OpenFOAM®

This paper describes a self-contained, partitioned fluid–structure interaction solver based on a finite volume discretisation. The incompressible fluid flow is described by the Navier–Stokes equations in the arbitrary Lagrangian–Eulerian form and the solid deformation is described by the St. Venant-Kirchhoff hyperelastic model in the total Lagrangian form. Both fluid and solid are discretised in space using the second-order accurate cell-centred finite volume method, and temporal discretisation is performed using the first-order accurate implicit Euler scheme. Coupling between fluid and solid is performed using a Robin-Neumann partitioned procedure based on a new Robin boundary condition for pressure. The solver has been tested on the wave propagation in an elastic tube test case characterised by a low solid-to-fluid density ratio. The first-order temporal accuracy is shown and the stability of the method is demonstrated for both the strongly coupled and loosely coupled versions of the solution procedure. It is also shown that the proposed methodology can efficiently handle FSI cases in which the fluid domain is entirely enclosed by Dirichlet boundary conditions, even for the case of geometrically nonlinear elastic deformation.

Manipulating CAD geometry using primitive components rather than the originating software is typically a challenging prospect. The parameterisation used to define the geometry of a model is often integral to the efficiency of the design. Even more crucial are the relations (constraints) between those parameters that do not allow the model to be under-defined. However, access to these parameters is lost when making the CAD model portable. Importing a standard CAD file gives access to the Boundary Representation (BRep) of the model and consequently its boundary surfaces which are usually trimmed patches. Therefore, in order to connect Adjoint optimization and Computational Fluid Dynamics to the industrial design framework (CAD) in a generic manner, the BRep must be used as a starting point to produce volume meshes and as a means of changing a model’s shape. In this study, emphasis is given firstly, to meshing (triangulation) of a BRep model as a precursor to volume meshing and secondly, to the use of techniques similar to Free Form Deformation for changing the model’s shape.

The efficiency of control valves operating with liquids is highly conditioned by the occurrence of cavitation when they undergo large pressure drops. For severe service control valves, the subsequent modification of their performance can be crucial for the safety of an installation. In this work, the solver interPhaseChangeFoam, implemented in OF v2.3, is used to characterize the flow in a globe valve, with the objective to evaluate its capability in solving cavitating flows in complex 3D geometries. An Homogeneous Equilibrium approach is adopted, and phase change is modeled using the Schnerr and Sauer cavitation model. Confrontation with experimental data is carried out in order to validate the numerical results. It is found that the solver predicts correctly the location of vapor cavities, but tends to underestimate their extension. The flow rate is correctly calculated, but in strong cavitating regimes, it is affected by the underprediction of vapor cavities. The force acting on the stem is found to be more sensitive to the computation parameters.

Tidal estuaries represent a significant and accessible source of renewable energy for modern society. The regular nature of the tides makes this a valuable resource to exploit. Tidal turbines that extract energy from tidal currents would be one way to do this. The shallow nature of estuaries suggests that these would need to be low power units linked together in large farms, and the modelling and optimisation of such farms of turbines is a significant challenge. In this chapter, I report on a major research effort to model a possible turbine, the AquaScientific Lift/Drag turbine, and the development from this of a simplified CFD model, the Immersed Body Force method, to allow for simulation of small arrays. Following from this, I report on the development of surrogate modelling techniques to allow the prediction of outputs from larger arrays and optimisation using Genetic Algorithm techniques.

This chapter presents a combination of an OpenFOAM $$^{\textregistered }$$ -based continuous adjoint solver and a Radial Basis Function (RBF)-based morpher forming a software suite able to tackle shape optimization problems. The adjoint method provides a fast and accurate way for computing the sensitivity derivatives of the objective functions (here, drag and lift forces) with respect to the design variables. The latter control a group of RBF control points used to deform both the surface and volume mesh of the CFD domain. The use of the RBF-based morpher provides a fast and robust way of handling mesh and geometry deformations with the same tool. The coupling of the above-mentioned tools is used to tackle shape optimization problems in automotive and aerospace engineering. This work was funded by the RBF4AERO “Innovative benchmark technology for aircraft engineering design and efficient design phase optimisation” project funded by the EU 7th Framework Programme (FP7-AAT, 2007-2013) under Grant Agreement No. 605396 and the presented methods are available for use through the RBF4AERO platform ( www.rbf4aero.eu ).

