[war_mad]

Hi,

I am currently working on a steady-state heat transfer simulation using Fluent, focusing on a two-phase system involving oil and air. The setup includes a heated copper solid plate with oil injection for cooling, where approximately 20% of the metal is in contact with the oil jet stream, and the remaining part is exposed to surrounding air.

Here are some key details of my simulation:

• Computational domain with one velocity input (only oil injection, no air) and one pressure output (oil and air escape, backflow of air is seen during simulation. But backflow of oil is not allowed).
• Adiabatic walls and coupled solid-fluid contact surfaces.
• Metal geometry defined as a constant heat source.
• Multiphase model using VOF with Implicit formulation.
• Turbulent model: K-omega SST.
• Steady-state simulation with pseudo-time stepping and enabled high-order term relaxation.
• Mesh properties: Orthogonal quality (2.3), aspect ratio (90), 10 boundary layers at the thermal boundary layer, Max y+ value around 1.5, average y+ below 1.

While the temperature values from the simulation match well with the experimental data, I am facing a significant issue with the heat transfer coefficient. The experimental values are around 800, but the simulation results yield a much lower value of around 50. I also get unrealistic surface heat flux values in areas where the metal is in contact with air, with many regions showing zero or negative values. The average temperature difference between the fluid and the metal is around 10 degrees.

I would greatly appreciate any insights, suggestions, or recommendations to improve the accuracy of the heat transfer coefficient and surface heat flux values in my simulation.

Thank you in advance.

Waruna