The OpenFOAM® Journal aims at publishing works related to the OpenFOAM® computational library, with focus on the benefit for the OpenFOAM® community, is free to publish and open-access. Each publication has an associated discussion forum, to increase the interaction between the readers and the authors, and the overall impact of the contributions. The journal has a strong focus on reproducibility. Authors are required to present their results in a reproducible form, preferably by sharing codes and case setups used to generate their results, or alternatively by describing numerical settings, solver modifications, etc., in a sufficient level of detail.
OpenCFD Ltd, on behalf of the OpenFOAM Governance
Numerical Study on the Application of Overset Mesh Method for Rotating Impellers Using OpenFOAM
Intermeshing rotors exist in various applications, such as kneaders and extruders, and their performance could be assessed using computational fluid dynamics simulations. It is essential to evaluate the robustness and accuracy of such simulations. Here, we apply the overset mesh method to simulate intermeshing rotors using a Newtonian fluid to assess the suitability of the method. First, the simulations of concentric cylinders were used to evaluate the effect of three numerical approaches. Second, the simulations of a rotating impeller were applied to study five different mesh topologies. Finally, two intermeshing impellers were simulated to demonstrate the functionality of the overset mesh method, and the conservation of transported scalar was evaluated. All cases were simulated using the OpenFOAM open-source software. The general observations were: 1) The simulated velocity fields were in good accordance with the reference cases and the passive scalar was conserved in the simulation case of intermeshing impellers despite the inherent mass conservation errors. 2) However, fluctuations in power number were detected for conformal meshes in the two impeller case.
Copyright (c) 2026 Mari Niemelä, Ville Vuorinen, Mikko Kanerva, Riku Sundell, Minna Kellomäki https://creativecommons.org/licenses/by-sa/4.0
beamFoam: A Cell-Centred Finite Volume Solver for Nonlinear Geometrically-Exact Beams in OpenFOAM
This paper presents a new cell-centred finite volume beam solver, beamFoam, for simulating slender structures undergoing large deformations and rotations. The solver is based on the geometrically exact nonlinear Simo–Reissner beam theory and can represent tension, bending, shear, and torsion. Although the underlying model is 1-D, the formulation resolves 3-D kinematics, enabling accurate prediction of spatial deformations and rotations. The paper outlines the governing equations, spatial and temporal discretisation, and code implementation, together with guidelines for simulation setup. The solver’s accuracy and efficiency are demonstrated through three benchmark cases. A 3-D cantilever column under finite deformation shows close agreement with a continuum 3-D solver from the \texttt{solids4Foam} toolbox, while achieving improved accuracy on coarse meshes and significantly reduced computational cost. Additional quasi-static and dynamic tests illustrate the implementation of boundary conditions, stability of time-integration schemes, and mesh convergence behaviour. These results establish beamFoam as an efficient and accurate beam solver within OpenFOAM represent a first significant step towards fluid–structure interaction simulations of slender structures.
Copyright (c) 2025 Seevani Bali, Amirhossein Taran, Željko Tuković, Vikram Pakrashi, Philip Cardiff https://creativecommons.org/licenses/by-sa/4.0
Steady RANS Modeling of the Atmospheric Boundary Layer: A Systematic Review and Some Practical Guidelines
Accurate modeling of the neutrally stratified atmospheric boundary layer (ABL) is essential for computational wind engineering applications. The present study provides a comprehensive review of the ABL modeling approaches performed using Reynolds-averaged Navier-Stokes (RANS) equations. The main focus is on the different mechanisms used to drive the ABL flow and the corresponding boundary-condition formulations. Three major ABL modeling approaches were assessed, i.e., shear stress-driven, pressure-driven, and body force-driven flows, in terms of theoretical formulation, code implementation, and practical applications. The study addresses the role of the near-wall modeling, particularly the effects of wall functions that account for surface roughness using the aerodynamic surface roughness length and Nikuradse roughness parameter. A comparative analysis of these models is presented based on their ability to account for turbulence characteristics while maintaining the flow homogeneity. Computational simulations performed in OpenFOAM were used to assess the computational setup in these three approaches. This work generally serves as a guideline for selecting the most suitable ABL model for specific CFD applications, including urban wind studies, pollutant dispersion, and structural aerodynamics.