There has been a significant amount of work on modelling erosion caused by slurries, however, these studies are normally focused on low concentrations. The reason for this is usually that dense slurries are too computationally expensive to model in the Euler-Lagrange frame. This presentation suggests a novel solution for reducing computational effort using OpenFOAM to combine two solvers. The two phases of the bulk flow are modelled, partially in the Eulerian-Eulerian reference frame, and partially in the Eulerian-Lagrangian frame. The method aims to increase computational efficiency, but still keep the necessary particle impact data at the wall required for erosion modelling. The new model consists of splitting the domain into two regions and using patch interpolation to couple them together. The particles are then injected into the second region by using the values of the second Eulerian phase from the first region. The values of the second Eulerian phase are written at every time step to a lookupTable, enabling the solver to be used in conjunction with geometry changes, etc., as in Lopez’s work (Lopez in LPT for erosion modelling in OpenFOAM 2014, [1]). If the process can be validated, it provides a promising step towards modelling dense slurry erosion.

The following chapter presents a new approach for the development of turbulent models, with potential application to the design of liquid fuel nuclear reactors. To begin the chapter, the work being carried out at LPSC (Grenoble) for validating the modeling of molten salt coolants is presented, alongside a Backward-Facing Step (BFS) geometry, which will be studied throughout this work. In the subsequent section, various turbulence models are evaluated in the BFS and their advantages and limitations are analyzed, with the conclusion that some improvements in the turbulence modeling are necessary. Therefore, the next section introduces a methodology for developing a nonlinear closure for turbulence models by means of Symbolic Regression via Genetic Evolutionary Programming (GEATFOAM). Then, this new methodology is implemented for direct numerical simulation data of the BFS, obtaining a new nonlinear closure for the standard k– $$\varepsilon $$ model. Finally, the new model is compared against classical turbulence models for the BFS, and, then, the extrapolability of this model is analyzed for available experimental data of an axial expansion in a pipe. Encouraging results are obtained in both cases.

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 $$^{\circledR }$$ ), 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 production and handling of non-spherical granular products plays an important role in many industries. It is often necessary to consider the real particle shape of the real particles as an essential prerequisite for modeling these processes reliably. This work presents a new approach for approximating the drag coefficient of non-spherical particles during simulation. This is based on the representation of the particle shape as a clump of multiple spheres, as it is often used in the Discrete Element Method (DEM). The paper describes the calculation of the drag coefficient based on the arrangement of the spheres within the clump depending on the Reynolds number and the flow direction. Numerical simulations of the flow around regularly- and irregularly shaped particles, as well as experiments in a wind tunnel, are used as the basis of model development. The new drag model is able to describe the drag coefficient for irregularly shaped particles within a wide range of Reynolds numbers. It has been implemented in the toolbox CFDEM $$^{\textregistered }$$ coupling. The new drag model is tested within CFD-DEM simulations of particle behavior in a spouted bed.

Even though free surface flows are of high importance in a number of engineering areas, they still pose a challenging problem from the point of view of Computational fluid dynamics (CFD) modeling. In the present work, a Volume-of-fluid (VOF) method-based open source CFD solver, interFoam, is used to study the properties of a gravity-driven liquid flow on an inclined plate with respect to different plate textures. At first, the proposed model was validated against the available experimental data. Then, the effects of three different types of texture on the specific wetted area of the plate were evaluated.

