Instructor: Lichuan Gui lichuan-gui@uiowa

1. Measurements in Fluid Mechanics058:180 (ME:5180)Time & Location: 2:30P - 3:20P MWF 3315 SCOffice Hours: 4:00P – 5:00P MWF 223B-5 HL Instructor: Lichuan Gui lichuan-gui@uiowa.edu Phone: 319-384-0594 (Lab), 319-400-5985 (Cell) http://lcgui.net

2. Lectures - around 40 lectures in class room followed by discussions if necessary - lecture note available on web after each class (http://icon.uiowa.edu & http://lcgui.net ) Homework - homework problems assigned MWF, due FMW - Paper version accepted in class, PDF/DOC files accepted by e-mail - late submission with legitimate reason, explained in writing Class project - write computer program with Matlab(sample programs provided) - process digital particle image (PIV) recordings with algorithms introduced in class - start at the beginning of PIVlectures (Matlab program practice & examples earlier) - details may be discussed in the class or office hours - presentation in class when the class lectures are completed - report include introduction, method description, program structure, source code, and results. Examinations - two in-semester 50-minute and one final 120-minute examinations - closed notes and books - one-page formula sheet allowed.

4. Measurement in Fluid Mechanics, Stavros Tavoularis, 2005, Cambridge, 2005 Particle Image Velocimetry, Raffelet. al., 2ndEdition, 2007, Springer Particle Image Velocimetry, Adrian and Westerweel, 2011, Cambridge Flow Visualization, Wolfgang Merzkirch, 2nd Edition, 1987, Academic

5. Lecture 1. Fluid properties and continuum hypothesis

6. Measurements in Fluid Mechanics Mechanics - the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment. Fluid - fluids are easily deformation materials and take the shape of any container - fluids include liquids and gases Liquids - relatively high density and difficult to change volume - relatively low density and easily to change volume Gases - tend to occupy the entire available volume of their container - fluids are composed of molecules that collide with one another and solid objects. Continuum hypothesis - the continuum assumption considers fluids to be continuous. - fluid property values continuously distributed within volume of fluid - local values defined at an infinitely small fluid element i.e. a mathematical point

7. Measurements in Fluid Mechanics Fluid mechanics - the study of fluids and the forces on them - fluid mechanics can be divided into fluid statics - the study of fluids at rest fluid kinematics - the study of fluids in motion; fluid dynamics - the study of the effect of forces on fluid motion experimental fluid dynamics (EFD) computational fluid dynamics (CFD) Measurement - the process or the result of determining the ratio of a physical quantity, such as a length or a mass, to a unit of measurement, such as the meter or the kilogram. Measurements in Fluid Mechanics - Methods and techniques used in the process or for result analysis of determining force, motion and other physical quantities of fluids

8. Measurements in Fluid Mechanics International System of Units (SI)

9. Measurements in Fluid Mechanics International System of Units (SI)

10. Measurements in Fluid Mechanics International System of Units (SI)

11. Measurable fluid properties Mass - quantity of material ( m ) SI unit: kilogram (kg), gram (g) Volume - quantity of space ( V ) SI unit: cubicmeter (m3), liter (=0.001 m3) Density - mass per unit volume (  ) SI unit: kg/m3 Specific volume - volume divided by mass (v) SI unit: m3/kg Force - any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape ( F ) SI unit: newton (N) Body force - acts throughout the volume - e.g. gravity and electromagnetic forces Surface force - acts across an internal or external surface element - decomposed in to two perpendicular components Normal component (Fn) F Tangential or shear component (Fs) - force per unit area () SI unit: pascal (Pa=1N/m2) A Fs n=Fn/A Shear stress s=Fs/A

12. Measurable fluid properties Stress tensor Normal stresses: 11 , 22 , 33 Shear stress: 12 , 13 , 21 , 23 , 31 , 32 (12 = 21 , 13 = 31 , 23 = 32) External forces: F1 , F2 ,, Fn Pressure - force per unit area applied in a direction perpendicular to the surface - average normal stress along any three orthogonal directions - Symbol: P SI unit: pascal (Pa=1N/m2), bar (=105Pa) Viscosity - resistance to deformation because of shear stress (µ, ) SI unit: Pas=kg/(sm) Surface tension - property of the surface of a liquid that allows it to resist an external force. SI unit: N/m Index of refraction - a measure of the speed of light in substance

13. Measurable fluid properties Temperature - quantitatively expresses the common notions of hot and cold ( T ) SI unit: kelvin (K) Energy - the ability a physical system has to do work on other physical systems ( E ) SI units: joule [J] Work - the amount of energy transferred by a force acting through a distance in the direction of the force. ( W ) SI units: joule [J] Heat - an energy transfer to the body in any other way than due to work performed on the body ( Q ) SI units: joule [J] Power SI units: watt [W] - the rate at which work is performed or energy is converted. ( P ) Thermal conductivity - material's ability to conduct heat () SI unit: W/(mK)

14. Measurable fluid properties - the rate of heat energy transfer through a given surface SI unit: W/m2 Heat flux Heat capacity - measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount. ( C ) SI unit: J/K Specific heat capacity under constant pressure ( CP ) SI unit: J/(kgK) Specific heat capacity under constant volume ( CV ) SI unit: J/(kgK) Internal energy - total energy contained by a thermodynamic system ( U ) SI unit: J Enthalpy (H) - total energy of a thermodynamic system H=U+pV Entropy ( S ) - thermodynamic property that can be used to determine energy available for useful work in thermodynamic process dS=Q/T

15. Measurable fluid properties Position - Cartesian coordinate system (x, y, z) P=xi+yj+zk - Cylindrical coordinate system (, , z) P=cosi+sinj+zk - Spherical coordinate system (r, , ) P=rsincosi+rsinrsinj+rcosk

16. Measurable fluid properties - shortest distance from the initial to the final position of a point (x, y, z) Displacement P=xi+yj+zk Velocity - the rate and direction of changein the position of an object z x y V=P/t=x/ti+y/tj+z/tk Acceleration - rate of change of velocity over time a=V/t=[V(t+t)-V(t)]/t

17. Measurable fluid properties Vn Volume flow rate Q A Mass flow rate Vorticity - tendency for elements of the fluid to "spin." - rate of change in strain with respect to time ( ) Strain rate - length under applied stress - original length v - speed of deformation

18. Measurable fluid properties Angular position (  ) SI unit: radian Angular displacement (  ) Angular velocity (  ) =d/dt =d/dt=d2/dt2 Angular acceleration (  ) Momentum - product of the mass and velocity of an object (P=mv). SI unit: kgm/s or Ns Angular momentum L=rP= rmv SI unit: Nmsor kgm2s−1 Torque (  ) =rF SI unit: Nm

19. Homework - Read textbook 1.1-1.2 on page 3-5 • Questions and Problems: 1 and 2 on page 17 • 1. Provide definitions for the following measureable flow properties: angular momentum, entropy, thermal conductivity, molecular diffusivity, and surface tension. • 2. List the established names for the SI units of force, pressure, energy, and power and their relationships to primary units. Also list the conversion factors of these units to corresponding units in the British gravitational system. - Due on Friday, 08/24 - Send MS Word or PDF file to lichuan-gui@uiowa.edu