## Fluids

#### Transient Laminar Heat transfer between hot air and cold aluminium

• Laurie Galanti
Subscriber
Hello, I am currently working on the modeling of the heat transfer of an oven and more precisely on the heat rise of the aluminum plate thanks to the hot air circulating in the oven. However, I encounter a problem during my simulations: when I model the heat exchange in stationary and laminar no problem the cold plate is heated progressively by the air (cf. picture 1) but in transient and laminar the plate remains cold I can not simulate the transfer of hot air to the plate (cf. picture 2) would you have an answer to this problem? Thanks  (initialization : plate at 27°C and inlet air at 500°C)

• Rob
Ansys Employee

How many time steps have you run?

• Laurie Galanti
Subscriber

For the transient, number of time steps : 300 and time steps size 10 second

• Rob
Ansys Employee

Odd as there should be no difference in heat transfer between steady and transient at the equilibrium state.  What's the heat flux over the wall between the solid and fluid? What are the boundary conditions around the domain?

• Laurie Galanti
Subscriber

Concerning the boundary conditions, all the "walls" of the plate are coupled and I also set the initialization of the solid ( patch : température 27°C for the plate)  so the heat flux at the plate's walls is 0 for the both simulation (steady and transient). Moreover, I also created a boolean during the geometry with the air of the oven as target body and the plate as tool body and I don't know if it can be linked to my problem.

• Laurie Galanti
Subscriber

I continued to look for the difference between transiant and steady and I realized that the method used was not the right one for solid time stepping, it must be switched to automatic (see picture). thanks for your help!

• Rob
Ansys Employee

Ah, so the solid was heating/cooling too quickly. Good spot.