Turbomachinery simulations represent one of the most challenging fields in Computational Fluid Dynamics (CFD). In recent years, the general CFD capabilities of foam-extend have been extended by introducing and maintaining additional features specifically needed for turbomachinery applications, with the aim of offering a high-quality CFD tool for the study of rotating machinery. This work presents the implementation and validation of new capabilities for turbomachinery with foam-extend, a community-driven fork of OpenFOAM $$^{\textregistered }$$ . The formulation of an energy equation more convenient for compressible turbomachinery applications has resulted in the rothalpy equation. Rothalpy is a physical quantity conserved over a blade row, stator or rotor, but not over a stage, both stator and rotor. It is fundamental to take into account that the value of rothalpy is not continuous across the rotor–stator interface, due to the change of rotational speed between zones. The rothalpy equation has been derived for both relative and absolute frames of reference, showing that additional terms appear in the absolute frame of reference. Moreover, additional functionality has been added to the rotor–stator interface boundary conditions’ General Grid Interface (GGI), partial Overlap GGI and Mixing Plane Interface, in order to account for the rothalpy jump. The development of these new capabilities and their validation are shown, as well as industrial applications of compressible turbomachinery flows.

Wave energy conversion is an active field of research, aiming to harness the vast amounts of energy present in ocean waves. An essential development trajectory towards an economically competitive wave energy converter (WEC) requires early device experimentation and refinement using numerical tools. OpenFOAM $$^{\textregistered }$$ is proving to be a useful numerical tool for WEC development, having been increasingly employed in recent years to simulate and analyse the performance of WECs. This chapter reviews the latest works employing OpenFOAM $$^{\textregistered }$$ in the field of wave energy conversion, and then presents the new application, of evaluating energy maximising control systems (EMCSs) for WECs, in an OpenFOAM $$^{\textregistered }$$ numerical wave tank (NWT). The advantages of using OpenFOAM $$^{\textregistered }$$ for this application are discussed, and implementation details for simulating a controlled WEC in an OpenFOAM $$^{\textregistered }$$ NWT are outlined. An illustrative example is given, and results are presented, highlighting the value of evaluating EMCSs for WECs in an OpenFOAM $$^{\textregistered }$$ NWT.

In OpenFOAM $$^{\textregistered }$$ , the powerful CFD solver can be combined with an electrostatic solver, allowing multiphysics analysis on the same mesh within the same numerical framework, which offers advantages for applications in high voltage power devices. One important piece of missing functionality in OpenFOAM $$^{\textregistered }$$ is a boundary condition for the electrostatic solver that can apply a floating potential to conducting parts that are not connected to any fixed potential and should be treated as an equipotential surface of undefined potential. This chapter describes the theoretical background and an OpenFOAM $$^{\textregistered }$$ implementation of a numerical algorithm that can accurately solve the electrostatic problem for a domain that includes several floating potentials.

For the description of the filling, packing, and cooling phases of the injection molding process, a simulation framework of a compressible two-phase fluid model with polymer-specific material models is established and validated with experimental results. With this approach, it is possible to describe the fluid dynamic, the rheological, and the thermal behavior of the material during the production process. The main focus of this work is on the description of the standard injection molding process of common thermoplastic materials for industrial application, with special focus on process relevant quantities, e.g., pressure, temperature, as these values are of utmost importance for understanding the underlying phenomena and comparing the results to experimentally measured values.

Induction processing technology is widely applied in the metallurgical and crystal growth industry where conducting or semi-conducting material is involved. In many applications, alternating magnetic fields, which are used to generate heat and force, occur together with a free-surface flow. The numerical analysis of such three-dimensional, multi-physical phenomena on the industrial scale is still a big challenge. We present an overview of a novel multi-mesh model for addressing these kinds of coupled problems by means of computational simulations. It is based on the Finite Volume Method (FVM) of the software foam-extend ( http://www.foam-extend.org )—an extended version of OpenFOAM $$^{\textregistered }$$ (Weller et al. in Computational Physics 12(6):620–631, 1998, [15]). Our development is motivated by the desire to investigate the so-called Ribbon Growth on Substrate (RGS) process. RGS is a crystallisation technique that allows for the production of silicon wafers and advanced metal silicide alloys Schönecker et al. (Solid State Phenomena 95-96:149-158 2004, [12]) with high volume manufacturing and outstanding material yield.

