[aerodinamika]

Hello all,

I have an issue in ANSYS 2019R3 Fluent when I try to model forced convection in a transient simulation. The case is as follows:

- I have a disk made out of steel which is in a sufficiently sized control volume meshed with poly-hexcore elements
- SST k-omega turbulence model
- skewness below 0.63
- Coupled pressure-velocity coupling
- Standard initialization
- Initial temperature of the disk is T_d = 573 K
- Ambient temperature is T_amb = 300 K
- Velocity inlet BC with u = 15 m/s
- Pressure outlet BC with 0 gauge pressure
- Ground has a moving wall BC at u = 15 m/s
- Heat transfer BCs will be shown separately in one of the following images
(disk-poly is the interface with the solid disk, while disk-shadow is the interface between the solid zone and the fluid zone, both have the same BC)
disk_air.png
disk_solid.png

I am trying to analyze heat transfer by oncoming airflow at the defined speed. I did some pretty basic hand calculations and got the following trend in MATLAB.
cfd_online.png

My first and biggest dilemma is why am I in post-processing seeing a trend of disk temperatures which is the complete opposite of what I am expecting? How can the temperature of the disk rise and keep its value at T_d = 573 K if there is constant air at temperatures of T_amb = 300 K going over it and forcing heat transfer via convection?
trend.png

I should mention that I tried modeling convection by adding a source term in the cell zone conditions, to no avail. Where am I going wrong with this approach?