OpenFOAM News from CFD Direct

CFD Direct is delighted to announce Principles of CFD, their new CFD Training course with OpenFOAM.  The course was created by Chris Greenshields and Aidan Wimshurst. It draws on the experience of Chris’s 16 years of OpenFOAM training, involving 800+ days with over 3500 participants. Aidan brings further experience from his Fluid Mechanics 101 channel on YouTube and the ensuing interaction with subscribers.  The course aims to fill the knowledge gap in CFD and improve CFD practice using a procedure of preparatory, diagnostic and objective calculations.  The course is 4 days duration and is delivered in person with initial dates of 16-19 September 2024, Cologne, Germany and 28-31 October 2024, Chicago, USA.

Anyone investing in OpenFOAM Training must want training that delivers the best return on their investment. It can be difficult to choose the best OpenFOAM training from the variety of disparate training offerings in a market that is particularly open due to the open source nature of the software. Questions should be asked of potential training providers to establish their credibility and experience in OpenFOAM and in CFD training. In this article we present 10 questions that might usefully be asked and present CFD Direct’s answers to the questions.

In Year 9 of CFD Direct, we built on the success modular solvers and non-conformal coupling in OpenFOAM. We replaced liquid film functionality and improved dynamic mesh, including mesh-to-mesh mapping, decomposition and redistribution, to the point that OpenFOAM can simulate internal combustion engines including piston and value motion. We managed the OpenFOAM Foundation, releasing OpenFOAM v11, packaging OpenFOAM-dev and publishing websites and documentation. We provided training and cloud services to OpenFOAM users, and began creating a new course “Principles of CFD.”

In Spring/Summer 2024, CFD Direct is running its OpenFOAM Training courses — Essential CFD, Applied CFD and Programming CFD — fully updated with the latest features of the new version 11 release of OpenFOAM. The training uses new features in OpenFOAM v11 for more productive and effective CFD. All courses are delivered as live virtual training. Essential and Applied CFD courses are available: 29 Jan-2 Feb, 4-8 Mar, 8-12 Apr, 13-17 May. Programming CFD is available 12-14 Feb, 18-20 Mar, 3-5 Jun, 24-26 Jun.

In 2016 we published a guide for Productive CFD with OpenFOAM with tools we first released in OpenFOAM v4. The tools included the post-processing CLI and template cases, and applications such as foamDictionary. We extended the article following the release of new tools such as TAB completion in OpenFOAM v5 and again later with the introduction of new tools in subsequent versions of OpenFOAM. This article describe more significant new tools introduced in OpenFOAM version 11, notably foamToC and foamPostProcess, to provide compatibility with its modular solvers, while maintaining backward-compatibility with application solvers.

The OpenFOAM User Guide provides an introduction to OpenFOAM, through some basic tutorials, and some details about the general operation of OpenFOAM. OpenFOAM is a collection of approximately 250 applications built upon a collection of over 100 software libraries (modules). Each application performs a specific task, e.g the snappyHexMesh application can generate meshes for complex geometry, such as a vehicle. The simpleFoam application could then be used to simulate steady-state, turbulent, incompressible flow around the vehicle…

In Year 8 of CFD Direct, we made some very significant developments to OpenFOAM, including non-conformal coupling, modular solvers and redesign of the dynamic mesh functionality. We managed the OpenFOAM Foundation, releasing OpenFOAM v10, packaging OpenFOAM-dev and publishing websites and documentation. We provided 63 days of OpenFOAM Training to users around the world, supported by the release of our book, “Notes on Computational Fluid Dynamics: General Principles”. We released Web CFD Direct From the Cloud (CFDDFC®), providing OpenFOAM which can be accessed from a remote desktop running in a web browser.

In August 2022, CFD Direct introduced modular solvers to the OpenFOAM development version. Modular solvers are written as classes, in contrast to the traditional application solvers which have been integral to OpenFOAM since icoFoam in 1993.  They are simpler to use, maintain and understand than application solvers. They are more flexible; in particular, modules for different fluids and solids can be coupled across multiple regions, e.g. for conjugate heat transfer (CHT) with multiphase flow.  Modular solvers are deployed using the foamRun or foamMultiRun applications, which contain a generic solution algorithm for single and multiple regions, respectively. Additional modules and applications replace existing tools for data processing and case configuration.