A multi-physics solver for nuclear reactor analysis, named GeN-Foam (Generalized Nuclear Foam), has been developed by the Laboratory for Reactor Physics and System Behavior at the EPFL and at the Paul Scherrer Institut (Switzerland). The developed solver couples: a multigroup neutron diffusion or SP3 sub-solver; a thermal-hydraulics sub-solver based on the standard k-ε turbulence model, but extended to coarse-mesh applications through the use of a porous medium approach for user-selected cell zones; a displacement-based thermal-mechanics sub-solver to evaluate thermal deformations of structures; and a finite-difference subscale fuel model that can be used in coarse-mesh simulations of the core to evaluate the local temperature profile in fuel and cladding. A first-order implicit Euler scheme with an adaptive time step is used for time integration, and the coupling between equations is semi-implicit, using the Picard iteration. Three different meshes are used for thermal-hydraulics, thermal-mechanics and neutron diffusion, and fields are projected between different meshes through a standard volume-averaging technique. GeN-Foam features a general applicability to pin- or plate-fuel, or homogeneous nuclear reactors. Its application in several cases of interest has shown stable numerical behavior, the possibility of obtaining reliable results for traditional reactor types, as well as the possibility of investigating non-conventional reactors, whose analysis cannot be easily carried out using nuclear legacy codes.

The Harmonic Balance Method for nonlinear periodic flows is presented in this paper. Assuming a temporally periodic flow, a Fourier transformation is deployed in order to formulate a transient problem as a multiple quasi-steady-state problem. A solution of the obtained equations yields flow fields at discrete instants of time throughout a representative harmonic period, while still capturing the transient effect. The method is implemented in foam-extend, a community-driven fork of OpenFOAM $$^{\textregistered }$$ and developed for multi-frequential use in turbomachinery applications. For validation, a 2D turbomachinery test case is used. Pump head, efficiency, and torque obtained with Harmonic Balance will be compared to a transient and steady-state simulation. Furthermore, pressure contours on rotor blades will be compared. And finally, in order to present the method’s efficiency along with its accuracy, a CPU time comparison will also be presented.

The mathematical modelling and numerical simulation of multiphase flows are both demanding and highly complex. In typical problems with industrial relevance, the fluids are often in non-isothermal conditions, and interfacial phenomena are a relevant part of the problem. A number of effects resulting from the presence of temperature differences must be adequately taken into account to make the results of numerical simulations consistent and realistic. Moreover, in general, gradients of surface tension at the interface separating two liquids are a source of numerical issues that can delay (and in some circumstances even prevent) the convergence of the solution algorithm. Here, we propose a fundamental and concerted approach for the simulation of the typical dynamics resulting from the presence of a dispersed phase in an external matrix under non-isothermal conditions based on the modular computer-aided design, modelling and simulation capabilities of the OpenFOAM® environment. The resulting framework is tested against the migration of a droplet induced by thermocapillary effects in the absence of gravity. The simulations are fully three-dimensional and based on an adaptive mesh refinement (AMR) strategy. We describe in detail the countermeasures taken to circumvent the problematic issues associated with the simulation of this kind of flow.

Formulation of implicitly coupled incompressible and compressible pressure–velocity solvers is presented in this paper. The formulation is an alternative to commonly used segregated solvers, in which inter-equation coupling is resolved by Picard iterations. In the coupled solver, the momentum and continuity (pressure) equations are solved simultaneously, in a single block matrix. Turbulence model equations and energy equation in compressible flow are solved in a segregated manner. The formulation is based on deriving the pressure equation as a Schur complement, including the Rhie–Chow correction. A new formulation of the compressible pressure-based solver is proposed by assuming an isentropic compression/expansion, resulting in consistent reduction of the compressible form to incompressible form.

