clumping

Clumping is the tendency of individual units to aggregate into clusters or clumps. The units can be particles, cells, organisms, or molecules. Clumping is distinguished from uniform dispersion by the presence of localized concentrations and from complete cohesion only when clumps form. It results from interactions that promote adhesion or attraction, and it can be driven by physics, chemistry, and biology, as well as environmental conditions.

In materials science and engineering, clumping is commonly described as coagulation or flocculation of suspended particles. Adhesive forces, ionic strength, pH, and additives cause particles to stick together, forming flocs that can be separated by sedimentation or filtration. In powder handling, moisture-induced clumping reduces flow and handling efficiency; anti-caking agents and proper storage are used to prevent this.

In ecology and population biology, clumping (or aggregated distribution) is a common pattern in which individuals are clustered in patches rather than evenly spread. Resource heterogeneity, social behavior, and mating systems produce clumps. Researchers quantify clumping with statistics such as the variance-to-mean ratio, Morisita's index, and Lloyd's index of patchiness, which help distinguish clumped from random or uniform distributions.

In microbiology and medicine, clumping can refer to cells sticking together, forming biofilms, or platelets clumping in blood samples, which can interfere with diagnosis or treatment. Clumping can be adaptive, aiding survival and resource capture, but it can also cause problems in industrial processes and clinical testing.