I have a pipe with ID=75 mm interrupted with an array of N=121 tubes (as shown in the drawing), forcing the air to flow inside the tubes (ID of each tube is 2mm) spaced apart by 5mm. How do I estimate the pressure drop of the outcoming air? If there is a white paper on this, I would appreciate a reference! My application would benefit from maximizing the N of tubes and reducing their IDs, but I need to know when to stop (i.e. when the air pressure drop becomes impractical). I am aware of this thread which treats a different configuration (cross-flow around the tubes): https://engineering.stackexchange.com/questions/50140/method-for-computing-the-pressure-drop-across-a-bank-of-tubes [![enter image description here][1]][1] [1]: https://i.sstatic.net/L0qSa.png