Wim Nieuwpoort Award for research into bubbly turbulence
03 JAN 2018
Dr. Paolo Cifani from the Multiscale Modeling and Simulation group at the University of Twente has been awarded the Wim Nieuwpoort Award 2017. The winner was announced at the Super D Event on December 12, 2017.
According to the jury the work shows “very good (super-linear) ‘strong scaling’ while solving a problem with a fairly high degree of complexity, namely that of turbulent flow in a two-phase system with bubbles”. The scaling results (see figure 1), were obtained from running their code on National Supercomputer Cartesius in parallel, with a maximum of 17664 cores.
Fig.1: Wall clock time per time-step (Ct) as a function of the number of cores for a grid corresponding to about 126 million points (red line), and for a grid corresponding to about 1 billion points (blue line). The dashed line indicates linear scaling.
The project, from the research group led by prof. dr. ir. Bernard Geurts, deals with numerical simulation of turbulent bubble-laden channel flows. The carrier fluid is a liquid that transports dispersed gas bubbles. The unique feature of the project is the inclusion of general deformability of these bubbles, extending very recent work on dispersed non-deformable particles.
Figure 2: contour levels of the stream-wise velocity component for different slices a of bubbly channel flow at shear Reynolds number 127. The flow direction is along the x axis. The deformable bubbles are represented by grey objects, which are the computed isosurfaces f = 0.5 (with f the gas volume fraction). The channel is loaded with 1152 bubbles corresponding to a total volume fraction of 10%.
Turbulent bubbly flow, c.f. Figure 2, is encountered in many practical applications. Examples are heat exchangers in power plants, or cooling systems of nuclear reactors. The simultaneous existence of physical phenomena spanning a wide range of scales of motion is certainly one, if not the most, complex aspect of bubbly multiphase flows. Numerical simulation is a useful and powerful tool for a better understanding of the physics of such systems. In this work, the attention is turned to direct numerical simulation (DNS), where all the details of the flow, up to the smallest dynamically relevant scales, are resolved by the computational grid and time steps. DNS provides insights in the fundamental behavior of multiphase flows, such as how bubbles affect the flow field, how they cluster preferentially and develop intriguing streaky structures, and what forces act on a bubble-liquid interface deforming it.
About the prize
The annual Wim Nieuwpoort Award is awarded to the research team, located at a Dutch university or scientific institute, which proves to be able to run a serious scientific application efficiently on a significant part of the Dutch national HPC infrastructure (Cartesius).
The award consists of a combined prize of € 2500 and a visit to the annual supercomputing & communications conference SC2018 to be held coming November in Dallas, USA. During the conference, the winner’s research and scalability results can be presented in our SURF booth.
The jury – a subcommittee of NWO’s advisory committee for the Scientific Use of Supercomputers WGS – appoints a winner based on the following criteria:
- Quality of the scientific research
- Parallel (strong) scalability achievements of the implementation
- The share of own work in developing, parallelizing, optimizing and scaling the code
- Usability of the implementation in other scientific areas
The award is named after the founder of the national high-performance computing infrastructure in the Netherlands: professor emeritus Wim Nieuwpoort of the University of Groningen. Wim Nieuwpoort has been chair of NWO/NCF’s Scientific Committee (WGS) and temporary director of SARA Computing and Network Services.
Prof. dr. Wim Nieuwpoort (left) and prof. dr. ir. Anwar Osseyran, member of the board of SURF (middle) handing out the award to dr. Paolo Cifani from the University of Twente at the annual Super D event on December 12th in the Westergasfabriek, Amsterdam (photo Vera Duivenvoorde)