Bark side up, mostly.
If the bark was good enough to handle the weather when the tree was standing, it's good enough to handle any downward weather (rain) while it's laying down.
If the bark starts to separate from the wood while drying, it tends to make a great water reservoir, so bark down can catch water and pool it, keeping moisture in my pile. I want it to shed all the water away, so it can dry faster.
$0.02
If the bark was good enough to handle the weather when the tree was standing, it's good enough to handle any downward weather (rain) while it's laying down.
If the bark starts to separate from the wood while drying, it tends to make a great water reservoir, so bark down can catch water and pool it, keeping moisture in my pile. I want it to shed all the water away, so it can dry faster.
$0.02