This work reports the developments made in improving the numerical stability of the viscoelastic solvers available in the open-source finite volume computational library $$OpenFOAM^{\textregistered }$$ . 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 $$De \le 5$$ . In the flow around a confined cylinder, the predictions of the drag coefficient on the cylinder are similar to reference data, with a relative error below $$0.16 \%$$ for $$De \le 0.9$$ .

In a recent publication, we presented a novel geometric VOF interface advection algorithm, denoted isoAdvector (Roenby et al. in R Soc Open Sci 3:160405 2016, [1]). The OpenFOAM $$^{\textregistered }$$ implementation of the method was publicly released to allow for more accurate and efficient two-phase flow simulations in OpenFOAM $$^{\textregistered }$$ (Roenby in isoAdvector www.github.com/isoadvector , [2]). In the present paper, we give a brief outline of the isoAdvector method and test it with two pure advection cases. We show how to modify interFoam so as to use isoAdvector as an alternative to the currently implemented MULES limited interface compression method. The properties of the new solver are tested with two simple interfacial flow cases, namely the damBreak case and a steady stream function wave. We find that the new solver is superior at keeping the interface sharp, but also that the sharper interface exacerbates the well-known spurious velocities in the air phase close to an air–water interface. To fully benefit from the accuracy of isoAdvector, there is a need to modify the pressure–velocity coupling algorithm of interFoam, so it more consistently takes into account the jump in fluid density at the interface. In our future research, we aim to solve this problem by exploiting the subcell information provided by isoAdvector.

Several approaches have been developed to simulate liquid-jet atomization phenomena. Despite recent developments in numerical methods and computer performance, direct numerical simulation of the atomization process remains inaccessible for practical applications. Therefore, to carry out numerical simulations of the injected liquid from the internal flow within flow as far as the final dispersed spray, a modeling strategy has been developed. It is composed of a set of models implemented within the open-source software $$\texttt {OpenFOAM}^{\textregistered }$$ . First, the so-called Euler–Lagrange Spray Atomization (ELSA) approach is introduced. This is Eulerian formulation dedicated to jet atomization that is based on the analogy of turbulent mixing in a flow with variable density in the limit of infinite Reynolds and Weber numbers. Second, ELSA’s extension to a Quasi-Multiphase Eulerian (QME) approach is proposed. This method solves the problem of a second-order closure in modeling the turbulent liquid flux, hence solving the slip velocity between the phases. Third, an enhanced version of ELSA coupling with an Interface Capturing Method (ICM) and a Lagrangian approach for the final spray are introduced.

A numerical method for calculating lubricated contact pressures and friction in cold metal rolling is presented in this study. In order to have a good representation of the contact phenomena in lubricated metal rolling processes, the interaction between the surface roughness and lubricant flow has to be taken into account. Due to the changes in lubricant thickness during the rolling process, the lubricant flows in four local regimes: hydrodynamic thick film, hydrodynamic thin film, mixed and boundary lubrication regimes. The ability to treat all four lubrication regimes is required. Surface roughness effects, lubrication regimes treatment and lubricant property variations are all implemented within the present model. In order to calculate contact pressures and frictional forces, the Greenwood-Williamson model with the modified Reynolds lubrication equation is used. The Finite Area Method is used to discretize the Reynolds lubrication equation over a curved surface mesh. The implemented model is used as a solid contact boundary condition for a large strain hyperelastoplastic deformation solver developed in the foam-extend framework. The model is tested on wire and sheet rolling cases, and the results are presented here.

