Hi Robert Woolhouse,

Thank you for your comment but can you please clarify: How exactly do you make sure the solid is moving? Do you set Solid motion for the solid cell zone or it should be done in a different way?

I have a similar problem as user xatz. I am modeling an air oven that heats moving steel tubes in a steel tube factory. I modeled the geometry to include the airflow region of the oven with air inlet and outlet and modeled the steel tube as a hollow region at first and set motion to the walls using dynamic mesh. I used a UDF for the tube walls motion and set deformation for the air part. I also made sure that the tube is always in contact with the air part throughout its movement. The model worked well. 

But like User XATZ, I was not able to do any heat transfer analyses. So I am following your advice and including the steel tube as a solid body. I will use the same udf to make its walls move but how exactly I make the solid part move?