title: Temperature gradients drive radial fluid flow in Petri dishes and multiwell plates.
abstract: Liquid in a Petri dish spontaneously circulates in a radial pattern, even when the dish is at rest. These fluid flows have been observed and utilized for biological research, but their origins have not been well-studied. Here we used particle-tracking to measure velocities of radial fluid flows, which are shown to be linked to evaporation. Infrared thermal imaging was used to identify thermal gradients at the air-liquid interface and at the bottom of the dish. Two-color ratiometric fluorescence confocal imaging was used to measure thermal gradients in the vertical direction within the fluid. A finite-element model of the fluid, incorporating the measured temperature profiles, shows that buoyancy forces are sufficient to produce flows consistent with the measured particle velocity results. Such flows may arise in other dish or plate formats, and may impact biological research in positive or negative ways.
authors.affiliation: Department of Chemical and Biological Engineering, Systems Biology Theme, Wisconsin Institute for Discovery, University of Wisconsin - Madison, 330 N Orchard Street, Madison, WI 53715, United States.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Lindsay
authors.affiliation: Department of Chemical and Biological Engineering, Systems Biology Theme, Wisconsin Institute for Discovery, University of Wisconsin - Madison, 330 N Orchard Street, Madison, WI 53715, United States.
authors.forename: John
authors.initials: J
authors.lastname: Yin
keywords: COMSOL; Petri dish; Transport phenomena and fluid mechanics: natural convection; computational fluid dynamics; confocal microscopy; particle tracking; thermal imaging; virus comet assay