactured using dispersion of fillers in polymer melt matrices. The success of the filler dispersion depends both on the complex flow patterns generated and on the polymer melt rheological behavior. Consequently, the availability of a numerical tool that allow to model both fluid and particle would be very useful to increase the process insight. Nowadays there ar e computational tools that allow modeling the behavior of filled systems, taking into account both the behavior of the fluid (Computational Rheology) and the particles (Discrete Element Method). One example is the DPMFoam solver of the OpenFOAM ® framework where the averaged volume fraction momentum and mass conservation equations are used to describe the fluid (continuous phase) rheology, and the Newton’s second law of motion is used to compute the particles (discrete phase) movement. In this work the refer red solver is extended to take into account the elasticity of the polymer melts for the continuous phase. The solver capabilities will be illustrated by studying the effect of the fluid rheology on the filler dispersion, taking into account different fluid types (generalized Newtonian or viscoelastic) and particles volume fraction and size. The results obtained are used to evaluate the relevance of considering the fluid complex rheology for the prediction of the composites morphology

The usual high cost of commercial codes, and some technical limitations, clearly limits the employment of numerical modelling tools in both industry and academia. Consequently, the number of companies that use numerical code is limited and there a lot of effort put on the development and maintenance of in-house academic based codes . Having in mind the potential of using numerical modelling tools as a design aid, of both products and processes, different research teams have been contributing to the development of open source codes/libraries. In this framework, any individual can take advantage of the available code capabilities and/or implement additional features based on his specific needs. These type of codes are usually developed by large communities, which provide improvements and new features in their specific fields of research, thus increasing significantly the code development process. Among others, OpenFOAM® multi-physics computational library, developed by a very large and dynamic community, nowadays comprises several features usually only available in their commercial counterparts; e.g. dynamic meshes, large diversity of complex physical models, parallelization, multiphase models, to name just a few. This computational library is developed in C++ and makes use of most of all language capabilities to facilitate the implementation of new functionalities. Concerning the field of computational rheology, OpenFOAM® solvers were recently developed to deal with the most relevant differential viscoelastic rheological models, and stabilization techniques are currently being verified. This work describes the implementation of a new solver in OpenFOAM® library, able to cope with integral viscoelastic models based on the deformation field method. The implemented solver is verified through the comparison of the predicted results with analytical solutions, results published in the literature and by using the Method of Manufactured Solutions

[Excerpt] A large number of constitutive equations were developed for viscoelastic fluids, some empirical and other with strong physical foundations. The currently available macroscopic constitutive equations can be divided in two main types: differential and integral. Some of the constitutive equations, e.g. Maxwell are available both in differential and integral types. However, relevant in tegral models, like K - BKZ, just possesses the integral form. (...)

Understanding the mixing process of complex composite materials is fundamental in several industrial processes. For instance, the dispersion of fillers in polymer melt matrices is commonly employed to manufacture polymer composites, using a twin-screw extruder. The effectiveness of the filler dispersion depends not only on the complex flow patterns generated, but also on the polymer melt rheological behavior. Therefore, the availability of a numerical tool able to predict mixing, taking into account both fluid and particles phases would be very useful to increase the process insight, and thus provide useful guidelines for its optimization. In this work, a new Eulerian-Lagrangian numerical solver is developed OpenFOAM® computational library, and used to better understand the mechanisms determining the dispersion of fillers in polymer matrices. Particular attention will be given to the effect of the rheological model used to represent the fluid behavior, on the level of dispersion obtained. For the Eulerian phase the averaged volume fraction governing equations (conservation of mass and linear momentum) are used to describe the fluid behavior. In the case of the Lagrangian phase, Newton’s second law of motion is used to compute the particles trajectories and velocity. To study the effect of fluid behavior on the filler dispersion, several systems are modeled considering different fluid types (generalized Newtonian or viscoelastic) and particles volume fraction and size. The results obtained are used to correlate the fluid and particle characteristics on the effectiveness of mixing and morphology obtained.

[Extrat] Multiphase flows are relevant in several industrial processes, thus the availability of accurate numerical modeling tools, able to support the design of products and processes, is of much significance. OpenFOAM version 2.3.x comprises a multiphase flow solver able to couple Eulerian and Lagrangian phases using the discrete particles method (DPM), the DPMFoam. In this work the DPMFoam solver is assessed by comparing its predictions with analytical results and experimental and simulated data available in the literature. They are results from Goldschmidt’s [1] and Hoomans’s [2] theses and the analytical Ergun equation. The goal was to define accuracy and performance of DPMFoam in general scientific or commercial applications. Obtained results demonstrate a good agreement with the reference simulation data and is within reasonable deviations from the experimental values. (...)

Neste trabalho, multifilamentos ocos de polipropileno foram estudados com o objetivo de construir um fantoma cerebral adequado à validação e controlo de qualidade de uma modalidade de imagem clínica inovadora: High-Definition Fiber Tractography. Foram investigadas e discutidas a análise à secção transversal e a redução da área de multifilamentos ocos de polipropileno, através de estiramento. De acordo com os resultados experimentais, a dimensão da secção transversal dos multifilamentos é proporcional à massa linear dos mesmos, existindo uma irregularidade, relativamente, à forma deste tipo de materiais., Este trabalho é apoiado pela bolsa de doutoramento SFRH/BD/90324/2012 da Fundação para a Ciência e Tecnologia

[Extrat] Thermoplastic profiles are very attractive due to their inherent design freedom. However, the usual methodologies employed to design extrusion forming tools, based on experimental based trial–and–error procedures, are highly dependent on the designer’s experience and lead to high resources consumption. Despite of the relatively low cost of the raw materials employed on the production of this type of profiles, the resources involved in the die design process significantly increase their cost. These difficulties are even more evident when a complex geometry profile has to be produced and there is no previous experience with similar geometries. Therefore, novel design approaches are required, in order to reduce the required resources and guarantee a good performance for the produced profile. (...)

Poly(lactic acid) (PLA), was mixed with wood fibers, coffee grounds, fertilizer and a foaming agent to developed a ecofriendly material to be used in horticulture. The developed materials should have mechanical properties similar to PLA, increasing biodegradability and lower price. The materials were prepared by melt processing in an internal mixer at 190ºC and were characterized by several techniques. The mechanical properties of the bio-composites, measured by flexural tests, were similar to neat PLA even with a reduction of 40 wt. % of polymer. Biodegradation assessment by composting tests in aerobic environment demonstrated that the green materials developed exhibited higher biodegradability than PLA. Bio-composites containing wood fibers and fertilizer revealed to be the most suitable for horticulture application, since these can combine mechanical properties, biodegradability and fertilizer release. Moreover, this green material has two main advantages, it can be prepared using materials from natural resources and does not generate any residue after use.

Biodegradable poly(lactic) acid (PLA)/clay nanocomposites were investigated to be used as food packaging material. Several techniques were used, rheology, mechanical, gel permeation chromatography (GPC), contact and biodegradability tests, to characterize the developed materials. The addition of organoclay improved PLA mechanical and biodegradable properties. Food contact test showed that the nanocomposites are able to be used as food packaging materials.