I recommend you to look at the Biot number of your problem. It is a dimesionless number given by : Bi = Lc*h/k (where Lc is a characteristic length of your problem and k the conductivity of your material)

It is very useful to operate great simplifications in thermal transfer problems such as yours. It basically computes the ratio of "how fast you transfer heat to the surface" to "how fast you transfer heat inside the material".

A small Biot number (Bi<<1, tipically Bi<0.1) implies that you have a "thermally thin" body, which means that the heat diffusion process inside will occur much faster than the one to the surface. In this case, you can consider your piece of metal to be homogeneous in temperature for your problem.

In case your Biot number is big (Bi~1), then you should take into account internal diffusion, and model the inside of your material.

Hope that helped !

I recommend you to look at the Biot number of your problem. It is a dimesionless number given by : Bi = Lc*h/k (where Lc is a characteristic length of your problem and k the conductivity of your material)

It is very useful to operate great simplifications in thermal transfer problems such as yours. It basically computes the ratio of "how fast you transfer heat to the surface" to "how fast you transfer heat inside the material".

A small Biot number (Bi<<1, tipically Bi<0.1) implies that you have a "thermally thin" body, which means that the heat diffusion process inside will occur much faster than the one to the surface. In this case, you can consider your piece of metal to be homogeneous in temperature for your problem.

In case your Biot number is big (Bi~1), then you should take into account internal diffusion, and model the inside of your material. The estimation of h can be done as proposed by pentane. This kind of measurement is anyway very common, and I think that a quick internet search on engineering websites will give you a whole variety of procedures you can pick from.

Hope that helped !