OpenFOAM is the leading free, open source software for computational fluid dynamics (CFD), distributed by The OpenFOAM Foundation. In 2014, OpenFOAM had accumulated significant “technical debt” due to a drive for new functionality at the expense of maintenance. Facing an unsustainable level of technical debt, CFD Direct was founded to manage and develop OpenFOAM back to a sustainable position. Code repair has targeted niche functionality that receives less testing. Redesign of larger, critical components of OpenFOAM has eliminated clusters of issues. By 2022, CFD Direct has recovered most of the technical debt, making OpenFOAM significantly more robust, usable and extensible.

CFD Direct is pleased to announce the release of version 10 of CFD Direct From the Cloud™ (CFDDFC®), available on Amazon Web Services (AWS) Marketplace as the standard CFDDFC product and CFDDFC (Arm). Standard CFDDFC v10 includes OpenFOAM v10, ParaView v5.6.0, OpenMPI v4.1.1 and FreeCAD v0.19.2, running on Ubuntu 20.04 LTS. CFDDFC (Arm) is server-only including OpenFOAM v10 and OpenMPI v4.1.1, running on Ubuntu 20.04 LTS. CFDDFC runs on single instances with up to 64 C6i Intel cores (c6i.32xlarge), 96 C6a AMD cores (c6a.48xlarge) or 64 C7g Graviton cores (c7g.16xlarge) and in clusters with with good parallel scaling on clusters of instances up to 1000 cores.

In May 2022, CFD Direct released Non-Conformal Coupling (NCC) in OpenFOAM to connect regions of a domain with independent meshes for applications including rotating geometry. NCC is a robust replacement for the Arbitrary Mesh Interface (AMI) and associated ACMI and Repeat AMI functionalities. Unlike the AMI functionalities, NCC ensures conservation which is essential for accuracy but also for stability, in particular in numerical schemes designed to maintain boundedness, e.g. in multiphase flows. NCC naturally works for partially-overlapping geometries, as illustrated by the case of opening and closing of a three port ball value.

In Year 7 of CFD Direct, our developments of OpenFOAM included a generalised load balancer for parallel running . We provided core maintenance, including standardisation of fluid properties, and repaired issues, e.g. to stablise multiphase simulations. We managed the OpenFOAM Foundation, releasing OpenFOAM v9, packaging OpenFOAM-dev and publishing websites and documentation. We produced our book , “Notes on Computational Fluid Dynamics: General Principles”, delivered 56 days of Live Virtual OpenFOAM Training, and provided cloud CFD with CFDDFC® to over 1000 subscribers.

In Spring/Summer 2022, CFD Direct is running its OpenFOAM Training courses — Essential CFD, Applied CFD and Programming CFD — fully updated with the latest features of the new version 9 release of OpenFOAM. The training uses new features in OpenFOAM v9 for more productive and effective CFD. All courses are delivered as live virtual training. Essential and Applied CFD courses are available: 7-11 Feb, 14-18 Mar, 9-13 May, 6-10 Jun. Programming CFD is available 25-27 Jan, 22-24 Feb, 29-31 Mar, 23-25 May, 21-23 Jun.

CFD Direct is pleased to announce the release of version 9 of CFD Direct From the Cloud™ (CFDDFC®), available on Amazon Web Services (AWS) Marketplace as the standard CFDDFC product and CFDDFC (Arm). Standard CFDDFC v9 includes OpenFOAM v9, ParaView v5.6.0, OpenMPI v4.1.1 and FreeCAD v0.19.2, running on Ubuntu 20.04 LTS. CFDDFC (Arm) is server-only including OpenFOAM v9 and OpenMPI v4.1.1, running on Ubuntu 20.04 LTS. CFDDFC runs on single instances with up to 48 C5 Intel cores (c5.24xlarge) or 64 C6 Arm-based cores (c6g.16xlarge) and in clusters with with good parallel scaling on clusters of instances up to 1000 cores.