Neutrally-stratified atmospheric boundary layer
Copyright (c) 2026 Ivan Batistic, Mihael Cindori, Severino Krizmanić, Ivo Džijan, Franjo Juretić, Petar Škvorc, Hrvoje Kozmar https://creativecommons.org/licenses/by-sa/4.0
Implementation of the Elastic to Softening Transition and Rupture Analysis Model in OpenFOAM
The accurate modeling of viscoelastic fluids is crucial for various engineering and scientific applications, particularly in polymer processing, biological flows, and complex fluid dynamics. In this study, we implemented a new computational approach for modeling viscoelastic fluids within the OpenFOAM framework. The proposed model incorporates an improved constitutive model that captures both the elastic and dissipative properties of polymeric fluids, ensuring better accuracy in numerical simulations. The results show that ESTRA predicts polymer degradation in the interface between the principal flow and the recirculations.
Copyright (c) 2026 Eduardo Vieira, Ramon Martins, Marcio Martins, Humberto Belich, Dario Canossi https://creativecommons.org/licenses/by-sa/4.0
Particle-Resolved Simulations of Flows Through Sphere, Cylinder or Spherocylinder Assemblies: Automatic Workflow
We developed an OpenFOAM® application for generation of tri-periodic assemblies of fixed non-overlapping particles, intended for direct numerical simulations with body-fitted unstructured meshes. The particles can be spherical, cylindrical or spherocylindrical, with random or pre-assigned positions and orientations, and mono- or polydisperse. The assemblies are optimized for meshing with snappyHexMesh: various meshing errors are minimized by using automatically generated edge meshes, as well as by controlling the interparticle distance and tangentiality to the boundaries. Further, we provide a new pressure boundary condition which improves the accuracy of the resulting hydrodynamic forces. The available post-processing function objects are extended to also calculate stresslets (i.e., resistance to the straining motion), relevant for rheology of suspensions. The workflow is validated against available analytical and numerical data, showing excellent agreement. With our present contribution, an OpenFOAM® user is able to significantly reduce the pre-processing efforts: typically, packings of solid fractions up to 0.3 are generated in the range of a few seconds to around a minute. This allows for efficient gathering of data needed for formulation of closure laws or for developing machine learning models, relevant for industrial applications such as pneumatic conveying and fluidized beds.
Copyright (c) 2025 Jelena Macak, Nicolas Fintzi, Lionel Gamet, Jean-Lou Pierson, Mathieu Morin https://creativecommons.org/licenses/by-sa/4.0
Title: Hydraulic design of natural flows for enhanced biodiversity using OpenFOAM Author: Eric Lillberg Vattenfall AB, Research & Development SE-169 92 Stockholm, Sweden Visit: Evenemangsgatan 13 https://orcid.org/0009-0004-8256-7517
Copyright (c) 2025 Eric Lillberg https://creativecommons.org/licenses/by-sa/4.0
Prediction of Crossflow Transition using γ Transition Model Coupled with Reynolds Stress Transport Turbulence Model
This study presents an enhanced second-order closure transition model, SSG/LRR-ω-γ, incorporating crossflow transition effects for improved prediction of laminar–turbulent transition in three-dimensional boundary layers. The original formulation couples the SSG/LRR-ω Reynolds stress model with Menter’s one-equation γ transition model to address streamwise instabilities. To extend its capabilities, a local helicity-based criterion is introduced to account for crossflow-induced transition. The modified model is assessed using two benchmark configurations: the NLF(2)-0415 infinite swept wing and the DLR 6:1 prolate spheroid, across a range of operating conditions. A grid sensitivity analysis is also performed to ensure numerical robustness. Results demonstrate that the crossflow model accurately captures crossflow-induced transition and provides improved agreement with experimental data compared to the original streamwise-only formulation.
Copyright (c) 2025 Naina Pisharoti, Stefano Brizzolara https://creativecommons.org/licenses/by-sa/4.0
3D Solver for Viscous Fluids to Simulate Lava Flows
In this work, we present a new OpenFOAM solver, called interThermalRadConvFoam, to simulate free-surface viscous fluids with temperature changes due to radiative, convective, and conductive heat exchanges. The solver is based on interFoam (available in OpenFOAM) and thus on the Volume of Fluid technique used to describe the multiphase dynamics of two incompressible, viscous, and immiscible fluids (based on the Interface Capturing strategy). In our model, the two fluids are the fluid of interest with high viscosity and the surrounding atmosphere. Being interested in temperature effects, we added to the mass and momentum equations from interFoam an equation for energy that models the thermal exchanges between the fluid and the environment. Furthermore, a temperature-dependent viscoplastic model is used for the final application to lava flows. Here we present some results of numerical tests performed with interThermalRadConvFoam for a benchmark from literature based on a laboratory experiment and an application to a real lava flow by simulating the Pico do Fogo 2014–2015 Eruption. For the simulation of the laboratory experiment, we also present simulations executed using a dynamic mesh with adaptive refinement.
