�?�?t ε l ρ l v l + �?�?ε l ρ l v l v l = ε l �?�?τ l + ε l ρ l g �?ε l �?p �?β v l �?v s The minimize in annular return circulation will lead to the circulation velocity of drilling https://vertechs.pixnet.net/blog/posts/872015993819260625