In March 2021, CFD Direct replaced fvOptions with new fvModels and fvConstraints classes. fvModels provided a more complete framework for implementation of complex models which could be optionally selected during a simulation. New fvModels were implemented for heat transfer and sources, which are easier to configure than a general fvOption. Pressure limiting was implemented as an fvConstraint named limitPressure, consistent with limitVelocity and limitTemperature. With additional fvModels such as cloud and surfaceFilm, solvers such as reactingFoam replicate the functionality of several existing solvers which are deprecated.

In Year 6 of CFD Direct, our developments of OpenFOAM included new interface capturing methods and multicomponent transport models. We provided core maintenance, including redesign of fvOptions and transport modelling, and repaired issues, e.g. in meshing and conjugate heat transfer. We managed the OpenFOAM Foundation, releasing OpenFOAM v8, packaging OpenFOAM-dev and publishing websites and documentation. During the Covid restrictions, we delivered 67 days of Live Virtual OpenFOAM Training, and provided cloud CFD with CFDDFC® to over 700 subscribers.

With restricted access to the workplace, a CFD engineer can be productive by quickly switching to remote CFD using CFD Direct From the Cloud™ (CFDDFC®) and by learning effective CFD. CFDDFC is a turnkey system with OpenFOAM and supporting software running in its native Linux environment on AWS. Engineers can launch remote instances (virtual machines) in 2 minutes providing remote desktop access to 48 core instances and scalable clusters of 100s of cores. At the same time the engineer can learn to be more productive by registering for our Live Virtual OpenFOAM Training, taken from the safety and comfort of their home using the CFDDFC system.

In 2020, CFD Direct were tasked to develop multicomponent diffusion modelling in OpenFOAM with funding from the Process Engineering Consortium. The Consortium need models, e.g. Maxwell-Stefan, that represent complex diffusion of species in fluid mixtures, affecting both specie concentration and energy. As part of the work, we created a new ThermophysicalTransportModels library with a new interfaces for: fluxes of heat, q() and divq(); and fluxes of mass, j() and divj(). As a consequence, heat transfer became consistent across applications, boundary conditions and data processing. This critical code redesign is typical of our strategy for sustainable development of OpenFOAM, supported by dedicated maintenance funding from OpenFOAM supporters.

CFD Direct has launched CFDDFC® (Arm), a marketplace product on Amazon Web Services (AWS) for computational fluid dynamics (CFD) with OpenFOAM. CFDDFC (Arm) is a variant of CFD Direct From the Cloud™ for Amazon EC2 instances running Arm-based Graviton2 processors, in particular the C6g instances for compute-intensive workloads. CFDDFC (Arm) operates in server-mode without graphical applications and includes OpenFOAM 7 and OpenMPI 4.0.3 running on Ubuntu Server for Arm 20.04 LTS. For batch CFD jobs with guaranteed access on-demand, users can save 35% on their EC2 costs with C6g instances.

In July 2020, CFD Direct released a framework for surface interpolation in interface capturing for multiphase flows in OpenFOAM. All interpolation schemes, used for flux calculation in advection, operate with the MULES-based solvers, e.g. interFoam. The framework is easy to use, extensible, and robust due to bounded, conservative numerics. The new framework comes with a new family of interpolation schemes based on piecewise-linear interface calculation (PLIC). The PLIC schemes provide a promising alternative to standard interface compression, performing better for meshes with regions of cell refinement. All schemes are conservative, bounded and robust and can run efficiently with large time steps.

Many countries have imposed travel restrictions, limited gatherings and encouraged people to self-isolate and work from home due to the COVID-19 pandemic. CFD Direct is therefore re-scheduling some classroom OpenFOAM training as Virtual Training using a video conference between the instructor and participants. Participants work on CFD problems through a remote desktop to OpenFOAM running in the cloud. All machines are accessible to the instructor who can then assist with any problems. Virtual courses will run over a longer schedule and include an extra assistant to support participants during the training.

