Two-fluid modeling of heat transfer in flows of dense suspensions

TL;DR

This paper introduces a two-fluid model for heat transfer in dense suspensions, capturing particle migration effects driven by shear and thermal gradients, validated through simulations of Couette flow.

Contribution

The paper develops a novel two-fluid model with closure relations for heat transfer, incorporating thermo-rheological migration effects validated against experimental data.

Findings

Particle migration is driven by shear and thermal gradients.

The thermo-rheological migration force explains observed particle behavior.

Heat transfer coefficient is influenced by both shear-induced and thermo-rheological migration.

Abstract

We develop a two-fluid model (TFM) for heat transfer in dense non-Brownian suspensions. Specifically, we propose closure relations for the inter-phase heat transfer coefficient and the thermal diffusivity of the particle phase based on calibration against experimental data. The model is then employed to simulate non-isothermal flow in an annular Couette cell. We find that, when the shear rate is controlled by the rotation of the inner cylinder, both the shear and thermal gradients are responsible for particle migration. Within the TFM framework, we identify the origin and functional form of a "thermo-rheological" migration force that rationalizes our observations. Furthermore, we apply our model to flow in eccentric Couette cells. Our simulations reveal that the system's heat transfer coefficient is affected by both the classic shear-induced migration of particles and the newly identified thermo-rheological migration effect.