▁correction ▁step ▁is ▁to ▁ensure ▁conservation ▁of ▁mass . ▁In ▁continuous ▁form ▁for ▁compress ible ▁subst ances ▁mass , ▁conservation ▁of ▁mass ▁is ▁expressed ▁by ▁▁▁▁ ▁where ▁ ▁is ▁the ▁square ▁of ▁the ▁" speed ▁of ▁sound ". ▁For ▁low ▁Mach ▁numbers ▁and ▁in com press ible ▁media ▁ ▁is ▁assumed ▁to ▁be ▁infinite , ▁which ▁is ▁the ▁reason ▁for ▁the ▁above ▁continu ity ▁equation ▁to ▁reduce ▁to ▁▁▁▁ ▁The ▁way ▁of ▁obtain ing ▁a ▁velocity ▁field ▁satisfying ▁the ▁above , ▁is ▁to ▁compute ▁a ▁pressure ▁which ▁when ▁subst it uted ▁into ▁the ▁momentum ▁equation ▁leads ▁to ▁the ▁desired ▁correction ▁of ▁a ▁pre lim inary ▁computed ▁intermediate ▁velocity . ▁ ▁App lying ▁the ▁diver gence ▁operator ▁to ▁the ▁compress ible ▁momentum ▁equation ▁yields ▁▁▁▁▁ ▁then ▁provides ▁the ▁gover ning ▁equation ▁for ▁pressure ▁computation . ▁ ▁The ▁idea ▁of ▁pressure - cor re ction ▁also ▁exists ▁in ▁the ▁case ▁of ▁variable ▁density ▁and ▁high ▁Mach ▁numbers , ▁although ▁in ▁this ▁case ▁there ▁is ▁a ▁real ▁physical ▁meaning ▁behind ▁the ▁coupling ▁of ▁dynamic ▁pressure ▁and ▁velocity ▁as ▁ar ising ▁from ▁the ▁continu ity ▁equation ▁▁▁▁▁ ▁is ▁with ▁compress ibility , ▁still ▁an ▁additional ▁variable ▁that ▁can ▁be ▁elimin ated ▁with ▁algebraic ▁operations , ▁but ▁its ▁vari ability ▁is ▁not ▁a ▁pure ▁art ifice ▁as ▁in ▁the ▁compress ible ▁case , ▁and ▁the ▁methods ▁for ▁its ▁computation ▁differ ▁significantly ▁from ▁those ▁with ▁ ▁References ▁▁▁ ▁M . ▁Thom ad ak is , ▁M . ▁L esch z iner : ▁A ▁P RESS URE - C OR