We both know that the most important thing is to have some gentle airflow. The direction and volume are less important.

The secondary bay in the MythTV box here is like that.. the two drives lay horizontally above the slim fan. Not optimal for cooling, but good enough, and quieter perhaps than a side fan in this instance.

There's a 4TB Seagate in that bay by itself now, and it is idling at 33C (current ambient is around 22C). I'm quite happy with that!

Cheers