I am working on a simple ANSYS Fluent (16.2) multiphase flow simulation and am having trouble meshing the surfaces. The geometry is a larger straight tube with a smaller straight tube inside the larger one along the same axis with one end of each tube sharing the same plane. When I attempt to mesh it using meshing settings like the bifurcated artery Cornell tutorial ( https://confluence.cornell.edu/display/SIMULATION/3D+Bifurcating+Artery+-+Mesh) i.e. setting a sizing element size & inflation region similar to the example. I get a meshing error "One or more non-sweepable bodies have sweep method controls and cannot be swept." This appears to be because the 2 ends have a difference due to the overlap of the smaller tube on one end because sweeping seems to want to copy the mesh from one end onto the other based on my understanding of mesh sweeping after reviewing this page (https://www.sharcnet.ca/Software/Ansys/16.2.3/en-us/help/wb_msh/ds_Mesh_Sweeping.html). Does anyone have any suggestions on how to mesh this? I intend on having the the ring around the smaller tube defined as an inlet for one fluid type and the smaller tube an inlet for a 2nd fluid with the mixture coming out the far end. See attached model rendering.