The present work aims to verify the applicability of Irwin probes and Preston tubes to turbulent incompressible flow in smooth rectangular ducts. For the experimental apparatus, an aspect ratio of 1:2 is considered and tests are conducted for Reynolds number values within the range of 104 to 9 × 104. Local friction coefficients are determined based on the pressure measurements obtained using pressure taps and a Preston tube. A linear relation is established between the local wall shear stress $$ (\tau_{{w_{x} }} ) $$ and the pressure difference $$ {(\Delta }p_{I} ) $$ measured with the Irwin probes. The numerical simulations implemented in the open source OpenFOAM® 2.4.0 CFD toolbox are benchmarked against ANSYS CFX results, and the two sets are compared against the experimental results. A viscous sub-layer formulation was used, with y+ ≈ 1 for the mesh. Although the focus of the present study is to investigate constant section ducts, some preliminary results for variable section ducts are also presented. Two representative cases—convergent with 1° slope (C1) and divergent with 1° slope (D1)—were selected. The Preston tube measurements are in good agreement with the numerical results and within the expected accuracy of the experimental results obtained under adverse pressure gradient conditions.

This paper examines the capability of both the Proper Orthogonal Decomposition (POD) and the Singular Value Decomposition (SVD) to identify the zones on the surface blades of a centrifugal fan that contribute the most to the sound power radiated by moving blades. The Computational Fluid Dynamics (CFD) OpenFOAM $$^{\textregistered }$$ source code is used as a first step to evaluate the pressure field at the surface of the blade moving in a subsonic regime. The fluctuating component of this pressure field makes it possible to directly estimate both the loading noise and the sound power that is radiated by the blade based on an acoustic analogy of Ffowcs Williams and Hawkings (FW&H). In the second step, the estimated loading noise is then employed to evaluate the radiated sound power using the POD and SVD approaches. It may be noted that the sound power reconstructed by the two latter approaches, when relying solely on the most important acoustic modes, is similar to the one predicted by the FW&H analogy. It is also noted that the contribution of the modes in the radiated sound power does not necessarily appear in ascending order in the decomposition (i.e., in descending order of energy). Moreover, the highest radiating SVD modes are mapped onto the blade surface so as to highlight the zones that contribute the most to the noise. It is then expected that this identification will be used as a guide in the design of the blade surface to reduce the radiated noise.

The present numerical investigation aims to study the dynamics of deflagration-to-detonation transition (DDT) in inhomogeneous and homogeneous mixtures. Modeling discontinuities, such as shocks and contact surfaces, in high-speed compressible flows require numerical schemes that can capture these features while avoiding spurious oscillations. For the numerical model, two different solution approaches, i.e., the pressure-based and density-based methods, have been adopted using the OpenFOAM® CFD toolbox. A reactive density-based solver using the Harten–Lax–van Leer-contact (HLLC) scheme has been developed within the frame of OpenFOAM®. The predictions are in reasonably good qualitative and quantitative agreement with the experiments (Boeck et al. in The GraVent DDT Database, 2015 [3]). The DDT phenomena have two major stages; flame acceleration (FA), during which the flow is in the subsonic regime, and the transition-to-detonation stage, in which the combustion wave undergoes a transition to the supersonic state. The present study indicates that it is viable to use the pressure-based algorithm for studying FA, but a density-based method is required for modeling DDT.

This chapter provides a detailed method for building an unsteady 3D CFD model with multiple embedded and adjacent rotating geometries. This is done relying solely on open-source software from the OpenFOAM $$^{\textregistered }$$ package. An emphasis is placed on interface meshing and domain decomposition for parallel solutions. The purpose of the model is the aerodynamic analysis of a quadrotor cyclogyro. The challenging features of this aircraft consist of a series of pairwise counterrotating rotors, each consisting of blades that oscillate by roughly 90 $$^\circ $$ about their own pivot point. The task is complicated by the presence of solid features in the vicinity of the rotating parts. Adequate mesh tuning is required to properly decompose the domain, which has two levels of sliding interfaces. The favored decomposition methods are either to simply divide the domain along the vertical and longitudinal axes or to manually create sets of cell faces that are designated to be held in a single processor domain. The model is validated with wind tunnel data from a past and finished project for a series of flight velocities. It agrees with the experiment in regard to the magnitude of vertical forces, but only in regard to the trend for longitudinal forces. Comparison of past wind tunnel video footage and CFD field snapshots validates the features of the flow. The model uses the laminar Euler equations and gives a nearly linear speedup on up to four processors, requiring 1 day to attain periodic stability.

