Bismihi Ta'ala

1. If the water doesn't flow from the wound itself then wudu will not brake.

2. If the water comes right to the top of the wound and exceeds the wound but doesn't move either side, then there is a difference of opinion amongst the Jurists. The most sound opinion is that wudhu will not brake in this situation.

3. However, if the water passes the surface of the wound and flows on either side then this will brake the wudhu.

And Allah knows best.