Fluid dynamic and CPB

force exerted per unit area
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Terms in this set (30)
Viscous forces generated within a fluid from intermolecular attraction between fluid moleculesViscosityHCT <10% =Newtonian fluidDecrease HCT = decreased? - how to maintain adequate pressureViscosity and resistance to flow - increase in flowEquation for resistanceR = n(L)/ r^4 n = viscosity R = resistance r = radius L = lengthFlow can be measure as?Velocity (cm/s) or volume (ml/s)Flow =change in pressure/resistanceno turbulence, layer of fluid nearest vessel wall moves more slowly than middle layer and maximum velocity of fluid at center of vesselLaminar flowStreamlines become mixed and dispersedTurbulent flowTurbulent flow dissipates energy in much largerQuantity and is uncontrolledTurbulent flow can result in1.) cavitation 2.) hemolysis 3.) inefficient flowSigns of turbulent flowBruit in vessel and murmur through heart valvesForce applied to an area of a liquid confined between two plates sufficient to set liquid in motionShear stressShear rateVelocity at which the liquid moves in proportion to the separation of the platesLower shear rates are associated with?Higher viscosity due to cellular elements tendency to aggregate or resist flowForce needed to induce flow of the non-Newtonian fluid (blood)Yield stressDetermination for laminar flow or turbulent flowReynolds's numberReynolds equation2(density)x(velocity)(r)/viscosity <2000 = laminar flow >3000 = turbulent flowGives the pressure drop in incompressible and Newtonian fluid in laminar flow through long cylindrical pipe of constant cross sectionPoiseullies lawPoiseullies law equationF=P(pi)r^4/ 8(n)(L)Why is poiseullies law not an accurate representation of flow dynamics in vessels?Blood in non-Newtonian Vessels are not long straight uniform radius There are area of turbulent flow