Temperature-dependent non Arrhenian Newtonian viscosity
Copyright (c) 2025 Elisa Biagioli, Mattia de' Michieli Vitturi, Fabio Di Benedetto, Margherita Polacci https://creativecommons.org/licenses/by-sa/4.0
Large-Eddy Simulation of Turbulent Channel Flow with OpenFOAM
This article presents the results of large-eddy simulations (LES) of fully developed turbulent channel flow at Reτ ≈ 1000 using OpenFOAM solvers. The purpose of the work is two-fold. One is to provide publicly available validation results for an important LES benchmark, together with the case setup and codes used for post-processing. The second is to serve as an entry point for those starting out with scale-resolving simulations of turbulence with OpenFOAM. To that end, the exposition of the material is somewhat lengthier and more pedagogical than in a typical scientific paper. The simulations cover a range of grid resolutions to demonstrate the sensitivity of the predictive accuracy to the cell size. Furthermore, the results from the implicit LES are compared with those obtained using the Sigma subgrid-scale model. The post-processing aims to cover most quantities typically considered in the analysis of a turbulent flow, including velocity statistics up to fourth order, fluctuations of vorticity, spatial spectra and two-point correlations, linear spectral coherence, and the budget of the turbulent kinetic energy. To facilitate the analysis, we draw on both built-in OpenFOAM capabilities and community contributions. The results show that upon sufficient resolution of the inner scales, OpenFOAM accurately simulates wall-bounded turbulence, showing excellent agreement with reference data from direct numerical simulations. However, explicit subgrid scale modelling fails to improve the simulations’ accuracy.
Copyright (c) 2026 Timofey Mukha, Matteo Parsani https://creativecommons.org/licenses/by-sa/4.0
Testing Strategies for OpenFOAM Projects
While testing is increasingly recognized as essential in scientific software development, it is not yet standard practice within the OpenFOAM community for developing new solvers and features. This gap stems partly from the challenges of integrating testing into typical OpenFOAM workflows and limited guidance on implementing effective tests. Writing tests for complex software like OpenFOAM based projects presents unique obstacles, including difficulty in configuring tests for various cases. This paper addresses these issues by discussing established test types in the context of OpenFOAM, identifying common challenges in developing tests for this platform, and suggesting best practices to enhance the testability of code based on OpenFOAM. Detailed guidance is provided for integrating the Catch2 unit test framework, alongside two new tools: the foamUT framework and the OpenFOAM Benchmark Runner (OBR), which facilitate unit and integration testing. To illustrate these tools in practice, we present three case studies. The first demonstrates the direct integration of Catch2 in the WENOExt project, showcasing test case creation and its synergy with OpenFOAM projects. The second introduces the foamUT framework, which simplifies Catch2 integration for OpenFOAM projects. Finally, the OBR framework is used for benchmarking and integration tests in the OpenFOAM Ginkgo layer. Additionally, we discuss the current state of testing in OpenFOAM and emphasize the need for more comprehensive testing practices within this community, particularly with libraries such as Catch2. Overall, this paper serves as a practical introduction to unit and integration testing for OpenFOAM developers and introduces new tools that lower the barrier to entry, improve test suite robustness, and simplify unit test integration.
Copyright (c) 2025 Jan Wilhelm Gärtner, Gregor Olenik, Mohammed Elwardi Fadeli, Lukas Petermann, Andreas Kronenburg, Holger Marschall, Hartwig Anzt https://creativecommons.org/licenses/by-sa/4.0
Title: Sensitivity Analysis of an Unsteady Flow Around a Pitching Airfoil
Copyright (c) 2023 Julien Reveillon https://creativecommons.org/licenses/by-sa/4.0
Development of an OpenFOAM Solver to Investigate the Dynamic Absorption and Desorption Processes in Metal-hydrides
The purpose of this paper is to introduce twoRegionHydrideFoam, a newly developed solver that enables the calculation of hydrogen absorption and desorption reactions in metal-hydrides. This solver integrates simulations of chemical, thermodynamic, and continuum mechanical processes. The primary focus is to provide a detailed, locally resolved description of hydrogen loading cycles under varying temperatures and pressures. We discuss the mathematical model assembled for this purpose and its implementation in OpenFOAM. Additionally, precise heat transfer calculations are achieved using the groovyBC third-party library. The performance and accuracy of the solver are demonstrated through a parametric study where key system parameters are systematically varied and analyzed. Furthermore, this paper includes preconfigured example cases to facilitate understanding and application of the solver. This solver meets the increasing demand for advanced tools in sustainable energy storage and hydrogen technology research. By expanding the capabilities of OpenFOAM®, it offers a powerful platform for researchers and engineers to explore and develop innovative solutions within the hydrogen economy.