Parametrisation of the geometry is one of the essential requirements in shape optimisation, and is a challenging subject when carrying out a automated procedure. It is critically important to maintain the consistency of the shape and grid quality between each evaluation, while providing flexibility for a wide range of shapes using the same parameterisation of the geometry. The sensitivity of the grid to the changes to the geometry must be at a minimum during this process. This contribution presents a review of the grid distortion and regeneration methods available within the OpenFOAM $$^{\textregistered }$$ framework which can be utilised for shape optimisation. The objective of this contribution is to compare the effectiveness of these methods in the automated procedure and to provide suggestions for improvements. Special attention is given to three major factors involving shape optimisation: automation of model abstraction, automation of grid deformation or regeneration and robustness.

The MoDeNa project [20] aims at developing, demonstrating, and assessing an easy-to-use multi-scale software framework application under an open-source licensing scheme that delivers models with feasible computational loads for process and product design of complex materials. The concept of MoDeNa is an interconnected multi-scale software framework. As an application case, we consider polyurethane (PU) foams, which are excellent examples of a large turnover product produced in a variety of qualities of which the properties are the result of designing and controlling the material structure on different scales, from the molecule to the final product. Hence, various models working at individual scales will be linked together by this framework such as meso- and macro-scale models. OpenFOAM $$^{\textregistered }$$ is deployed on the macro-scale level. A new solver (MODENAFoam) is formulated and validated to demonstrate the interconnectivity of the scales using the MoDeNa framework. The efficiency of the multi-scale model is evaluated by comparing the numerical predictions of foam density and temperature evolutions with experimental measurements. Validation results showed the capability of the framework when it is assessed for simulation of a complex system such as polyurethane foam.

Simulations are performed for a moving-bed reactor in a rotary kiln and a fluidized-bed reactor in a FINEX plant. The DEM (Discrete Element Method) and the MPPIC (Multiphase Particle-In-Cell) methods are combined with a compressible reacting flow in OpenFOAM® 2.3.x. The computational load is reduced by the DPM (Discrete Particle Method), in which a computational parcel represents a fixed number of identical particles in the DEM. The slumping and rolling modes are reproduced by adjusting particle–particle and particle–wall friction coefficients to match the regime map in Henein et al. [1]. Validation is performed in a pilot-scale rotary kiln for reduction of iron ore with heat input from LPG (Liquefied Petroleum Gas). Simulation results in a lab-scale reactor are validated against those by commercial software and experimental data for the fluidized-bed reactor. Simulation results show good agreement with actual operating data for an industrial-scale fluidized-bed reactor in the FINEX process. Reasonable trends are reproduced for the bed burners and the collective motion of particles of different diameters in the FINEX plant.

Numerical simulations of particulate fouling using highly resolved Large-Eddy Simulations (LES) are carried out for a turbulent flow through a smooth channel with a single spherical dimple or square cavity (dimple depth/cavity depth to dimple diameter/cavity side length ratio of $$t/D = 0.261$$ ) at $$\text {Re}_D = 42{,}000$$ . Therefore, a new multiphase method for the prediction of particulate fouling on structured heat transfer surfaces is introduced into OpenFOAM® and further described. The proposed method is based on a combination of the Lagrangian Particle Tracking (LPT) and Eulerian approaches. Suspended particles are simulated according to their natural behavior by means of LPT as solid particles, whereas the carrier phase is simulated using the Eulerian approach. The first numerical results obtained from LES approve the capabilities of the proposed method and reveal a superior fouling performance of the spherical dimple due to asymmetric vortex structures, compared to the square cavity.

