Thermal and Reactive Flow Simulation on High-End Computers

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Thermal and reactive flows are cross-cutting fundamental disciplines that have found applications in technologies such as aerospace engineering, combustion engines for power generation and propulsion, geothermal energy, solar thermal energy, bioenergy, nanotechnology, chemical engineering and climate science, etc. Research in the field is a prime example where high-end computing (HEC) can have a crucial impact, as the reliability and accuracy of numerical prediction and diagnosis of thermal and reactive flows are directly linked to the computational grid resolution and the size of the time steps. The reason lies with the extremely wide range of time and length scales present in thermal and reactive flows, which are typically turbulent as well. There are 9 to 12 orders of magnitude change between the smallest and the largest length and time scales present in thermal and reactive flows of technical relevance, which should ideally be resolved by experimental measurement or numerical simulation. To study such complex phenomena by experiment alone would be prohibitively expensive and laborious if possible at all. Numerical simulation, on the other hand, offers non-intrusive, virtual "measurement" of all relevant quantities at desired resolution and accuracy, provided sufficient computing power is available. Over the past two decades, the world has first seen gigaflops supercomputers, then teraflops and more recently petaflops machines. The pace of development towards exa-scale HEC platforms has recently quickened. Only last autumn, Tianhe-1A caused a stir by reaching 2.566 petaflops maximum sustained calculation speed, but six months later the K computer achieved an astonishing 8.162 petaflops. At least two HEC machines with 20 petaflops are being built in the world and expected to enter service next year (http://www.top500.org/). The problem is that advance in supercomputing hardware and software, impressive as it appears, has barely kept pace with the research needs. Therefore, frontier research in computational thermal and reactive flows tends to be strongly associated with making use of the latest HEC available. We believe that HEC is a key enabler of cutting-edge research in thermal and reactive flow flows. The main purpose of this application is to secure HEC resources on HECToR and its successors to support funded research projects in the field. These include: (a) K H Luo (P.I.), EPSRC grant No. EP/I016570/1 (09/2011 - 08/2014), "Tackling Combustion Instability in Low-Emission Energy Systems: Mathematical Modelling. Numerical Simulations and Control Algorithms"; (b) K H Luo (P.I.) and R W Eason, EPSRC grant No. EP/I012605/1 (05/2011 - 05/2014), "Laser-Induced Forward Transfer Nano-Printing Process - Multiscale Modelling, Experimental Validation and Optimization"; and (c) N D Sandham (P.I.), on-going LAPCAT II EU/FP7, "Long-term advanced propulsion concepets and technologies". In addition, the widely used SBLI code first developed by the applicants will be extended to incorporate capabilities for reactive flow simulation. By making use of the world-class computing facility HECToR, the above projects will fulfil the objectives of producing significant, world-leading research results. Examples of world-first simulations will include: (a) largest direct numerical simulation of a turbulent premixed flame interacting with acoustic waves (b) lattice Boltzmann simulation of the complete Laser-Induced Forward Transfer (LIFT) process; and (c) large-eddy simulation of a complete nose-to-tail scramjet engine. These projects are of direct interest to large research communities in aerospace engineering, combustion, nanotechnology, high-performance computing and so on, and will involve a dozen UK and EU companies, which will ensure wide and timely dissemination of research results.