Copyright (c) 2025 Christoph Ulrich, Maximilian Richard Ziegler, Daniel Felix Szambien, Christian Buhl, Roland Scharf https://creativecommons.org/licenses/by-sa/4.0
Analysis of Coupling Strategies for Conjugate Heat Transfer Problems
Numerical solutions to conjugate heat transfer (CHT) problems present challenges regarding accuracy, stability, and computational cost. The current study presents a detailed analysis of the existing OpenFOAM® CHT solvers, including commentary on the multiple forms of the available governing equations and coupling methods. Subsequently, two modified CHT approaches are proposed: (i) a new partitioned algorithm with improved efficiency, and (ii) the available monolithic CHT solver in foam-extend-4.0 was modified and extended to multiple regions. The performance of the proposed solvers is assessed on several transient test cases with various degrees of coupling strength. The results reveal the superiority of the proposed monolithic approach over the partitioned ones, particularly for problems for more than two regions. It is also found that the new partitioned approach is computationally more efficient than the available partitioned solvers.
Copyright (c) 2025 Emad Tandis, Philip Cardiff, Ali Ashrafizadeh https://creativecommons.org/licenses/by-sa/4.0
lcs4Foam – An OpenFOAM Function Object to Compute Lagrangian Coherent Structures
To facilitate the understanding and to quantitatively assess the material transport in fluids, a modern characterisation method has emerged in fluid dynamics in the last decades that is based on dynamical systems theory. It allows to examine the most influential material lines which are called Lagrangian Coherent Structures (LCS) and order the material transport into dynamically distinct regions at large scales which resist diffusion or mixing. LCS reveal the robust skeleton of material surfaces and are essential to assess material transport in time-dependent flows quantitatively. Candidates of LCS can be estimated and visualised from finite-time stretching and folding fields by calculating the Finite-Time Lyapunov Exponents (FTLE). In this contribution, we provide a function object to compute FTLE during CFD simulation by coupling OpenFOAM to the third-party library libcfd2lcs. This enables the OpenFOAM community to assess the geometry of the material transport in any flow quantitatively on-the-fly using virtually any OpenFOAM flow solver.
Copyright (c) 2024 Constantin Habes, Alexandra von Kameke, Mohammed Elwardi Fadeli, Holger Marschall https://creativecommons.org/licenses/by-sa/4.0
Modelling Thermo-Electrohydrodynamic Convection in Rotating Spherical Shell Using OpenFOAM®
Convection in rotating spherical shells can be considered a simplified analogue of many geophysical and astrophysical flows. Here, we investigate a direct numerical simulation of a dielectric fluid in an electric central force field inducing thermo-electrohydrodynamic (TEHD) convection with numerical methods to obtain an accurate solution of the transport equations describing rotating TEHD convection in a non-isothermally heated spherical shell. The choice of the numerical model is based on the International Space Station Experiment GeoFlow and its successor, AtmoFlow. The numerical methods consist of a custom-developed finite volume solver based on the OpenFOAM ecosystem that is not limited to any geometric restrictions, a commercially developed finite element method, and a pseudo-spectral method. This study aims to validate a custom-coded finite volume solver for investigating TEHD convection for a parametric study of the AtmoFlow spherical shell experiment. The developed TEHD finite volume solver showed solution errors of 1% or less compared to the other two implemented numerical methods.
Copyright (c) 2025 Yann Gaillard, Peter S.B. Szabo, Vadim Travnikov, Christoph Egbers https://creativecommons.org/licenses/by-sa/4.0
Implementation of a Lag Elliptic-Blending model for RANS equations in OpenFOAM
Turbulence modeling remains a significant challenge in Computational Fluid Dynamics. Achieving a balance between model accuracy and computational efficiency often leads to the widespread utilization of RANS (Reynolds Averaged Navier Stokes) turbulence models. The current study focuses on implementing the k−ε Lag Elliptic Blending turbulence model within OpenFOAM®. This extension of the conventional k−ε model introduces an elliptic equation to handle non-uniform behavior near walls and a transport equation to account for the lag between stress and strain tensors. Comparison of results from two benchmark cases with those obtained from the commercial software STAR-CCM+®, which also includes the model, reveals good agreement between the two codes. Consequently, the implementation can be considered verified.
