Adaptive software for high-fidelity simulations of multi-phase turbulent reacting flows

Lead Research Organisation: Newcastle University
Department Name: Sch of Engineering

Abstract

This project focuses on the development, validation and documentation of a next-generation fully parallelised computa-tional fluid dynamics (CFD) code called HAMISH based on adaptive mesh refinement (AMR) which will enable high-fidelity Direct Numerical Simulations (DNS) of advanced turbulent reacting flows such as flame-wall interaction, localised ignition, and droplet combustion including atomisation processes. Such simulations cannot be achieved at present without limiting simplifications due to their prohibitive computational cost. AMR for large-scale highly-parallel simulations of compressible turbulent reacting flows is a significant new functionality which will offer major benefits in terms of computational economy for problems involving thin fluid-mechanical structures, e.g. resolution of both the flame and the boundary layer in flame-wall interaction, droplet surfaces in atomisation in spray combustion, shock waves in localised forced ignition, etc. Such structures have either been ignored or simplified severely in previous work due to the prohibitive computational cost of fixed global meshes, thus limiting the usefulness of the simulations. Hence AMR will offer a step-change in capability for the computational analysis of turbulent reacting flows, and will provide data with the degree of detailed physical information which is not currently available from simulations using existing CFD codes. The proposed software will be validated with respect to the results obtained from the well-proven uniform-mesh DNS code SENGA2, which has already been ported to ARCHER and is currently widely used by members of the UK Consortium on Turbulent Reacting Flows (UKCTRF). The newly developed code, HAMISH, will not only be ported to ARCHER, but also be prepared for architectures supporting accelerators thanks to OpenMP 4.5, which will support OpenACC, targeting a POWER8 cluster. As a part of this project, a detailed user guide will be produced at each new release of the code. This user guide will be made available on a website for public download along with the open-source version of the code and the associated documentation on code validation and user tutorials.

Planned Impact

(i)Development of fundamental understanding and modelling of turbulent reacting flows: The design-cycle of modern combustors and fire-safe engineering structures depends heavily on the predictive capability of advanced CFD calculations. The adaptive mesh refinement (AMR) based CFD software developed during the course of this project will make it possible to carry out advanced turbulent reacting flow simulations (e.g. FWI, ignition with shock wave formation, and spray combustion with atomisation etc.), which were hitherto either impossible or extremely expensive to conduct. Furthermore, the newly developed CFD software HAMISH will not only utilise the current High Performance Computing (HPC) facilities but also will be made compatible for the next generation UK National computer, including hybrid MPI+OpenMP & MPI+OpenACC for GPUs, and other accelerators. The DNS simulations, to be carried out based on HAMISH, will yield important fundamental physical insights, which in turn can be used for the development of high-fidelity models for turbulent reacting flows. This exercise will offer maxi-mum benefit for manufacturers of new generation Internal Combustion (IC) engines and gas turbines, who are engaged in developing new low-pollution and high efficiency engines. In the UK, Renuda, Rolls-Royce and Siemens are involved in the Impact Advisory Panel (IAP) of UK Consortium on Turbulent Reacting Flows (UKCTRF) who will be interested in the outcome of this work, though the benefits are not limited to the UK as important findings will be disseminated through leading peer-reviewed journals (Journal of Computational Physics, Computers and Fluids, Combustion and Flame, Combustion Theory and Modelling, Physics of Fluids etc.) and international conference (Parallel CFD, PARENG, International Combustion Symposium, European Combustion Meeting, SIAM Numerical Combustion Conference etc.) publications.

(ii) Engagement with industry: In order to maximise the impact of the project, the PI, CIs and RAs will work actively to publicise the results by attending reputed international conferences and important UK combustion meetings organised by the British Combustion Institute and Institute of Physics and UKCTRF. The outcomes of the project will be widely disseminated to the members of UKCTRF and industrial IAP members by utilising the UKCTRF meetings and hosting a website linked with UKCTRF website.The website will be maintained during the course of this project to promote and disseminate the newly developed code HAMISH. On the website, links will be provided for easy access to the source code, information regarding code validation, user manual and tutorials for potential users. This website will be particularly important for commercial CFD companies who will have cutting-edge information on the subject, and can implement the models in industrial CFD codes.

