Fluid-solid conjugate heat transfer modelling using weakly compressible smoothed particle hydrodynamics

To date, the Smoothed Particle Hydrodynamics (SPH) method which is mesh-less and fully Lagrangian in nature has been mainly applied in solving solid heat conduction problem and flow convection problem separately. In the current work, we have implemented the Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method to solve internal flow problem involving fluid-solid Conjugate Heat Transfer (CHT). In order to ensure heat flux continuity across the interface separating two different materials, the harmonic mean value of thermal conductivities was adopted when modelling the heat transfer between fluid and solid bodies. On the modelling of non-isothermal hydrodynamically fully-developed channel flow, the Dirichlet inlet temperature boundary condition was implemented without having to build a separate temperature reset zone as proposed in the open literature. From the current study, we have found that the particle shifting algorithm is efficient to address the tensile instability problem encountered when simulating flow at high Reynolds number. The WCSPH results were compared against the established analytical and numerical solutions and good agreement was found. The idea of extending the WCSPH method to simulate the flow and heat transfer in parallel-flow and counter-flow heat exchangers was pursued in the current study as well

Computer Simulation of Hemodynamic Changes After Right Lobectomy in a Liver with Intrahepatic Portal Vein Aneurysm

Intrahepatic portal vein aneurysm is rare and its natural history is unknown. A 22-year-old healthy man, who wished to donate part of his liver to his diseased father, was incidentally diagnosed to have an intrahepatic portal vein aneurysm. The surgical decision of performing live donor hepatectomy for such a patient is normally difficult. We combined modern imaging reconstruction technologies with scientific computing as a new modality to foresee the risks of surgical complications. Methods: Cross-sectional computed tomography images were used to reconstruct the three-dimensional image of portal vein distribution using the 3D-Doctor v3.5 software. The reconstructed images were further employed to generate surface and interior meshes with CFX software. Simulated hemodynamic changes in velocity, pressure, and wall stress were determined for the right lobectomy case pre- and postoperatively Results: The simulation results indicated that aneurismal pressure would be elevated significantly to 12.03 mmHg after operation. The left segmental portal venous blood flow would increase from 2.95- to 4.25-fold. The area near the branch point of one left segmental portal vein, which supplies blood to liver segment 4, and the portal vein aneurysm would endure high shear stress gradient. The resulting elevated aneurismal pressure may cause the thin wall to enlarge and rupture, while the high shear stress gradient would lead to vascular endothelial cell injury. Living donor surgery was not recommended hemodynamically based on the simulated results. Conclusion: Scientific computing and modern imaging technologies can be applied together to aid surgeons to make the best decision in difficult clinical situations