CCP Turbulence

Lead Research Organisation: Imperial College London
Department Name: Aeronautics

Abstract

Our daily life is surrounded - and even is sustained - by the flow of fluids. Blood moves through the vessels in our bodies, and air flows into our lungs. Fluid flows disperse particulate air pollution in the turbulent urban as well as indoor environments. Fluid flows play a crucial role for our transportation and our industries. Our vehicles move through air and water powered by other fluids that mix in the combustion chambers of engines. Many of the environmental and energy-related issues we face today cannot possibly be tackled without a better understanding of the dynamics of fluids.

From a practical point of view, fluid flows relevant to scientists and engineers are turbulent ones; turbulence is the rule, not the exception. To date, a complete theory of fluid flow phenomena is still missing because of the complexity of the full equations describing the motion of a fluid. Their understanding and control is however crucial to improve technologies especially with minimal ecological impact as well as to anticipate events, in many areas ranging from engineering applications (e.g., industrial process, propulsion and power generation, car and aircraft design) to environmental sciences and technologies (e.g., air quality, weather forecasting, climate predictions, flood disasters monitoring).

Significant progress has been made recently using high performance computing, and computational fluid dynamics is now a critical complement to experiments and theories. The CCP Turbulence is aiming to (i) considerably enhance the UK capabilities to simulate complex turbulence problems that were until very recently beyond imagination, (ii) offer user support, training and networking activities and (iii) enable capability computing on emerging hardware platforms. The software developments and collaborative activities will give UK researchers a unique opportunity to be the first to explore new physics and to answer basic questions regarding the physics and modelling of turbulent flows found across a range of engineering, physiological and geophysical applications.

Planned Impact

The research to be carried out thanks to the software developments and collaborative activities from the CCP turbulence is relevant to the transportation, energy supply/generation, biomedical and process sectors in the UK and the world. In addition to creating new software, knowledge and training for the next generation of engineers and scientists, the proposed software developments and the resulting scientific outputs will deliver benefits to the economy and allow the UK to realise its societal goals.

Despite being the largest contributors to harmful emissions, the transportation, energy generation/supply and process sectors are experiencing unprecedented growth around the world. For example, it is estimated that more than 29,000 new large civil airliners, 24,000 business jets, 5,800 regional aircraft and 40,000 helicopters will be required worldwide in 2032 to deal with the constant increase of worldwide air traffic. It is predicated that by 2025 there will be more than 16 billion passengers per year worldwide. The UK is directly concerned by this challenge as it is the second biggest national aerospace industry in the world, with a 17% global market share for a turnover of more than £20 billion every year, sustaining more than 200,000 jobs. Aviation will need to find ways to meet this impressive growing demand whilst reducing its environmental impact - specifically the noise levels and carbon emissions. This can only be achieve with a state-of-the-art ecosystem of softwarewith better understanding of the overarching subject of turbulence. Many of the CCP members, with AIRBUS and the US Air Force, are currently working on drag reduction techniques for airplanes, high-speed trains, automotive vehicles and over the hulls of ships and submarines. Even a 1% reduction in drag can save at least 25,000 gallons of fuel per year per aircraft. Worldwide, this reduction could translate to fuel savings of more than $1 billion per year. The resulting reduction in emissions into the air is equally as impressive.

Since the mid-1990s, Computational Fluid Dynamics (CFD) has been integrated into industrial design and engineering processes, playing a decisive role in improving the quality and efficiency of complex products and significantly reducing the time to market. High Performance Computing has enabled simulations at a higher level of precision and complexity, significantly impacting new areas of research. CFD is now recognised as a driver of economic growth and societal well-being and is vital for maintaining international competitiveness. The UK has a long history in Europe of developing cutting-edge applications dedicated to CFD. Because of the rapid evolution of the enabling technologies and the expanding range of applications demand, the UK needs to support and encourage this CCP, which can produce new knowledge via a robust state-of-the-art software ecosystem, help to design innovative products and reduce cost and time of their implementation in real life applications. A striking example is the recent purchase by Siemens of the CFD software company CD-Adapco for $970M which clearly shows that better turbulence models and accurate simulations that can improve engineering design for a great range of applications are crucially needed by industries. Rolls-Royce, heavily involved with several members of the CCP, believes that the activities from the CCP are crucial to gain insights into turbulence physics and would enabled them to better understand limitations of their current CFD approaches and how to devise improvement strategies to take a competitive lead. This interest is shared by an F1 team who is pushing to embrace leading edge simulation techniques that help gain a fundamental understanding of the flow environments that dictate the performance of road and race cars.