Copyright (c) 2024 Eleonora Gajetti, Luca Marocco, Gianluca Boccardo, Antonio Buffo, Laura Savoldi https://creativecommons.org/licenses/by-sa/4.0
Title: Vortical flow structures in the Timisoara Swirl Generator Author: Saeed Salehi Fluid Dynamics Division Mechanics and Maritime Sciences Department Chalmers University of Technology SE-412 96 Gothenburg, Sweden saeed.salehi@chalmers.se
Copyright (c) 2024 Saeed Salehi https://creativecommons.org/licenses/by-sa/4.0
Implementing moving object capability in a two-phase Eulerian model for sediment transport applications
This article presents the validation of a modified 6DoF solver which includes the contribution of particle forces on rigid objects. The solver is an extension of sedFoam, employed for a wide range of sediment transport applications. The first validation consists in a simple case of a sphere freely falling in a pure fluid. Then, the same sphere is submerged in a fluid with suspended particles. The next step involves placing a granular bed under the sphere to study its arrest due to particle-particle interactions. Lastly, the trajectory of a cylinder immersed in a uniform granular flow is studied to emphasize the lift and drag forces exerted by the particle phase on the solid object. Results show that overSedDyMFoam accurately reproduces experimental/numerical measurements successfully capturing the behavior of solid objects subjected to granular and fluid forces. This implementation is a significant step towards understanding complex interactions between fluid, particles, and structures.
Copyright (c) 2024 Eduard Puig Montella, Cyrille Bonamy, Julien Chauchat, Tian-Jian Hsu https://creativecommons.org/licenses/by-sa/4.0
Implementation of a VoF solver with phase change for the simulation of internal cavitation and droplet breakup in injectors
This study presents the implementation and derivation of a Volume of Fluid (VoF) solver capable of taking into account pressure driven phase change and handle three fluids. The implemented code is designed to investigate internal nozzle cavitation and subsequent injection and jet breakup. An extended cavitation model is also implemented that can handle phase change in the presence of a third phase. Detailed description and derivation of the mathematical system is presented. The solver is validated on a one-dimensional benchmark case from the literature and verified on an experimentally well-documented geometry. The verification shows the developing cavitation regime is well captured by comparing velocity profiles and flow images with experimental measurements and visualisation.
Copyright (c) 2024 Bjørn Christian Dueholm, Jesper de Claville Christiansen, Benny Endelt, Nikolaj Kristensen, Jakob Hærvig https://creativecommons.org/licenses/by-sa/4.0
An Open-Source Framework for Modeling the Evolution of Fiber Orientation
Modeling fiber orientation plays a crucial rule in predicting the behaviour of fiber reinforced thermoplastic materials. The equation that governs the evolution of the fiber orientation is hyperbolic in nature and requires handling fourth-order tensors, which are currently unavailable in OpenFOAM® . The current work explores the possibility of using OpenFOAM® and symbolic computation for modeling the evolution of fiber orientation. For this purpose, a functionObject was programmed to work as a plug-in solver for any OpenFOAM® incompressible flow solver, with the ability to compute the evolution of the second-order orientation tensor in a decoupled manner. Several fiber orientation models and closure relations available in the literature were implemented in the tool, which were verified by comparing their predictions with independent results obtained by numerically integrating the associated governing equations.
Copyright (c) 2025 Bruno Ramoa, Ricardo Costa, Francisco Chinesta, João Miguel Nóbrega https://creativecommons.org/licenses/by-sa/4.0
Comparison of CFD-DEM and MP-PIC in the Simulation of Metal Powder Conveying for Laser Metal Deposition
Pneumatic conveying of fine powders is essential for many industrial processes, including Laser Metal Deposition (LMD), a Direct Metal Additive Manufacturing (DMAM) technology that builds solid objects layer-by-layer using a laser to melt metal powder. To optimize the process, it is necessary to have a correct understanding of the powder’s behaviour under the process condition. The coupled Computational Fluid Dynamics - Discrete Element Modelling (CFD-DEM) and MultiPhase - Particle In Cell (MP-PIC) are two popular Eulerian-Lagrangian models to simulate particle laden flows. This study compares them to analyse powder behaviour in a small channel of LMD machines. Results from the two methods differ significantly, with CFD-DEM offering a more accurate representation of the physical reality, while MP-PIC is more computationally efficient. The study finds that the CFD-DEM method produces higher fluctuations in the solids flow rate due to the formation of particle clusters, while MP-PIC displays a smooth and essentially uniform flow. The results suggest that CFD-DEM should be used for more accurate and detailed studies of solids flow rate in pneumatic conveying systems, while MP-PIC can be used for preliminary studies and design optimization.
