I have a time-varying flow solver programmed using FEniCS library in Python. I have a script that creates the time-varying flow profile on the inlet flow surface of the domain. I can write that profile (function of space and time) into a vtk/hdf/xdmf file. However, I don't know how to use this external file to set-up the Dirichlet BC for the inlet boundary surface. Any help or code examples in this regard will be helpful.