What is direction of energy flow for all Yin Channels
I would start by asking you, why you are asking about directional flow? I ask this because I feel like people over state the concept of “energy flow” through the “channels”. There are many views on this and a directional flow is not wrong per se, but the points are often better thought of (in my opinion) as wells that go into a web of fascia (read about the muscle/sinew channels in acupuncture in texts such as “Illustrations of the Complete Acupuncture System: The Sinew, Luo, Divergent, Eight Extraordinary, Primary Channels and all their Branches” to better understand these concepts). Viewed as a well the idea of a directional channel becomes less significant.
That said, I would start be reading about entry/exit points as well to start to understand one important way that the channels interact with each other.