I am generating hexahedral mesh in ANSYS ICEM CFD 16.1 for flow analysis in ventilation air duct. My pre-mesh is not looking alright - mesh only cover a larger section of the geometry (see below images). I used the native 3D hexa meshing approach i.e. blocking, association, application of mesh parameters (Curve Mesh Setup) with the blocking carried out with a T-shaped topology. I also tried creating O-grid Splitting method, no improvement. Below are the images of my pre-mesh (3D, X-Z view, Y-Z and X-Y respectively). Kindly assist me with ideas on getting a proper pre-mesh for this geometry.
Many thanks in anticipation.