Hi, I am attempting to run a flow simulation for a CD nozzle with a pitot tube on the surface of the tunnel at supersonic conditions however the mesh inside the tube will not capture the fluid cells. 

i have found that if i do a 0.010" diameter tube, the mesh will capture but if I do anything smaller it does not work. In the attached photos is a picture of the tube which is 0.00445" OD, the mesh that was generated, and the mesh settings. I've reduced the minimum gap size down to 0.0001 and it did not help. if i move the tube off of the wall then the mesh will capture. Any help with what setting will allow me to solve with the tube on the wall will be much appreciated.

Thanks,

Ron