Publications

10 25 50
 
Description The software development activities have allowed us to use supercomputers based on accelerator technologies.
Exploitation Route All our software are open-source and freely available to the scientific community
Sectors Aerospace

Defence and Marine

Education

Energy

Transport

URL http://www.ukturbulence.co.uk
 
Description Turbulence at the exascale: application to wind energy, green aviation, air quality and net-zero combustion
Amount £2,670,328 (GBP)
Funding ID EP/W026686/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 12/2021 
End 11/2025
 
Description Turbulent Flow Simulations at the Exascale: Application to Wind Energy and Green Aviation
Amount £254,329 (GBP)
Funding ID EP/V000942/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 08/2020 
End 06/2022
 
Description NVIDIA 
Organisation NVIDIA
Country Global 
Sector Private 
PI Contribution --> discussion with NVIDIA with the aim to prepare a proposal for the ExCALIBUR project (software development)
Collaborator Contribution --> discussion with NVIDIA with the aim to prepare a proposal for the ExCALIBUR project (software development)
Impact --> preparation of a proposal for the ExCALIBUR project (software development)
Start Year 2020
 
Description SIEMENS SOFTWARE 
Organisation Siemens industry Software
Country United Kingdom 
Sector Private 
PI Contribution Imperial College London: development of state-of-the-art turbulence models
Collaborator Contribution Imperial College London: development of state-of-the-art turbulence models
Impact See list of publications
Start Year 2019
 
Description The Numerical Algorithms Group (NAG) 
Organisation Numerical Algorithms Group Ltd
Country United Kingdom 
Sector Private 
PI Contribution --> new capabilities in the OPS library
Collaborator Contribution --> new capabilities in the OPS library
Impact --> new capabilities in the OPS library
Start Year 2020
 
Title 2DECOMP&FFT 
Description The 2DECOMP&FFT library is a software framework written in modern Fortran to build large scale parallel applications. It is designed for applications using three-dimensional structured meshes with a particular focus on spatially implicit numerical algorithms. However, the library can be easily used with other discretisation schemes based on a structured layout and where pencil decomposition can apply. It is based on a general-purpose 2D pencil decomposition for data distribution and data Input Output (I/O). A 1D slab decomposition is also available as a special case of the 2D pencil decomposition. The library includes a highly scalable and efficient interface to perform three-dimensional Fast Fourier Transforms (FFTs). The library has been designed to be user-friendly, with a clean application programming interface hiding most communication details from application developers, and portable with support for modern CPUs and NVIDIA GPUs (support for AMD and Intel GPUs to follow). 
Type Of Technology Software 
Year Produced 2023 
Open Source License? Yes  
Impact Possibility to use GPU hardware 
URL https://www.theoj.org/joss-papers/joss.05813/10.21105.joss.05813.pdf
 
Title OpenSBLI 
Description OpenSBLI is a Python-based modelling framework that is capable of expanding a set of differential equations written in Einstein notation, and automatically generating C code that performs the finite difference approximation to obtain a solution. This C code is then targetted with the OPS library towards specific hardware backends, such as MPI/OpenMP for execution on CPUs, and CUDA/OpenCL for execution on GPUs. The main focus of OpenSBLI is on the solution of the compressible Navier-Stokes equations with application to shock-boundary layer interactions (SBLI). However, in principle, any set of equations that can be written in Einstein notation may be solved. 
Type Of Technology Software 
Year Produced 2019 
Open Source License? Yes  
Impact See list of publications 
URL https://opensbli.github.io/
 
