Flow of a material refers to:

The term flow, rather than creep, has generally been used in dentistry to describe the rheology of amorphous materials. Creep is defined as the time-dependent plastic strain of a material under a static load or constant stress. The creep or flow is measured as the percentage decrease in length that occurs under these testing conditions. Key Concept: Flow of a material refers to continued change of the material under a given load. Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 33, 34