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Resistance in Fluid Systems Mr. Andracke Principles of Technology.

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Presentation on theme: "Resistance in Fluid Systems Mr. Andracke Principles of Technology."— Presentation transcript:

1 Resistance in Fluid Systems Mr. Andracke Principles of Technology

2 Viscosity Viscosity has the units of (pressure) (time). The SI units for viscosity are Pa x s F drag = x Av/ y

3 Stokes Law Irishmen George Stokes used viscosity and the equations of fluid flow to predict the drag force on a sphere moving through a fluid. Stokes Law applies to objects moving at low enough speeds that the flow of fluid is streamlined or laminar.

4 Stokes Law F drag = 6 rv 6 =Constant for sphere R = Radius of object V = Speed of object = Fluids Viscosity

5 Stokes Law F drag = 6 rv Example:

6 Poiseuilles Law Poiseuille was a physician, who experimented with flowing water, and learned that the rate at which fluid flows through a tube increases proportionately to the pressure applied the fourth power of the radius of the tube. Poiseuilles Law gives the volume flow rate of a fluid flowing through a tube or pipe.

7 3 Factors of Resistance In fluid flow resistance decreases the flow rate though a pipe. Poiseuilles Law shows how this resistance depends on three factors: Dependence on Radius Dependence on Length Dependence on Viscosity

8 Dependence on Radius The larger the radius of a pipe, the greater volume of fluid per second Fluid resistance decreases as pipe radius and cross-sectional area increase.

9 Dependence on Length Longer pipes have higher fluid resistance Volume flow rate is inversely proportional to length

10 Dependence on Viscosity Abrupt changes in the direction of fluid flow can cause turbulence and increase resistance Fluid resistance increases as viscosity increases.

11 Poiseuilles Law V = - r 4 8 L R = Radius of Pipe or Tube = P 2 – P 1 = Viscosity L = Length of Pipe or Tube

12 Poiseuilles Law V = - r 4 8 L Example:

13 Poiseuilles Law Help with Poiseuille's Law astr.gsu.edu/hbase/ppois.html

14 Any Questions?? Complete the Math Lab Activity & Receive Handout for Tomorrows Lesson


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