MHD & EHD: Electric Field Effect on Nanofluid Heat Transfer

Electric Field Effect on Nanofluid Heat Transfer (EHD) — ANSYS Fluent CFD Simulation Training

This project investigates the flow of a nanofluid through a bumpy channel under the influence of an applied electric field, using ANSYS Fluent. The flow is treated as steady-state and modeled using a single-phase approach, with the nanofluid's thermophysical properties—density, viscosity, specific heat, thermal conductivity, and electrical conductivity—adjusted to reflect the presence of the nanoparticles. The applied electric field alters the fluid's flow behavior, which in turn enhances heat transfer. The surface-averaged temperature of the nanofluid is 300 K at the inlet and 301.926 K at the outlet.

Geometry and Mesh

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

Setup and Assumptions

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

The 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, turbulence intensity of 5%, 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 using second-order schemes, momentum uses second-order upwind, and turbulent kinetic energy and dissipation rate use first-order upwind. Hybrid initialization is used to start the solution.

Results and Discussion

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

Comparing the two cases highlights the effect 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.