▁the ▁Western ▁World ▁that ▁claimed ▁that ▁blood ▁is ▁p ump ed ▁from ▁the ▁heart ▁and ▁rec ir cul ated . ▁Jean ▁Louis ▁Marie ▁Po ise u ille ▁is ▁cred ited ▁with ▁developing ▁the ▁theory ▁of ▁Po ise u ille ' s ▁Flow . ▁It ▁ ▁describes ▁the ▁relationship ▁between ▁flow ▁and ▁pressure ▁gradient ▁in ▁long ▁tub es ▁with ▁constant ▁cross ▁section . ▁Otto ▁Frank ▁published ▁the ▁" F und amental ▁form ▁of ▁the ▁ar ter ial ▁pul se ," ▁which ▁contained ▁his ▁" W ind k essel ▁theory " ▁of ▁circul ation ▁in ▁ 1 8 9 0 . ▁He ▁also ▁perfect ed ▁optical ▁man om eters ▁and ▁caps ules ▁for ▁the ▁precise ▁measurement ▁of ▁int ra - card iac ▁press ures ▁and ▁volumes . ▁ ▁Basic ▁Princi ples ▁of ▁Fl uid ▁Dynam ics ▁▁ ▁A ▁fluid ▁is ▁defined ▁as ▁a ▁subst ance ▁that ▁de forms ▁continu ously ▁under ▁application ▁of ▁a ▁she aring ▁stress , ▁regardless ▁of ▁how ▁small ▁the ▁stress ▁is . ▁Blood ▁is ▁a ▁primary ▁example ▁of ▁a ▁bi ological ▁fluid . ▁Air ▁can ▁also ▁be ▁considered ▁as ▁bi ological ▁fluid ▁as ▁it ▁flows ▁in ▁l ungs ▁and ▁the ▁syn ov ial ▁fluid ▁between ▁the ▁kne e ▁joint s ▁is ▁also ▁an ▁example ▁of ▁a ▁bi ological ▁fluid . ▁Types ▁of ▁Fl u ids ▁Fl u ids ▁can ▁be ▁class ified ▁into ▁four ▁basic ▁types . ▁They ▁are : ▁▁ ▁Ide al ▁Fl uid ▁ ▁Real ▁Fl uid ▁ ▁Newton ian ▁Fl uid ▁ ▁Non - New ton ian ▁fluid