Electric Field Effect on Nanofluid Heat Transfer

Description

This project investigates the flow of a nanofluid through a bumpy channel under the influence of an applied electric field, using ANSYS Fluent. The study centers on the nanofluid itself: it is treated as steady-state and modeled with a single-phase approach, in which the fluid's thermophysical properties — density, viscosity, specific heat, thermal conductivity, and electrical conductivity — are adjusted to reflect the presence of the suspended nanoparticles. This modified-property treatment is the defining feature of nanofluid modeling, allowing the enhanced heat-transfer behavior of the particle-laden fluid to be captured without simulating each particle individually. The applied electric field alters the fluid's flow behavior, which in turn enhances the heat transfer. The surface-averaged temperature of the nanofluid rises from 300 K at the inlet to 301.926 K at the outlet.

Geometry & Mesh

The fluid domain was created in Design Modeler, and the mesh was generated in ANSYS Meshing. The mesh is unstructured, with a total of 17,640 elements.

Methodology

The simulation uses a pressure-based solver under steady-state conditions, with gravitational effects neglected. The energy equation is active, and turbulence is modeled using the realizable k-epsilon model with standard wall functions.

The working fluid is defined as a modified water-based nanofluid with a density of 998.2 kg/m³, specific heat of 4182 J/kg·K, thermal conductivity of 0.6 W/m·K, viscosity of 0.001003 kg/m·s, constant UDS diffusivity, electrical conductivity of 1,000,000 S/m, and a magnetic permeability of 1.257 × 10⁻⁶. At the inlet, a velocity inlet condition is applied with a velocity magnitude of 1 m/s, a turbulence intensity of 5%, a turbulent viscosity ratio of 10, and a temperature of 300 K. The outer solid wall is held at a fixed temperature of 340 K.

The SIMPLE scheme handles pressure-velocity coupling, with least-squares cell-based gradients. Pressure and energy are discretized with second-order schemes, momentum with second-order upwind, and the turbulent kinetic energy and dissipation rate with first-order upwind. Hybrid initialization is used to start the solution.

Conclusion

With the electric field applied, the average outlet temperature of the nanofluid reaches 301.926 K, compared with 300 K at the inlet, corresponding to a heat flux of 72,474.1 W. Without the electric field, the outlet temperature is slightly lower at 301.92 K.

Comparing the two cases highlights the influence of the electric field: its application raises the outlet temperature by approximately 0.04 K and increases the heat transfer rate to the nanofluid by about 54 W/m². The result demonstrates how coupling an electric field with a modified-property nanofluid model can be used to enhance convective heat transfer — a promising strategy for thermal-management applications where nanofluids are employed as high-performance working fluids.