Copyright (c) 2024 Lorenzo Pedrolli, Beatriz Achiaga Menor, Inger Martinez de Arenaza, Alejandro López https://creativecommons.org/licenses/by-sa/4.0
Validation of High Speed Reactive Flow Solver in OpenFOAM with Detailed Chemistry
An OpenFOAM® based hybrid-central solver called reactingPimpleCentralFoam is validated to compute hydrogen-based detonations. This solver is a pressure-based semi-implicit compressible flow solver based on central-upwind schemes of Kurganov and Tadmor. This solver possesses the features of standard OpenFOAM® solvers namely, rhoCentralFoam, reactingFoam and pimpleFoam. The solver utilizes Kurganov & Tadmor schemes for flux splitting to solve the high-speed compressible regimes with/without hydrodynamic discontinuity. In this work, we present the validation results that were obtained from one-dimensional (1D) and two-dimensional (2D) simulations with detailed chemistry. We consider three different mixtures that fall into the categories of weakly unstable mixture (2H2 +O2 +3.76Ar and 2H2 +O2 +10Ar), and moderately unstable mixture (2H2 +O2 +3.76N2), based on their approximate effective activation energy. We performed the numerical simulations in both laboratory frame of reference (LFR) and shock-attached frame of reference (SFR) for the 1D cases. The 1D simulation results obtained using this solver agree well with the steady-state calculations of Zel’dovich von Neumann Döring (ZND) simulations with an average error below 1% in all cases. For the 2D simulations, circular hot-spots were used to perturb the initially-planar detonations to develop into spatio-temporally unstable detonation front. The convergence is declared when the front does not deviate much from the CJ speed (Chapman-Jouguet) and the regularity of cellular pattern on the numerical smoke foils reaches a steady state. We have verified from our preliminary studies that the SFR-based simulations are computationally cheaper in comparison to the LFR simulations and that the required grid resolution is always lesser in the former than the latter to reach the same level of accuracy (in terms of speed of the detonation front and cell sizes from the numerical smoke foil). We have also verified that at least 24 points per induction zone length (for weakly unstable mixture) and 40 points per induction zone length (for moderately unstable mixture) are required to sufficiently resolve the detonation structures that are independent of grids, boundary and initial conditions. Further reduction in computational cost of approximately 50% is achieved by using non-uniform grids, which converge effectively to the same solutions in comparison to the results from twice the number of grids with uniform resolution.
Copyright (c) 2024 Vigneshwaran Sankar, Karl P. Chatelain, Josué Melguizo-Gavilanes, Deanna A. Lacoste https://creativecommons.org/licenses/by-sa/4.0
A Modified Overset Method in OpenFOAM for Simultaneous Motion and Deformation: A Case Study of a Flexible Flapping Foil
The influence of wing deformation in animal propulsion and motion is an intriguing phenomenon that has contributed to a growing interest in biomimetics in both academia and industry. The study focuses on developing a robust numerical tool for analyzing the motion of biological systems in fluid flows, crucial to understanding fluid-structure interaction (FSI) phenomena. The research introduces a new mesh deformation solver, dynamicOversetZoneFvMesh, designed to address limitations in OpenFOAM's conventional Overset method. This solver enables the application of both rigid body motion and deformation at specified patches within certain zones, allowing for more complex motion scenarios. Through meticulous verification, parallelization, validation, and mesh convergence studies, the modified Overset solver's reliability is confirmed. Two cases are examined: a rigid-body flapping foil and a flexible foil with leading-edge deformation. Results demonstrate the adapted solver's proficiency in managing complex fluid dynamics and accommodating simultaneous motion and deformation. Furthermore, the study reveals that leading-edge flexibility improves the power extraction efficiency of flapping foils, aligning with previous literature. Overall, the research lays the foundation for advancing FSI simulations and opens avenues for addressing previously challenging problems in the field.
