The objective of CFML
The attempt to regard the real phenomena as "Complex-system" in various field of engineering and science is now focusing on. The fluid phenomenon which has the non-linear effect and large degrees of freedom is one of the typical complex systems. In order to understand it, there were a lot of theoretical and experimental approaches. Recently, "Numerical simulation", which is based on using the high-spec computer, is now focusing on as the third way. In order to apply computational simulation for analysis and prediction of various complex phenomena related to flow (e.g. turbulent flow, bubble and spray flow, combustion flame, noise and vibration caused by fluid, and aerodynamic heating and heat conductivity) and utilize it for engineering design, we need various things related to mechanical, informational, and physical techniques as below.
・Physical understanding of the flow
・Reasonable mathematical models
・Accuracy and efficiency of computation
・Graphical-interface for handling enormous data
・Comupter and network environment for realizing the simulation
In this laboratory, we utilize Large-Eddy-Simulation(LES) as a rational computational prediction of unsteady and 3-dimensional turbulent phenomena and focus on thermal and fluid physics models which can deal with complex flows with chemical reactions and phase change. We are developing fundamental numerical models, computational methods, and analyzing tools for utilizing CFD as engineering applications. In order to utilize these numerical simulations for engineering design, we head for these things as below.
・Dealing with real and complex fluid phenomena
・ Precise evaluation of accuracy(=errors) and reliability(=application range)
・Realizing MBD(Model-based Development); Analyzing the causes of phenomena→Evaluation of the design criteria→Designing of machine specs
Developing the next generational software for analysis of fluid phenomena
In this laboratory, we develop the next generational software for analysis of fluid phenomena and its validation in order to apply LES, which is famous as a computational prediction of turbulent flow, and high-order unsteady simulation of complex flow (e.g. reaction and phase change) for engineering design. Up to now, we realized the three methods below in order to reproduce the complexities of practical flow design.
・Simulation of unsteady and 3-dimensional simulation of turbulent flow
・Modeling of complex flow (e.g. reaction flow and multi-phase flow)
・Simulation of fluid and structure or sound field coupled problems
・High energy and real gaseous simulation of supersonic flow
We conducted the simulations above with practical features and phenomena simulations in 10,000,000~1,000,000,000 grids order. And we are now advancing the validations of simulations for various practical problems in order to apply them for the digital engineering in the future.
The simulation software whose developing and validation we are related to
- FrontFlow/red: Multi-physics fluid simulation software
Development of this program was conducted as one of "Developing tactical innovative simulation software program" , which was a research and development program for constructing the basis of the next generation IT. Thanks to many official grants, joint researches, and cooperations, we, CFML, played a major role in the development, validation, and spreading FrontFlow/red. These days, the software is made public on the homepages of Hokkaido University and RIKEN.
- RG-FaSTAR: High-enthalpy flow solver
RG-FaSTAR is a software which transport effect, thermal chemistry, and the reaction model in the high-temperature region as real gas effects are added to FaSTAR. It can deal with the analysis of high-enthalpy flow which appears in the reentry process of spacecraft. It is used in the research and education to investigate the behavior of high-enthalpy fluid which appears around the spacecraft when it reentries in the Earth's atmosphere. And the confirmation of its performance is conducted by large-scale computation with large computational resources, for example, KEI (京).
- Arcflow/Arcwave: Plasma flow and electromagnetic wave analysis solver
Arcflow/Arcwave contains the electromagnetic wave analysis solver which is based on FD2TD method. Combining with RG-FaSTAR, We can conduct the prediction of reentry blackout.
- The analysis method for the reactive fluid with the detailed chemical reaction mechanism
We research and develop the high efficient numerical analysis method in order to model the interaction of detail chemical reaction and fluid dynamics in the combustion phenomena. We developed the fast explicit time integration method for the equation of chemical reaction and the chemical species bundle method for transport coefficient of multi-species. We could make the calculation faster than the ordinary method by 2-3 digits thanks to these two methods. In order to extend the range of application of it, we research the sub-grid scale models which are proper to the reaction term which is based on Alenius expression.