在OpenFOAM4.1及以前版本，pointDisplacement的边界条件中包含sixDOFRigidBodyDisplacement，从5.0版本开始删除了这个边界条件。可以直接通过dynamicMeshDict进行设置，具体原因可以参见链接

These legacy boundary conditions are no longer needed and have been superseded
by the more flexible sixDoFRigidBodyMotion and rigidBodyMotion solvers.  See tutorials:

incompressible/pimpleDyMFoam/wingMotion/wingMotion2D_pimpleDyMFoam
multiphase/interDyMFoam/RAS/DTCHull
multiphase/interDyMFoam/RAS/floatingObject