Copyright (c) 2024 Karim Ahmed, Ahmed A. Hamada, Ludovic Chatellier, Mirjam Furth https://creativecommons.org/licenses/by-sa/4.0
A Cyclic Heat Transfer Solver for OpenFOAM
Channels with periodically repeating geometries are often simulated using periodic or cyclic boundary conditions. By calculating the temperature and flow field in one periodic module, the resulting distributions can be generalized to multiple modules. This reduces the computational load by simulating a single module versus the whole structure. This is a particularly useful approach when performing large optimisation studies of periodic geometries, such as compact heat exchangers. Currently, OpenFOAM only supports cyclic boundary conditions for pressure and momentum, but not heat transfer. The present work introduces a steady and an unsteady solver for cyclic heat transfer with constant wall temperature boundary conditions. The solver is validated against analytical Hagen-Poiseuille flow and two configurations of periodic wavy channels. In the latter case, the results are compared to existing literature.
Copyright (c) 2023 Michael Coe, Daniel Holland https://creativecommons.org/licenses/by-sa/4.0
Verification and Validation of the Spalart Allmaras Model with Rotation and Curvature Correction for Incompressible and Compressbile Flows
The Spalart-Allmaras turbulence model is the model which gets the highest technological readiness level in the NASA turbulence model resource home page. The model is widely used to predict external incompressible and compressbile flows. Different corrections to this model incorporating additional physical effects are presented on the same home page. Unfortunately none of these corrections are available in the official OpenFOAM version. Furthermore, no publicly available repository which contains the full set of corrections suggested by Shur et al. [1] to account for curvature and rotation effects was found. In this technical note, the rotation and streamline curvature correction is incorporated into the Spalart-Allmaras model in order to overcome this limitation. The same equations as suggested in Shur et al. [1] are implemented and verified by means of the incompressible flow in a rotating channel, a 2D bump flow in a channel and a channel flow exhibiting a U-turn. Regarding the rotating channel flow and the flow in a U-turn some quantitative differences remain with respect to the results of Shur et al. [1]. For the rotating channel flow, a careful consistency check with respect to the analytical relations leading to the computation of the factor multiplied with the production term was made. No inconsistencies in the implementation where found. Unfortunately the exact reason for the differences between the present results compared to the computations of Shur et al. [1], was not found. The interested readers are encouraged to help to clarify these issues. In the fourth test case it is shown that the model predicts a more correct turbulent viscosity distribution in the transonic flow around a delta wing. Applying the streamline and curvature corrections to the Spalart-Allmaras model predicts an earlier vortex breakdown compared to the standard Spalart-Allmaras model for a high angle of attack configuration. The agreement with the reference experiments is much better when using the corrections proposed by Shur et al. [1] to the Spalart-Allmaras compared to the standard Splart-Allmaras model.
Copyright (c) 2023 Michael Alletto https://creativecommons.org/licenses/by-sa/4.0
TwoPhaseFlow: A Framework for Developing Two Phase Flow Solvers in OpenFOAM
We present a new OpenFOAM based open-source framework, TwoPhaseFlow, enabling fast implementation and testing of new phase change and surface tension force models for two-phase flows including interfacial heat and mass transfer. Capitalizing on the runtime-selection mechanism in OpenFOAM, the new models can easily be selected and benchmarked against analytical solutions and existing models. The framework currently includes the following three interface curvature calculation methods for surface tension: 1) the height function method, 2) the parabolic fit method and 3) the reconstructed distance function method. As for phase change, two models are available: 1) Interface heat resistance and 2) direct heat flux. These can be combined in three solvers: 1) InterFlow for isothermal, incompressible two-phase flow, 2) compressibleInterFlow for compressible, non-isothermal two-phase flow and 3) multiRegionPhaseChangeFlow for compressible, non-isothermal two-phase flow with conjugated heat transfer. By design, addition of new models and solvers is straightforward and users are encouraged to contribute their specific models, solvers, and validation cases to the library.