Your organisation has an expert in CFD with OpenFOAM. They deliver critical results to problems no one else can solve. They have worked there as long as you can remember. Then one day they announce they are leaving and years of experience and know-how walks out of the door. “That-person-left syndrome”, as we call it, is a failure in maintenance which CFD Direct can help with. We provide development, support, training and cloud services to limit the impact of that-person-left syndrome, building a sustainable CFD capability for our customers with OpenFOAM.

CFD Direct From the Cloud™ (CFDDFC) is a Marketplace Product for AWS EC2, that provides a complete platform with OpenFOAM and supporting software running on Ubuntu Linux. It enables simple, fast creation of a cluster of instances to run CFD with OpenFOAM. We tested Amazon EC2 C5n instances, launched in November 2018, on 2 cases of steady-state, external aerodynamics around a car and transient simulation of water flowing over a weir. With meshes of 50-100 million cells, results showed 70%-90% scaling at 504 cores. The cost of the simulations was in the order of $100, compared to $100,000+ to purchase on-premises hardware and licences of proprietary software.

In Year 4 of CFD Direct, we developed new functionality in OpenFOAM and maintained critical components of the code base, reducing the number of unresolved issues by 17%. We managed the OpenFOAM Foundation: promoting sustainable development, releasing OpenFOAM v6, packaging OpenFOAM-dev and publishing websites and documentation. We contributed 1383 man-hours of unfunded work in-kind to OpenFOAM, including organising and presenting at the OpenFOAM Open Day. We delivered 60 days of OpenFOAM Training, and provided low-cost cloud CFD with CFD Direct From the Cloud™, running 1.3 million core-hrs.

OpenFOAM sustainability involves developing software that meets critical needs of users, through a balance of resources, technology, investment and institutional support. The critical needs are availability, usability, robustness and extensibility. The critical work required to meet those needs are publishing, repair and redesign. Employers rarely allocate time to individuals to contribute critical work, so it is generally left to “career maintainers” at CFD Direct. With limited funding, decisions about the critical work are made by those who fund and/or contribute the work, via The OpenFOAM Hub.

In Year 3 of CFD Direct, we developed new functionality in OpenFOAM and maintained critical components of the code base, reducing the number of unresolved issues by 45%. We managed the OpenFOAM Foundation: promoting sustainable development, releasing OpenFOAM v5, packaging OpenFOAM-dev and publishing websites and documentation. We delivered 60 days of OpenFOAM Training, introducing our new “hybrid” classroom-virtual courses to host participants in person and remotely. We launched the new Cloud CFD course to teach inexpensive, secure, efficient CFD with CFD Direct From the Cloud™.

In Spring 2019, CFD Direct is running its OpenFOAM Training courses — Essential CFD, Applied CFD, Programming CFD and Cloud CFD — fully updated with the latest features of the new version 6 release of OpenFOAM. Essential and Applied CFD courses are available — with some remote places for remote attendance — on: 4-7 Feb, London UK; 25-28 Feb, Houston USA; 20-23 May, Cologne Germany; 13-16 Jun, Denver USA. Programming CFD is available 29-31 Jan and 12-14 Mar as Virtual Training.

CFD Direct announces the release of their new 1 day Cloud CFD course, the fourth course in their portfolio of OpenFOAM Training. The course enables users to run CFD with OpenFOAM on AWS, training the tools and processes for inexpensive, secure, efficient cloud use. The course addresses the main concerns of using public cloud: cost management, security, efficient CFD and data management. It exploits the cost benefits of cloud: meeting fluctuating demand for hardware at a cost that represents consistent, high utilitisation; and using cheaper, spare capacity, with an application that does not require 100% availability.

In Autumn 2017, CFD Direct are running their OpenFOAM Training courses — Essential CFD, Applied CFD and Programming CFD — fully updated with the latest features of the new version 5 release of OpenFOAM. Essential and Applied CFD courses are available: 25-28 Sep, London UK, and 16-19 Oct, Chicago USA with limited places via the Internet; 6-9 November, Munich Germany. Programming CFD is available 12-13 Sep and 3-4 Oct as Virtual Training. We use new features in OpenFOAM v5 to give our participants the confidence to carry out CFD analysis, repeatedly, to a defined standard in a timely manner.

