– Amount of extra space to leave around smoke, measured in voxels. With very fast-moving smoke larger margins may be required to prevent the smoke from being cut off by the adaptive boundary.

– Attention: this will increase the computational time.

– Note how the adaptive domain stay far from the smoke until reaching the domain maximum size:

– The behavior of the smokes are different expecially at the beginning, during the adaptive domain expansion:

Blender Smoke Domain Margin