▁of ▁relax ation ▁( which ▁purely ▁depends ▁on ▁the ▁material ▁and ▁other ▁conditions ▁like ▁the ▁temperature ) ▁to ▁the ▁characteristic ▁time ▁of ▁experiment ▁or ▁observation . ▁Small ▁Deb or ah ▁numbers ▁represent ▁Newton ian ▁flow , ▁while ▁▁ ▁non - New ton ian ▁( with ▁both ▁vis c ous ▁and ▁el astic ▁effects ▁present ) ▁behaviour ▁occurs ▁for ▁intermediate ▁range ▁Deb or ah ▁numbers , ▁and ▁high ▁Deb or ah ▁numbers ▁indicate ▁an ▁el astic / rig id ▁solid . ▁Since ▁Deb or ah ▁number ▁is ▁a ▁relative ▁quantity , ▁the ▁numer ator ▁or ▁the ▁denomin ator ▁can ▁alter ▁the ▁number . ▁A ▁very ▁small ▁Deb or ah ▁number ▁can ▁be ▁obtained ▁for ▁a ▁fluid ▁with ▁extremely ▁small ▁relax ation ▁time ▁or ▁a ▁very ▁large ▁experimental ▁time , ▁for ▁example . ▁ ▁Reyn olds ▁number ▁▁ ▁In ▁fluid ▁mechan ics , ▁the ▁Reyn olds ▁number ▁is ▁a ▁measure ▁of ▁the ▁ratio ▁of ▁in ert ial ▁forces ▁() ▁to ▁vis c ous ▁forces ▁() ▁and ▁consequ ently ▁it ▁quant ifies ▁the ▁relative ▁importance ▁of ▁these ▁two ▁types ▁of ▁effect ▁for ▁given ▁flow ▁conditions . ▁ ▁Under ▁low ▁Reyn olds ▁numbers ▁vis c ous ▁effects ▁domin ate ▁and ▁the ▁flow ▁is ▁l amin ar , ▁whereas ▁at ▁high ▁Reyn olds ▁numbers ▁in ert ia ▁pre domin ates ▁and ▁the ▁flow ▁may ▁be ▁tur bul ent . ▁However , ▁since ▁r he ology ▁is ▁concerned ▁with ▁flu ids ▁which ▁do ▁not ▁have ▁a ▁fixed ▁vis cos ity , ▁but ▁one ▁which ▁can ▁vary ▁with ▁flow ▁and