GPU-accelerated transient thermo-hydraulic simulation of weakly compressible restart flow of a non-Newtonian fluid in a long-buried hot oil pipeline

For the complex transient thermo-hydraulic restart process of a long-buried hot oil pipeline, it takes a long time to solve the restart simulation model, which cannot meet the requirements of rapid restart prediction and assessment. The modern GPU is specialized for compute-intensive and massively parallel computation, and it has great potential to accelerate transient thermo-hydraulic restart simulation. According to the computational characteristics of restart model solutions, four types of GPU parallel strategies, from the mapping of grids to the convergence judgment of the discrete equation solution, are combined to accelerate the whole process of a transient thermo-hydraulic restart simulation. The results indicate that the total computation time of the transient thermo-hydraulic simulation is reduced from 185.4 min to 8.8 min, corresponding to an acceleration rate of 21.1, which exhibits a good acceleration effect for a single GPU and is beneficial to the rapid assessment of restart schemes. Based on the GPU-accelerated numerical results, the complex transient thermo-hydraulic restart process with the changing soil temperature field, the non-Newtonian thixotropic behavior of crude oil and flow pattern evolution, is investigated. The analysis reveals that the dominant influencing factors of the restart process vary with the restart time, and the flow pattern evolution plays an important role in the thermo-hydraulic characteristics of the restart process.