[redwanamit034]

Hello,

I am doing a transient conjugate heat transfer analysis of a solid and fluid zone in two steps in Fluent. In the first step, the solid zone is heated with a volumetric heat source and high velocity fluid (Helium gas) is flowing around the solid. After a certain period of time, the Helium flow is stopped. In the second step, the cooling of the solid part for the remaining period of time is done by still air.

What I have done in my simulation is - I have created a solid zone and fluid zone of Helium. The conjugate heat transfer of this two zones looks okay. However, for my second step I have changed the material of the fluid zone from He to air. I have changed the inlet velocity to 0 m/s as the air is stagnant.
I am getting reversed flow in pressure outlet message. The solution in each time step doesn't also converge.

Can you suggest me few tips here?

I am thinking of exporting the result (temperature) of the solid zone at the end of first step. And then start a new Fluent case file where I will import the results of first step, introduce a new fluid zone and then run the simulation. Is it doable? If so, how?

How can I do that?

[sescobar]

For your second step try changing the boundary from velocity inlet for something more suitable, perhaps symmetry or periodic. It depends on your configuration.
In order to initialize a simulation using the temperature or velocity field from a previous simulation: first open the data case corresponding to your solution and write the interpolation file for the desired cell zone (file/interp/write-data). Second, read the new case file and read interpolation file (file/interp/read-data).
Cheers