- #1

Tymofei

- 8

- 2

Here i added a page from my fluid dynamics book where it shows particle model for deriving the equation. My question is why pressure is more at stream side aka 'positive "s" direction'.I would expected more pressure on the other side because for example when you trying to push a rigid object or some system like train vagon system,every differantial mass part/vagon parts should have same acceleration so inner force difference acting on differrantial mass part should be equilevant to dm * acceleration.And on the 'back' aka 'force applied side' of that particle there should be always more force applied on back compared to front side where difference is again dm * a = dF.Whats wrong with fluids does they perceive more pressure/force on their front side?So how they can accalerate then at positive 's' direction?Isnt that a contradiction ? I am confused..