Thermally fully developed pipe flows of active liquids
Year: 2025
Type: article
Abstract: Active matter laden active liquids define a unique class of liquids, whose dynamics can be captured only by appropriately including the contribution of active matter induced stresses in the relevant fluid flows equations. Such a consideration has led to identifying very rich fluid flow phenomena for a variety of active-flow scenarios. In this paper, we develop analytical solutions for studying the effect of a background active fluid flow in the temperature distribution and the Nusselt number in a thermally fully developed pipe flow in the presence of constant surface heat flux. Specifically, we consider the flow of an active liquid consisting of active particles demonstrating vortex defects: under such circumstances, in presence of an axial gradient in activity, there occurs an induced pressure-driven flow in a pipe that has a profile different from the Hagen-Poiseuille flow profile in non-active pressure-driven (due to externally imposed pressure gradient) flow. We find that the Nusselt number for the case of the background active flow is 3.83, which is smaller than the classical value of 4.36 observed for the background pressure-driven flow (with constant heat flux). We justify this decrease by noting that for the case where the activity gradient (for active flows) is identical to the pressure gradient (for non-active pressure-driven flows), the overall flow strength is smaller for the active flows: such reduced flow strength causes a reduced convective heat transfer triggering a decrease in the Nusselt number for the case of the background active flows. This reduced convective heat transfer also causes a smaller temperature away from the wall (for the case where the wall temperature is greater than the mean temperature) for the case of the background active flows.
Source: Physics of Fluids
DOI: 10.1063/5.0258996
Author: Siddhartha Das
Institution: University of Maryland, College Park
Language: English
Topic: Micro and Nano Robotics
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4408164562