I have already done that, so I tried proximity or hard sizing function on those surfaces. But wrapping still couldn't capture the gap, it just generated a finer mesh for those parts. The gap is about 40 mm, while proximity (min= 5mm, max, 50 mm) and hard (min=5 mm) did not work. The gap/cell size ratio was around 8. 
Should I set the local sizing even smaller?
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