Help with Ansys Meshing for fluent overset grid
 

Hello all, I wish to carry out overset meshing analysis for a body moving through a cylindrical channel in 3D with a T junction as inlet (Length of Cylindrical channel>>Inlet junction pipe and T junction location is in beginning). Now the distance between the object and channel's walls are close to 1 cm only and in overset meshing there needs to be at least 4 cells between two solid walls in the geometry. If we follow it, since this method comprises of channel and object meshes separately (with object mesh having a fluid boundary for the overset interface creation in the analysis).
Now my question is, I tried and succeeded in eliminating the overset errors of orphan cells, donor etc. by creating inflation layers with total thickness and number of layers. Although the residuals are converging, the mesh motion is not converging at each time step. I am pretty sure that this is owing to large aspect ratio of 45 (>15) in the background mesh of the channel. I want to improve the simulations by giving highly fine tetrahedral cells in the 1 cm gap region between the body and channel (both are concentric) instead of inflation layers. Only tetrahedral mesh works for this geometry and giving a very low maximum size in the order of the gap between the solid walls in ansys mesh sizing simply shoots up total count.
I saw a wonderful demonstration of overset meshing in the below video, whose screenshot I am attaching as image.
https://www.youtube.com/watch?v=ugKxL4NWN3g
I wish to have a similar kind of grid in our circular channel, except that this sizing is not limited to a small portion of the total length, but must be thoroughly from the start to end of the pipe as object moves full length of pipe. And the highly fine sizing needs to be between the enclosure and the channel walls; not in the region of body. :confused: I could find very scarce resources for this issue. Your aid is very valuable.
Thank you