[MAHESH9966]

Hello everyone,
I am new to multiphase flow simulations and looking for guidance on where to start for simulating oil-cooled electric motors. My primary goal is to analyze the heat transfer and fluid dynamics of oil cooling inside a rotating electric motor.
My Background:

• I have experience with CFD software, specifically ANSYS Fluent.
• I understand single-phase flow but have limited exposure to multiphase simulations.
• My focus is on oil flow behavior and heat dissipation in rotating components.

Challenges & What I’ve Tried:

• I want to learn multiphase simulation concepts but have struggled to find relevant resources.
• I have watched some YouTube lectures on multiphase flow, but most of them are focused on chemical engineering applications, which do not fully address my case.
• I am unsure which multiphase models (VOF, Eulerian, Lagrangian, etc.) are best suited for this type of simulation.

My Questions:

1. What is the best approach to modeling oil cooling in rotating electric motors?
2. Are there any recommended tutorials, case studies, or research papers related to this type of problem?
3. Which multiphase models and turbulence models should I consider for oil flow and heat transfer?
4. What are the best practices to ensure accuracy and stability in such simulations?

Any guidance, references, or shared experiences would be greatly appreciated. Thank you in advance for your help

[MKuhn]

Hi Kadari,
I do not see the multiphase issue in your oil cooling problem. Normally there shoud be no evaporation and even if the oil consits of serveral components, i would handle it as a pseudo pure fluid. And, first use the default turbulance model.

[MAHESH9966]

Originally Posted by MKuhn

Hi Kadari,
I do not see the multiphase issue in your oil cooling problem. Normally there shoud be no evaporation and even if the oil consits of serveral components, i would handle it as a pseudo pure fluid. And, first use the default turbulance model.

Thank you for your kind reply. It means a lot to me.


I have some knowledge of turbulence models but need clarification on how to accurately represent oil spray cooling. Specifically, I would like to understand:

1. Modeling Approach:
   • Is the workflow for oil spray cooling similar to air cooling techniques?
   • Should I define the entire motor interior as an oil-filled domain? (This seems unrealistic, as excess oil may increase drag and reduce performance.)
2. Oil-Air Interactions:
   • Since oil cooling relies on spray mechanisms, I assume there is significant oil-air interaction.
   • What is the best way to model this interaction in Fluent? Should I use the Discrete Phase Model (DPM) for oil droplets along with a wall-film model to account for heat transfer?
   • Would VOF or Mixture models be a better choice in certain cases?
3. Workflow Recommendations:
   • What are the key steps to set up such a simulation effectively?
   • Are there specific best practices for defining boundary conditions, injection properties, and turbulence models?

Your insights would be highly valuable in helping me refine my approach. I appreciate your time and expertise!

[MKuhn]

Ok, I thougt it is a flooded oil cooling. For spray cooling indeed you need a multiphase model, I would start with DPM. I don't have much experience with multiphase models and can't help you much here.