
Turbulence enhances the aggregation and growth of particles like raindrops or blood clots.Turbulent coagulation is a process where turbulence in a fluid enhances the rate at which small particles collide and stick together, forming larger aggregates. This mechanism is crucial in many natural and industrial settings, from the formation of raindrops in clouds to the aggregation of blood clots in arteries. In a turbulent flow, particles are carried by chaotic eddies, which increases their relative velocities and collision frequencies, thereby accelerating the coagulation process compared to still or laminar conditions.
The study of turbulent coagulation began in the mid-20th century, with foundational work by Russian scientist A. N. Kolmogorov on turbulence and later by S. K. Friedlander and others who applied these ideas to aerosol and cloud physics in the 1950s and 1960s.
The process relies on the statistical properties of turbulence, such as the distribution of velocity fluctuations and the energy dissipation rate. Particles in a turbulent flow experience random relative motions due to the turbulent eddies. When two particles come into close proximity, they may collide and, if the forces holding them together (like van der Waals forces or surface tension) are strong enough, they stick. The efficiency of this process depends on the particle size, density, and the intensity of turbulence, which can be characterized by the Kolmogorov microscale—the smallest scale of turbulent motion.
Turbulent coagulation is used in weather prediction models to simulate rain formation, in industrial processes like spray drying and flocculation in water treatment, and in biomedical research to understand thrombus formation in blood flow.
Recent research has shown that in some conditions, turbulence can actually inhibit the growth of raindrops by breaking them apart, challenging the long-held assumption that turbulence always enhances coagulation.
| B | variable | Bayes factor — bayes factor |
| D_k | variable | k-th data point — data |
| H_1 | variable | alternative hypothesis — hypothesis |
| H_0 | variable | null hypothesis — hypothesis |
| N | variable | number of data points — sample size |
| ∏ | operator | multiplication of terms for k=1 to N — product operator |
| v_{\rm term} | variable | Terminal outflow velocity — velocity metre per second |
| \dot{m} | variable | Mass accretion rate — mass accretion rate kilogram per second |
