Copyright (c) 2023 Henning Scheufler, Johan Roenby https://creativecommons.org/licenses/by-sa/4.0
IKA-FLOW : A Flexible Body Overset Mesh Implementation for Fish Swimming
Simulation of inertial aquatic swimmers requires fluid structure interactions with temporal body geometry deformation. In practice, his results in a change of the computational domain boundaries that represent the ”swimmer.” These simulations are traditionally done sing body-fitted mesh and mesh morphing methods, but have drawbacks of negative cell volumes and small time-steps to account for the complex swimming motion. In contrast, the overset mesh method, also provided by OpenFOAM®, overcomes most of the drawbacks of the mesh morphing method at the expense of interpolation error. The current OpenFOAM® overset motion library only supports rigid body motion and cannot be used to resolve a body undergoing undulation. A modified motion solver is presented that allows for the complex mesh motion of an overset mesh for four body-caudal fin (BCF) virtual swimmers. The results of this solver are compared with published data of body-fitted meshes. The effect of different simulation parameters (including number of solving iterations, time delay, and temporal resolution) is investigated. Additionally, a novel simulation and comparison of the Ostraciiform locomotion mode with Anguilliform, Carangiform, and Thunniform modes are made investigating the wake, drag and lift. It is concluded that fish undulation has a marked effect on reducing lift generation. Lastly, a comparison of turbulence models (Spalart-Allmaras, k − ω SST, and k − kL − ω) at multiple Reynolds numbers shows that all three models have similar performance at lower Reynolds numbers but diverge at higher numbers.
Copyright (c) 2023 Michael Coe, Stefanie https://creativecommons.org/licenses/by-sa/4.0
Modular Framework for the Solution of Boundary-coupled Multiphysics Problems
This paper presents a modular multiphysics framework developed for OpenFOAM. The framework is built around an iterative implicit coupling scheme based on a multi-region partitioned approach. This scheme allows the implementation of formal implicit time-marching schemes, which improves the stability of strongly interacting coupled problems. This methodology allows physical interactions to be handled through specifically designed interface boundary conditions. It also allows region-specific solvers to be implemented as modular class solvers. The coupling methodology is handled with a main program that manages solver-specific actions. The aim of this framework is to facilitate the implementation and testing of new multiphysics coupling problems in an integrated code structure. To show the capabilities of the framework to integrate new physics, solvers and boundary conditions requirements are discussed. Also, three validated examples involving fluid-structure interactions, conjugate heat transfer, and fluid-structure-thermal interactions are presented. Although all these problems are boundary-coupled multiphysics problems, the framework is conceptually not limited to this kind of problems. The benefit of this work to the OpenFOAM community is a general and modular framework that facilitates the setup and solution of diversified multiphysics problems, and that illustrates the implementation of modular interface boundary conditions between physics regions.
Copyright (c) 2023 Gabriel St-Onge, Mathieu Olivier https://creativecommons.org/licenses/by-sa/4.0
Title: Instantaneous isosurfaces of Q criterion for a Detached Eddy Simulation around buildings in Vauxhall, London Author: Joshua Millar WSP in the UK WSP House 70 Chancery Lane London WC2A 1AF Joshua.millar@wsp.com, https://wsp.com
Copyright (c) 2023 Joshua Millar https://creativecommons.org/licenses/by-sa/4.0
Sensitivity Analysis of an Unsteady Flow Around a Pitching Airfoil
Various ways to control the loads and thus the output of the wind turbine by pitching the blades and by controlling the rotational speed already exist. However, adverse pressure gradient leading to flow separation at the trailing edge, with relatively high angles of attack (AOA) due to blade-pitching motion, largely affects the airfoil aerodynamic performance. This work presents the results of a numerical study of the unsteady flow around a pitching FFA-W3-301 airfoil at a Reynolds 1.6 × 106 using OpenFOAM®, as obtained by first performing 2D Unsteady Reynolds-Averaged Navier- Stokes (URANS) simulations whereby the flow characteristics are simulated by the shear stress transport (SST) k − ω model and Spalart-Allmaras (SA). The influence of various parameters on the numerical results is investigated, namely y+, computational grid resolution, dynamic mesh technique, time step and turbulence model. Integral aerodynamic forces and detailed flow patterns are compared with experimental measurements presented in the literature. A range of angles of attack, including early stalls, are examined. For best-performing parameters, an adequate refinement close to the wall was imperative in order to match experiments, especially during the upstroke motion of the airfoil, while for the downstroke phase, some differences still appeared. The agreement was greatly improved by using a 2.5D hybrid RANS-LES approach with enhanced delayed-Detached Eddy Simulation (DES) capabilities.
Copyright (c) 2023 Javier Añez, Hakim Hamdani, Julien Reveillon, Benjamin Duret, Francois-Xavier Demoulin https://creativecommons.org/licenses/by-sa/4.0