IMMERSED BOUNDARY-SIMPLIFIED THERMAL LATTICE BOLTZMANN METHOD FOR FLUID-STRUCTURE INTERACTION PROBLEM WITH HEAT TRANSFER AND ITS APPLICATION

An Immersed boundary-simplified thermal lattice Boltzmann method(IB-STLBM) for fluid-structure interaction problem with heat transfer is developed in this work. In the IB-STLBM, an effective simplified thermal lattice Boltzmann method without the evolution of distribution is used for the intermediate flow field. Different from the stander thermal lattice Boltzmann method, STLBM directly updates the macroscopic variables instead of the distribution functions, which offers several distinct benefits：lower cost in virtual memories, simpler implementation of physical boundary condition and higher numerical stability. In addition, from the mesoscopic view, the existence of solid boundary in the field is considered as an interference of system, which breaks the original equilibrium state of fluid particle, and a non-equilibrium state occurs on the fluid-structure interaction physics boundary. On this basis, in the present IB-STLBM, fluid-structural interaction duo to Immersed boundary appearance in the fluid can be expressed by the non-equilibrium distribution function, which is calculated by the popular non-equilibrium bounce-back boundary condition of the LBM. Hence, the solution procedure of present IB-STLBM can satisfy the non-slip boundary by a simpler way. Numerical experiments for the forced convection over a stationary heated circular cylinder and natural convection in a square cavity with a circle particle are presented to verify the stability, the capability and the flexibility of IB-STLBM for fluid-structure interaction problem with heat transfer. In the case of a stationary heated circular cylinder, quantitative and qualitative comparisons are carried out with previous study. The results of the drag coefficient and the avenge Nusselt numbers on the cylinder are in accordance with the results of previous study. From the case of natural convection in a square cavity with a circle particle, some interesting phenomena can be found. First, the temperature field is clearly stirred by the suspended particle. Second, the temporal trajectories of the particle exhibited regular changes. Third, the particle enhances heat transfer and the average Nusselt numbers periodically oscillate with time.