Research On The Key Technologies Of The High Performance Computing With HopeFOAM

Driven by high performance computing(HPC)technology,numerical simulation has gradually become the third paradigm of scientific research after physics experiment and theoretical analysis.As a typical representative of simulation,computational fluid dynamics(CFD)simulation has gained a great deal of attention in academia and industry due to its low cost,high flexibility and easy repetition.CFD is a comprehensive interdisciplinary discipline that integrates physics / chemistry / biology,mathematics and computer science,its complete simulation process requires the participation and collaboration of multi-domain expert users.As a result,most of the CFD simulations are based on a generic framework.Since the framework includes complex processes such as modeling,discretization and solution,it poses a series of difficulties and challenges in terms of design and development,configuration and use,optimization and analysis.This paper focuses on the four typical problems of CFD simulation framework: difficult to design,difficult to use,difficult to optimize and difficult to analyze.Based on the HopeFOAM simulation framework,the key technologies of efficient parallel numerical simulation are studied.The main work and innovations are as follows:· A numerical module is designed and implemented in HopeFOAM based on the PETSc library(Section 2)In this paper,the numerical solution requirements of the HopeFOAM simulation framework are analyzed in depth.An overall framework of the efficient numerical solution module is designed based on the PETSc library,which fully considers the support of HopeFOAM for many discretization schemes such as low-order FVM and high-order DGM.A complete numerical solution module is implemented based on the designed numerical solution framework,the matrix assembly process of the numerical solution module is optimized according to the structural characteristics of the linear system of equations,and the overall efficiency of the numerical solution module is greatly improved.The correctness and validity of the realized PETScbased numerical solution module are verified based on the typical Benchmark cases in the CFD domain.The research results improve the numerical solution efficiency of the platform and further improve the effectiveness of the platform.· A mesh-degree independence theory is proposed and applied in HopeFOAM framework(Section 3)After extending and abstracting the traditional mesh independence theory for loworder simulation,this paper proposes a more generalized mesh-degree independence theory.The related concepts in this theory are defined in detail,such as mesh-degree configuration pair,mesh-degree-independent configuration pair,and optimal mesh-degree-independent configuration pair.The complete flow of application of the theory in actual simulation and the key technologies required are given.The typical CFD Benchmark cases validate the theory in guiding the configuration of grid spacing and discretization orders in the simulation.The research results provide theoretical guidance for the optimal parameter configuration of high-order simulation and improve the usability of the related simulation platform.· The parallel scalability of HopeFOAM is highly optimized(Section 4)In this paper,the performance bottleneck based on HopeFOAM framework is analyzed in depth,and the communication overhead in the simulation process is optimized by redundant communication identification and elimination.After deeply analyzing PCG algorithm,the communication hidden in numerical solution process is realized by rearrangement technique.Through the non-blocking collection communication in PCG algorithm,the overlap of calculation and communication is further increased.Verification and validation of the optimization technologies are conducted based on the Benchmark cases in the CFD field.The results show that the overall simulation performance is improved by more than 60% and the scalability is increased by about 3 times.This research offers the possibility of large-scale framework-based parallel CFD simulation and improves the practicability of the relevant simulation platform.· A multi-user performance analysis tool is designed and implemented in HopeFOAM(Section 5)After analyzing the situation and needs of the performance analysis of HopeFOAM simulation framework,this paper designs a comprehensive performance analysis framework for multi-domain users.The functional modules and performance data of the performance analysis framework for multi-domain users are designed in detail.Based on the designed framework,functional modules and performance data,HopeFOAM implements a lightweight performance analysis tool that supports both dynamic and static performance analysis,and includes various forms of crossvisualization modes such as images and tables.Typical CFD Benchmark cases validated the capabilities and cost of the performance analysis tool,which showed that the overall cost of the tool was within 5%.The research results provide significant support for the performance optimization of CFD simulation,thereby improving the reliability of the related simulation platform.