In this chapter, I introduce, document, and verify solidificationMeltingSource: a built-in fvOption in OpenFOAM® for simulating isothermal solidification. The main challenge in simulating isothermal solidification is the incorporation of movements of the solidification front. To overcome this challenge, solidificationMeltingSource adds source terms to the momentum and energy equations. First, I rigorously derive the equations for these source terms and outline their implementation in the source code. Then, I verify solidificationMeltingSource by simulating a well-known numerical benchmark for isothermal solidification. Finally, I end the chapter by suggesting possible future extensions for solidificationMeltingSource.

In the present research, the well-known test FSI problem of wind resonance phenomenon simulation for a circular cylinder is considered. It is well-investigated, both experimentally and numerically (Chen et al. in Phys Fluids 2011, [3]), for a wide range of parameters: Reynolds number, airfoil surface roughness, incident flow turbulence, etc. In this research, the simplest case is considered, in which the roughness influence is neglected and the incident flow is assumed to be laminar. Several numerical codes, both commercial and open source, can be used for simulating airfoil oscillations in the flow. Four numerical methods and the corresponding open-source codes are considered: the finite volume method with deformable mesh in OpenFOAM $$^{\textregistered }$$ ; the particle finite element method with deformable mesh in the Kratos software; the meshfree Lagrangian vortex element method; and the LS-STAG immersed boundary method. The last two methods are implemented as in-house numerical codes. A comparison is carried out for the efficiency analysis of these methods and their implementations. It is shown that using OpenFOAM $$^{\textregistered }$$ is preferable for numerical simulations with FSI problems similar to the ones presented here, in which the investigation of system behavior within a wide range of parameters is required.

The Harmonic Balance Method for temporally periodic, non-linear, turbulent, free surface flows is presented in this work. The method transforms a periodic transient problem into a set of coupled steady-state problems, increasing the efficiency of calculation. The methodology is primarily targeted to efficient simulations related to wave–structure interaction in naval and offshore hydrodynamics. The method is validated on a 2D periodic free surface flow over a ramp test case and a 3D ship wave diffraction test case.

A novel two-way coupled Eulerian–Eulerian CFD formulation was developed to simulate drifting snow based on turbulent drag and a new viscous treatment of the drifting snow phase, derived from first principles. This approach allowed explicit resolution of the saltation layer without resorting to empiricism, unlike other Eulerian–Eulerian models based on mixture formulations and one-way coupling. Initial validations were carried out against detailed snow flux, airflow velocity, and turbulent kinetic energy measurements in a controlled experimental simulation of drifting snow in a wind tunnel using actual snow particles. The two-way coupled approach was found capable of simulating drifting snow fluxes in both saltation and suspension layers with reasonable accuracy. Recommendations were made to improve the accuracy of the method for air velocity and turbulent kinetic energy, and to allow simulating a drifting snow phase with a particle size distribution.

This chapter deals with the investigation of potentials in energy efficiency optimization for widespread agitated vessels. A lab-scale model is derived from an industrially used reactor vessel with immersed helical coils, which is utilized for several chemical basis operations. The model is analyzed with particle image velocimetry (PIV) and laser-induced fluorescence (LIF) concerning velocity and concentration fields, which gives a good validation basis for CFD analysis. However, it is challenging to validate simulations of industrial reactors. In this work, the idea is pursued of comparing the flow fields of simulations and measurements in order to validate the computational results. The simulation task implies the generation of complex geometry meshes, solving for steady-state, as well as for transient solutions, and seeking fast and effective methods. An approach to the validation of technical, large-scale simulation results is proposed through comparison of mixing times in simulations and industrial trial runs.

The aim of this work is to analyze the influence of the pressure losses of a Diffuser-Augmented Wind Turbine (DAWT) on the extractable power. Multielement diffuser geometries, generated with Salome and meshed with snappyHexMesh, are studied numerically with OpenFOAM $$^{\textregistered }$$ to find a configuration of maximum area expansion (reducing flow detachment), for different pressure losses at the actuator disk. Different geometries are studied with a $$k{-}\varepsilon $$ turbulence model. The influence of the vanes inside the diffuser has also been analyzed. The results of the present work show the importance of a careful design of the diffuser entrance.