add steady case representation
add steady case representation

li12242/NDG-FEM,li12242/NDG-FEM,li12242/NDGFEM_Matlab,li12242/NDG-FEM,li12242/NDGFEM_Matlab,li12242/NDGFEM_Matlab,li12242/NDGFEM_Matlab,li12242/NDG-FEM