The ornamental design for a fluid application apparatus, as shown and described.
FIG. 1 is a perspective view of a fluid application apparatus showing my new design;
FIG. 2 is an alternative perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a side elevation view thereof;
FIG, 6 is an opposite side elevation view thereof; and,
FIG. 7 is a top plan view thereof.
The broken lines showing the unshaded region of the fluid application apparatus are for environmental purposes only and form no part of the claimed design.