Simplest answer is to point you at the Super Bug's inlet, where there's a gap between the top of the inlet and the LEX, with a shaped bit of structure a bit of the way back that smoothly close out the gap. You'll see similar bits between the F-14 or F-15 inlets and their respective fuselages. The F-35 was the first design with a diverter-less inlet and there shaping move the boundary layer away from the inlet; the J-31 looks to use the same approach as does the J-10B.