Title Xcompact3d 
Description Xcompact3d is a Fortran-based framework of high-order finite-difference flow solvers dedicated to the study of turbulent flows. Dedicated to Direct and Large Eddy Simulations (DNS/LES) for which the largest turbulent scales are simulated, it can combine the versatility of industrial codes with the accuracy of spectral codes. Its user-friendliness, simplicity, versatility, accuracy, scalability, portability and efficiency makes it an attractive tool for the Computational Fluid Dynamics community. XCompact3d is currently able to solve the incompressible and low-Mach number variable density Navier-Stokes equations using sixth-order compact finite-difference schemes with a spectral-like accuracy on a monobloc Cartesian mesh. It was initially designed in France in the mid-90's for serial processors and later converted to HPC systems. It can now be used efficiently on hundreds of thousands CPU cores to investigate turbulence and heat transfer problems thanks to the open-source library 2DECOMP&FFT (a Fortran-based 2D pencil decomposition framework to support building large-scale parallel applications on distributed memory systems using MPI; the library has a Fast Fourier Transform module). When dealing with incompressible flows, the fractional step method used to advance the simulation in time requires to solve a Poisson equation. This equation is fully solved in spectral space via the use of relevant 3D Fast Fourier transforms (FFTs), allowing the use of any kind of boundary conditions for the velocity field. Using the concept of the modified wavenumber (to allow for operations in the spectral space to have the same accuracy as if they were performed in the physical space), the divergence free condition is ensured up to machine accuracy. The pressure field is staggered from the velocity field by half a mesh to avoid spurious oscillations created by the implicit finite-difference schemes. The modelling of a fixed or moving solid body inside the computational domain is performed with a customised Immersed Boundary Method. It is based on a direct forcing term in the Navier-Stokes equations to ensure a no-slip boundary condition at the wall of the solid body while imposing non-zero velocities inside the solid body to avoid discontinuities on the velocity field. This customised IBM, fully compatible with the 2D domain decomposition and with a possible mesh refinement at the wall, is based on a 1D expansion of the velocity field from fluid regions into solid regions using Lagrange polynomials or spline reconstructions. In order to reach high velocities in a context of LES, it is possible to customise the coefficients of the second derivative schemes (used for the viscous term) to add extra numerical dissipation in the simulation as a substitute of the missing dissipation from the small turbulent scales that are not resolved. Xcompact3d is currently being used by many research groups worldwide to study gravity currents, wall-bounded turbulence, wake and jet flows, wind farms and active flow control solutions to mitigate turbulence. 
Type Of Technology Software 
Year Produced 2019 
Open Source License? Yes  
Impact see list of publications 
URL http://www.incompact3d.com
 
Description Podcast "Turbulence at the Exascale 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact The UK Turbulence Consortium and the UK ExCALIBUR project on turbulence at the exascale have launched a podcast on "Turbulence at the exascale" to gather the views of the community about the opportunities and the challenges that will come with exascale computing for turbulent flows in the UK.
Year(s) Of Engagement Activity 2020
URL https://www.ukturbulence.co.uk/excalibur-podcast.html
 
Description Training and hackathon activities 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact various training sessions and hackathons were organised to show other scientists how to use our software
Year(s) Of Engagement Activity 2023
 
Description Twitter account for the UK Turbulence Consortium 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Twitter account for the UK Turbulence Consortium
Year(s) Of Engagement Activity 2018,2019
URL https://twitter.com/ukturbulence
 
Description online series of talks dedicated to turbulence research based on the UK supercomputing facility 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact As it is not possible to organise the usual in-person annual meetings (and it is very unlikely that we will be able to do so anytime soon), the UKTC management committee and the CCP Turbulence launched online talk series dedicated to to turbulence research based on the UK supercomputing facility.

The idea is very simple: every research group who had access to ARCHER resources in the last 2 years presents their work virtually, in dedicated sessions. Each session, with 4 talks, will last a maximum of 1h30 and focuses on a particular topic.
Year(s) Of Engagement Activity 2020
URL https://www.ukturbulence.co.uk/on-line-talks-2021.html