(iii) Manpower development: The proposed project is based on the collaboration between three different turbulent reacting flow research groups in the UK, which will ensure an extensive knowledge exchange. This project will not only broaden the expertise of the investigators but also be highly valuable for the RAs for their academic and career development. The RAs will receive extensive training on a variety of topics such as advanced CFD techniques (e.g. AMR), thermo-fluid mechanics, turbulence, and combustion physics. They will also learn advanced techniques for for high performance computing, which will improve their analytical and mathematical skills. This project lays substantial emphasis on on the development of both technical and transferable skills of the RAs, which, in turn, increases the chances of their employability. As a result of this, this project has high impacts in terms of developing highly skilled UK based workforce and this benefit will be felt in 3-5 years' time-scale.

Publications

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Klein M (2018) Flame Curvature Distribution in High Pressure Turbulent Bunsen Premixed Flames in Flow, Turbulence and Combustion

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Malkeson SP (2017) Droplets and Sprays

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Zhao P (2019) Vectorial structure of the near-wall premixed flame in Physical Review Fluids

 
Description Flow physics and mesh refinement
Developing an AMR code raises challenges in the programming methodology and software management. Mesh refinement and de-refinement are strongly case dependent, and the mesh has to change dynamically and rapidly depending on the local flow physics. The flow physics has to be well understood in the development and optimisation of the AMR trigging strategy, especially for complex flows in combustion, where multi-phase flow, droplets, chemical reaction, wall turbulence and shock-waves are all involved.

Parallelisation of the code
In-depth parallelisation is another challenge for complex AMR code. In addition to conventional parallelisation based on MPI, vectorisation of the code would improve the performance of the code on accelerators, improving data locality of the AMR code. To further boost the performance on modern HPC architectures, it is intended to implement the hybrid MPI-OpenMP model, with OpenMP 4.5 from OpenACC on accelerators.

Multi-phase capability
To capture atomisation and evaporation of droplets in combustion, a combined multi-phase reacting flow solver has to be developed. It will rely on Volume-of-fluid (VOF) method. However, the conventional VOF method is not accurate enough to capture the surface geometry of droplets and to compute the surface tension, which is critical in the evaporation process. Although AMR will help in refining the mesh around the droplets and improving the accuracy, it is still a key issue and a challenge to develop a high-accuracy front-tracking VOF method to integrate it into a parallel AMR-based code, with adequate performance.

Data analysis tools
Post-processing methods based on adaptive unstructured meshes are required so that volume-rendering based visualisation and the extraction of flow structures can be done with ease.
Exploitation Route This project is funded by the EPSRC (EP/P022286/1). The project focuses on the development, validation and documentation of a next-generation fully parallelised computational fluid dynamics (CFD) code called HAMISH. This code is based on adaptive mesh refinement (AMR) which will enable high-fidelity Direct Numerical Simulations (DNS) of advanced turbulent reacting flows such as flame-wall interaction, localised ignition, and droplet combustion including atomisation processes. Such simulations cannot be achieved at present without limiting simplifications due to their prohibitive computational cost. AMR for large-scale highly-parallel simulations of compressible turbulent reacting flows is a significant new functionality which will offer major benefits in terms of computational economy for problems involving thin fluid-mechanical structures, e.g. resolution of both the flame and the boundary layer in flame-wall interaction, droplet surfaces in atomisation in spray combustion, shock waves in localised forced ignition, etc. Such structures have either been ignored or simplified severely in previous work due to the prohibitive computational cost of fixed global meshes, thus limiting the usefulness of the simulations. Hence AMR will offer a step-change in capability for the computational analysis of turbulent reacting flows, and will provide data with the degree of detailed physical information which is not currently available from simulations using existing CFD codes. The proposed software will be validated with respect to the results obtained from the well-proven uniform-mesh DNS code SENGA2, which has already been ported to ARCHER and is currently widely used by members of the UK Consortium on Turbulent Reacting Flows (UKCTRF). The newly developed code, HAMISH, will not only be ported to ARCHER, but also be prepared for architectures supporting accelerators thanks to OpenMP 4.5, which will support OpenACC, targeting a POWER8 cluster. As a part of this project, a detailed user guide will be produced at each new release of the code. This user guide will be made available on a website for public download along with the open-source version of the code and the associated documentation on code validation and user tutorials.
Sectors Aerospace, Defence and Marine,Energy,Environment,Other

