Extending the cell-based smoothed finite element method into strongly coupled fluid-thermal-structure interaction

This work generalizes the cell-based smoothed finite element method (CS-FEM) into fluid-thermal-structure interaction (FTSI) analysis under the arbitrary Lagrangian-Eulerian description. The thermal buoyancy is included with the incompressible Navier-Stokes equations through the Boussinesq approximation. The combined fluid flow and energy equations are solved by a smoothed characteristics-based split algorithm that incorporates equal low-order interpolations for the three primitive variables. The structural motions involving both oscillating rigid and flexible bodies are advanced by the generalized-alpha method. Moreover, the nonlinear elastodynamics equations discretized with the CS-FEM are linearized by the modified Newton-Raphson method. An efficient two-level mesh updating scheme is subsequently discussed to account for large structural displacement and finite solid deformation. The cell-based smoothing concept is then adopted to evaluate fluid forces acting on the immersed structure. The smoothed FTSI system is iteratively solved by the block-Gauss-Seidel procedure. Transient FTSI examples are tested to demonstrate the effectiveness and robustness of the CS-FEM.