In May 2017, we implemented water wave modelling into the public, development line of OpenFOAM (OpenFOAM-dev), to simulate flow conditions experienced in marine and offshore engineering, e.g. on a ship in open water. The initial implementation includes the first order Airy wave and the second order Stokes wave (Stokes II), a second-order accurate utility to apply waves for case initialisation to the entire domain. A verticalDamping source (fvOption) provides wave damping towards outlet regions and an interfaceHeight function object processes interface elevation at specified locations.

At the end of Year 2 of CFD Direct, we summarise our principal activities as the primary contributor to OpenFOAM. We developed new functionality, producing OpenFOAM v4.0 and v4.1, maintaining the OpenFOAM code base, documentation, websites and other infrastructure — where we contributed 1300 man-hours of work in-kind. We delivered 55 days of OpenFOAM Training — Essential, Applied and Programming CFD — as scheduled classroom courses, live virtual training and on-site. We released new versions of our cloud CFD platform, CFD Direct From the Cloud (CFDDFC), and became and Advanced Technology Partner of Amazon Web Services.

In Year 2, CFD Direct handled almost 500 issues on the OpenFOAM issue tracking system. We upgraded the system and and analyzed metrics relating to timely resolution of issues which concluded that current unresolved issues relate to badly designed components of OpenFOAM that require significant code rewriting. To fund that repair work and ongoing maintenance, we ran a successful campaign to raise €100 k from companies that benefit from OpenFOAM. We carried out substantial maintenance to OpenFOAM websites, significant updates to documentation, and administration for the OpenFOAM Foundation.

In Year 2, CFD Direct updated its OpenFOAM cloud computing platform — CFD Direct From the Cloud (CFDDFC) — to OpenFOAM 4.1, running on Ubuntu 16.04. Feedback from users was very positive, including a 5-star rating on the CFDDFC Marketplace Product page at at Amazon Web Services (AWS). We became an Advanced Technology Partner of AWS, and produced a case study on the cost of CFD on AWS EC2 that concluded, in particular, that the cost of Spot instances was approximately 40% of the total cost of ownership of on-premises hardware. We made CFDDFC available on AWS X1 instance types, running simulations on 32 and 64 physical cores in a single instance.

Cloud computing replaces large upfront expenses with low, variable payments that only apply to what you use. CFD simulations cover a range of sizes and complexity. Activity is generally interrupted by quiet periods when simulations are halted, e.g. when a simulation ends non-working hours, during analysis of results or preparation of a new simulation, etc. The fluctuating demand makes CFD well suited to a pay-per-use model. Users need to understand the costs involved to get the best value from cloud and be confident that they fall within budget. This article explains the costs, with an example of an external aerodynamics calculation with OpenFOAM using CFD Direct From the Cloud™ (CFDDFC) on Amazon Web Services (AWS).

Agile development of OpenFOAM emerged following the public distribution of the development line in December 2014. It relies on user participation, which is encouraged by rewarding users for reporting issues with timely resolution. OpenFOAM was in poor health at version 2.3.0, with unresolved issues increasing rapidly and long resolution times. Following the move to agile development, unresolved issues are reduced and under control, with ~70% of issues resolved in 1 day and ~90% resolved in 1 week, taking OpenFOAM to a new level of quality and maturity (always releasable) by version 4.0.

Fluid dynamics is concerned with the motion of fluids (liquids and gases) and the forces on them. “Computational” refers to computation of the flow and forces using numerical analysis. We define “computational fluid dynamics” as “the prediction of fluid motion and forces by computation using numerical analysis, generally extended to include heat, thermodynamics, chemistry and solids”. This definition covers a broad range of calculations for numerous scientific and engineering applications, in particular involving heat.

This article provides information on tensor mathematics, relevant to fluid dynamics and computational fluid dynamics (CFD). It describes scalars and vectors and typical algebraic vector operations. It follows with second rank tensors, their algebraic operations, symmetry, skewness and tensor invariants such as trace and determinant, higher rank tensors, co-ordinate system and change of axis. Tensor calculus is introduced (div, grad, curl and Laplacian), followed by integral theorems of Gauss and Stokes, with a physical representation of div and curl, and more.