URL http://www.ukctrf.com/flagship-software-grant/
 
Description Impact by exploitation of project outcomes, and through engagement of beneficiaries: The design-cycle of modern combustors and fire-safe engineering structures depends heavily on the predictive capability of advanced CFD calculations. The adaptive mesh refinement (AMR) based software developed during the course of this project will make it possible to carry out advanced turbulent reacting flow simulations (e.g. FWI, ignition with shock wave formation, and spray combustion with atomisation etc.), which were hitherto either impossible or extremely expensive to conduct. Furthermore, the newly developed DNS code HAMISH will not only utilise the current High Performance Computing (HPC) facilities but also will be made compatible for the next generation UK National computer, including hybrid MPI+OpenMP & MPI+OpenACC for GPUs, and other accelerators. The DNS simulations, to be carried out based on HAMISH, will yield important fundamental physical insights, which in turn can be used for the development of high-fidelity models for turbulent reacting flows. This exercise will offer maximum benefit for manufacturers of new generation Internal Combustion (IC) engines and gas turbines, who are engaged in developing new low-pollution and high effi-ciency engines. In the UK, Rolls-Royce and Siemens are involved in the Impact Advisory Panel (IAP) of the UK Consor-tium on Turbulent Reacting Flows (UKCTRF), alongside smaller companies such as Renuda, who will be interested in the outcomes of this work (see letter of support from Renuda as an example), though the benefits are not limited to the UK as important findings will be disseminated through leading peer-reviewed journals (Journal of Computational Phys-ics, Comp. Fluids, Comb. Flame, Comb.Theor. Modell., Phys. Fluids etc.) and international conferences (Parallel CFD, PARENG, Int. Comb. Symp., Eur. Comb. Meeting, SIAM Num. Comb. Conference, AIP annual Fluid Dynamics etc.) and publications. In order to maximise the impact of the project, the Principal Investigator (PI), Co-investigators (CIs) and Research As-sociates (RAs) will work actively to publicise the results by attending reputed international conferences (see a list in the paragraph above) and important UK combustion meetings organised by the British Comb. Inst. and Inst. of Phys. and UKCTRF. Some funding for this purpose has been requested in the Justification for Resources. The outcomes of the project will be widely disseminated to the members of UKCTRF and industrial IAP members by utilising the UKCTRF meetings and hosting a website linked with UKCTRF website. Many of the investigators of UKCTRF are already en-gaged in industrial collaborations, and will use their contacts to promote the new findings and embed the new knowledge in industry, so that the project benefits are felt in the industrial sector in a relatively short amount of time. In-dustrial colleagues attend the progress review meetings of UKCTRF and these meetings will be utilised to make them aware of the developments in the analysis and modelling of turbulent reacting flows, and their feedback will be taken on board for subsequent steps of the project. Given the long term nature of the design-cycle of IC engines and gas turbines, and the time required to build up enough confidence in the community, it is likely that the impact in terms of new product and wealth creation in the UK will be felt in a time scale of 10-20 years after the completion of the project. The techno-logical advancements of this project will also help in designing energy-efficient and environment-friendly combustors especially for the UK based industries (e.g. Rolls-Royce, Siemens etc.), which will also bring a long-term benefit (~10-20 years) for society. An interactive website will be maintained during the course of this project to promote and disseminate the newly de-veloped code HAMISH. On the website, links will be provided for easy access to the source code, information regarding code validation, user manual and tutorials for potential users. In addition to that the website will list the journal publica-tions resulting from this project, and will contain information on data-exchange and documentation, and specific results will be made available for public download. This website will be particularly important for commercial CFD companies who will have cutting-edge information on the subject, and can implement the models in industrial CFD codes. The im-pact of this project in terms of proving a competent CFD software tool for engineering design processes is likely to be felt in about 5-10 