When importing boundary conditions from Nek5000 without specifying a boundaryTypeMap in the parameter file, boundary IDs are typically not present—except when the mesh is imported using one of the available mesh converters. In the absence of boundary IDs, we apply a heuristic approach that assigns IDs by mapping each boundary type to a unique identifier. While this method works well in most cases, it may lead to incorrect mappings in configurations where the number of boundary conditions differs between velocity and scalar fields.
When importing boundary conditions from Nek5000, only temperature can be defined on a t-mesh.