In 2017, CFD Direct are running sessions of their OpenFOAM Training courses — Essential CFD, Applied CFD and Programming CFD — fully updated with the latest features of the new version 4 release of OpenFOAM: 24-27 April 2017, Berlin Germany; 16-18 May, Virtual Asia-Pacific; 20-21 June, 26-27 June, Virtual Americas; 4-5 July, London UK; 12-13 Sept, Virtual Americas; 25-28 Sept, London UK; 16-19 October, Chicago USA. OpenFOAM v4 contains new functionality we introduced in OpenFOAM v4 to improve usability so our course participants spend less time struggling with quirks of the software, leaving more time to build and practice their CFD skills.

On 25th March 2015, CFD Direct was launched by Henry Weller (creator of OpenFOAM), Chris Greenshields, and Jenya Collings. At the end of our first year, we summarise our principal activities as the primary contributor to OpenFOAM, producing 3 releases of OpenFOAM, maintaining the OpenFOAM code base, managing the OpenFOAM Foundation, creating a free documentation resource and engaging with the community. We launched 3 training courses — Essential, Applied and Programming CFD — which we deliver as scheduled classroom courses, live virtual training and on-site. We launched CFD Direct From the Cloud (CFDDFC), a complete CFD cloud computing platform using Amazon Web Services EC2.

In April 2015, we launched 2 × 2 day courses, Essential CFD and Applied CFD, which were delivered as scheduled classroom training courses in Berlin, Houston, London, Chicago and Munich. In early 2016 we launched our 2 day course, Programming CFD, which we are delivering initially as Live Virtual Training. Our 3 OpenFOAM Training courses, aimed at competency in CFD, are now run as scheduled classroom courses, live virtual training and on-site training. We believe our comprehensive, modern programme is the best OpenFOAM training, using only free, open source software, for a one-time investment in staff skills without recurring licence fees.

OpenFOAM is free software, meaning users have the freedom to run, copy, distribute, study, change and improve the software. Users benefit from these freedoms, which account for much of OpenFOAM’s popularity. The OpenFOAM Foundation is the copyright holder of OpenFOAM, which it licenses exclusively under the GPL. It maintains a strong legal position to enforce the licence and preserve its freedoms, by being the single owner of OpenFOAM. This requires contributors to the project to assign copyright in their OpenFOAM contributions to it, through its Contributor Agreement. Organisations with a serious commitment to free software are signing the Agreement, including CFD Direct, blueCAPE, VTT Technical Research of Finland Ltd and Intel.

In January-March 2016, CFD Direct are running sessions of their OpenFOAM Training courses — Essential CFD and Applied CFD — fully updated with the latest features of the new version 3.0 release of OpenFOAM: 25-28 January 2016, London UK; 22-25 February 2016, Houston USA; 7-10 March 2016, Berlin Germany. OpenFOAM v3.0 contains new functionality we introduced in OpenFOAM v3.0 to improve usability so our course participants spend less time struggling with quirks of the software, leaving more time to build and practice their CFD skills.

CFD Direct are running 2 pilot sessions of their new OpenFOAM Training courses on: 1-4 June 2015, Berlin, Germany; 15-18 June 2015, Houston, TX USA. The 2×2 day courses, Essential CFD and Advanced CFD, have been developed to enable people to deliver successful CFD solutions with OpenFOAM. The new courses are a result of 6 months development, built on our experience as the Architects of OpenFOAM and of training 2500 people with OpenFOAM.

In 2008, the Directors of CFD Direct began the first significant OpenFOAM Training courses. The training was written for early adopters of OpenFOAM at a time when OpenFOAM was far less functional than today. The courses largely emphasised how OpenFOAM worked and a lot of time was devoted to code customisation. We pioneered a convenient method of providing participants with a running version of OpenFOAM using a persistent live installation that booted Linux from an 8GB USB pendrive. The wider user community benefited from our example cases, e.g. the motorbike case, and code changes made for the courses becoming part of OpenFOAM and our adoption of Ubuntu leading to the release of OpenFOAM packaged for Ubuntu.