Learning Forum

[PipMin]

Hi everyone,

I'm doing a project which aims to study the cooling properties of a disc brake. My model is a stationary one, which a fluid temperature of 20°C and a disc brake temperature of 300°C. The fluid domain is rotating in speed range from 200 to 2000 rpm. I studied only a portion of the disc as I can use the periodicity. Also, I am using a Total energy approach.

I have two questions which I don't understand:

1) I read about to set a Tbulk in the expert parameters. I don't know if I have to do it or not, some papers say yes but a lot of them don't mention it. Shall I have to set a Tbulk? Why?

2) As in the real life the convective heat transfer coefficient is the dominant one, how can I extrapolate it from my CFD simulation? I saw that in CFD post everyone use wall heat transfer coefficient contours but I really can't understand why this is comparable with the convective heat transfer coefficient obtained from experimental work.

This is my thesis project, so it would be great if someone can help me!

Cheers 

[DrAmine]

1/When the Heat Transfer Coefficient (HTC) is computed for a temperature specified wall, by default a near-wall fluid temperature is used for a temperature scale. However, for consistency with traditional 1D analyses, you may want to enter a reference bulk temperature to compute the HTC. Tbulk is that reference value.

2/It us the heat transfer due to convection and  conduction in Fluids. The conduction is in fluids very small compared to the influence of transport by the medium (convection).