years' time after the completion of the project. The website will also have 'community outreach' features, such as a non-specialist introduction (e.g. for school and undergraduate students) to combustion and its relevance. The non-specialist information will attract school and undergraduate students towards the analysis of turbulent reacting flows and this will have far-reaching impact in terms of recruiting new PhD students and sustaining this line of research in the UK. The PI and CIs have existing collaborations with international research laboratories (Tokyo Institute of Technology, University of Federal Armed Forces, Germany etc.) and the research carried out will be publicised during visits to these laboratories, and visits to collaborators. Members of the Impact Advisory Panel from the non-UK institutions will also act as vehicles for dissemination of the research outcomes of the UKCTRF. Impact through collaboration: The collaboration and the exchange in research expertise between three UK-based research groups with an international reputation are key strengths of this proposed research programme. The interaction with the UKCTRF members and their expert advice during the course of this grant period will be mutually beneficial. Moreover, academic and industrial contacts of the members of the UKCTRF will be beneficial for the purpose of disseminating the research findings of this project in both academia and industry. The collaboration with research groups during the course of this research programme will add new dimensions to the academic developments of the RAs. They will also have opportunities to interact with the experts from both academic and industrial sectors, which will help their academic development, and also help them to develop a range of transferable skills such as communication, teamwork and project management. This, in turn, will give an edge to the RAs in the current competitive job market and encourage them to contribute positively to the Research Software community in the UK. Moreover, the RAs need to pre-sent their work periodically in progress review meetings, which will also be beneficial for them in terms of developing project management and presentation skills. The research outcomes will be publicised in leading international confer-ences, and annual progress review meetings which are expected to initiate valuable discussions with other UK and in-ternational colleagues (especially with the members of the IAP), and open up possibilities for further collaborations. This is likely to initiate plans for future collaborative venture which may also involve exchange visits of RAs and PhD stu-dents. Impact through capability development and knowledge exchange: The proposed project is based on the collaboration between three different turbulent reacting flow research groups (i.e. CUED+DL+NU) in the UK, which will ensure an extensive knowledge exchange between PIs, CI, and RAs working in this project. This project will not only broaden the expertise of the investigators but also be highly valuable for the RAs for their academic and career devel-opment. The RAs will receive extensive training on a variety of topics such as advanced CFD techniques (e.g. AMR), turbulence, and combustion physics. They will also learn advanced techniques for high performance computing, which will improve their analytical and mathematical skills. This project lays substantial emphasis on the development of both technical and transferable skills of the RAs, which, in turn, increases the chances of their employability. Thus, this project has high impacts in terms of developing highly skilled UK based workforce and this benefit will be felt in 3-5 years' time-scale. It is noted earlier that the research outcomes will be presented in front of different academic and industrial col-leagues at different stages of the project to disseminate its findings to the maximum extent, which will ensure knowledge exchange from academic institutions to interested parties in the industrial sector. The expertise generated during the course of this grant will also help in expanding the research group of the investigators (i.e. PI and CIs) in their respective institutions. The impact through capability development will be felt immediately through the RAs, and the expertise developed during the course of the project is likely to bring long term benefits to the investigators and their respective institutions in terms of future funding and the expansion of their respective research groups.
First Year Of Impact 2017
Sector Aerospace, Defence and Marine,Energy,Environment,Transport,Other
Impact Types Societal,Economic