Reply To: Effect of Surface Area in Convection in Steady State Thermal Simulation

[Hakim Dina Anjum]

It is absolutely okay. I appreciate the prompt clarification of the confusion, and all the insights on the flux parallel conditions and the intuitive review in the previous response. I myself am a newbie in the field and am finding the forum pretty supportive.

I want to clarify that the convection coefficient (h) was not one constant value over the surface. I did not input one constant value of h over the surface, as I do not know the temperature of that surface (which is the output of this simulation) that is required to calculate h.

Instead, I calculated the values of h for 42 temperature values ranging from -1C (minimum T of the setup, the temperature of the inside face of the refrigerator door) and 32C (maximum T of the setup, the ambient temperature) using the following equations, and input a tabular data of h vs Ts in the field of Convection BC.

So, as the geometry is not of uniform thickness (the actual model I showed in my second reply), the outer surface temperature will vary, and ANSYS will solve the model using different values of h for different nodes, according to their corresponding surface temperature.

Again, the L value used in calculation of h is of the actual refrigerator door, not of the reduced (upper third  portion of the refrigerator door) model. My understanding behind it is that I only reduced the geometry for computational efficiency. The surface of that reduced portion would've had the same effect of h if the whole model was taken. So h should account for the whole surface. 

This was my overall understanding of the simulation. I would like to understand if there's anything noticably incorrect in my approach.

Having said all that, I did not understand what you meant about using  'the average' value of h, but feel free to skip it if it not related to the updated contex anymore. 

Lastly, I would prefer Mechanical over Fluent or CFX as a conduction based solver seems sufficient enough in simulating such simpler cases of heat transfer where we do not require to model the fluid flow. The aim of this simulation is to simply find out the temperature on the outer face of a refrigerator door. The geometry might be complex but the overall setup here is pretty simple. As ANSYS Mechanical provides enough flexibilities in the input of h, I definitely want to put those to use before, if not rather than, opting for a computationally more expensive CFD solver.

Once again, I appreciate the insightful discussions and support. Thank you for your enormous patience.