# Heat Exchange

In interface TYPE7 there are three heat exchanges: heat transfer, radiation and heat friction are allowed by Ithe=1.

For heat transfer between secondary and main with Iform_the, two different heat transfer can be defined. One is set constant temperature in interface where, heat exchange is only between this interface and shell secondary side. The other is heat exchange between all pieces in contact.

If Frad≠ 0, then radiation is computed inside of distance Drad (max. distance for radiation computation). It is recommended to not set too high of a value for Drad , otherwise Radioss Engine performance may be reduced.

Using Fheats and Fheatm frictional sliding energy will be converted into heat. Since friction heat is divided between secondary and main side, generally Fheats + Fheatm < 1.0. The frictional heat QFric is defined:

If Iform=2 (a stiffness formulation):

Secondary side:

${Q}_{Fric}=Fhea{t}_{s}\cdot \frac{\left({F}_{adh}-{F}_{t}\right)}{K}\cdot {F}_{t}$

Main side:

${Q}_{Fric}=Fhea{t}_{m}\cdot \frac{\left({F}_{adh}-{F}_{t}\right)}{K}\cdot {F}_{t}$
(Ithe_form=1)

Here, $K$ is contact stiffness ${F}_{adh}$ is adhesive force.

If Iform=1 (a penalty formulation):

Secondary side:

${Q}_{Fric}=Fhea{t}_{s}\cdot C\cdot {V}_{t}{}^{2}\cdot dt$

Main side:

${Q}_{Fric}=Fhea{t}_{m}\cdot C\cdot {V}_{t}{}^{2}\cdot dt$