Does having skin necrosis after Tummy Tuck operation make swelling last longer? (photo)

Yes, It's common to have swelling after a tummy tucka and specially if your wound hasn't healed yet. First take care of the wound and then the swelling will go down 

Definitely it is very common to observe the swelling process to remain or be even more severe after any type of complications, specially incision complications. Swelling is a natural part of the healing process, and yours is now focus on healing the open wound, so, just be patient. Your open wound looks clean and healthy, so it will be closed in no timeBe encouraged.Dr. Cardenas

Most likely your swelling is just related to delayed healing, and the inflammation that goes along with that condition.  Once the wound is closed, then the swelling should start improving, so you have a little way to go.With an open wound, it would be uncommon to have swellling related to a fluid pocket or seroma.  Make sure your surgeon has considered this potential problem.  An ultrasound scan may be indicated.In most cases this is just post-op inflammation that will slowly resolve.Be patient, and good luck to you!  You still can have a nice result.