Experimental Methods in Thermal Sciences






Brief Syllabus:

Introduction, Details of an experimental setup, Static versus dynamic calibration, Design of experiments. Uncertainty analysis, Central limit theorem, Normal and Student’s-t distribution, Data outlier detection, Error propagation. Temporal response of probes and transducers, Measurement system model, zeroth, first, and second order systems, Probes and transducers, pressure transducers, pitot static tube, 5-hole probe, Hotwire anemometer, Laser Doppler velocimetry, Particle image velocimetry, Thermocouples, RTD, Thermister, Infrared thermography, Heat flux measurement, Interferometry, Schlieren and shadowgraph techniques, Holography, Measurements based on light scattering, Absorption spectroscopy, Mie scattering, Rayleigh, Raman and other scattering methods, Data acquisition systems, Analog to digital converter, Resolution, Quantization error, Signal connections, Signal conditioning, Digital signal and image processing, Review of numerical techniques, interpolation; curve fitting (regression), integration, differentiation, root finding, Solving a system of linear algebraic equations, Treatment of periodic data, Fourier analysis, FFT algorithm, Inverse FFT, Nyquist criterion, Numerical aspects of FFT, probability density function, auto- and cross-correlations, Optical tomography, ART family of algorithms Inverse techniques.

Lecture-wise breakup

 I: Introduction: Experiments versus simulation, Experiments versus measurements, Why conduct experiments, Details of an experimental setup, Principles of similarity; Global versus local measurements; Static versus dynamic calibration. (2 lectures)

 II: Design of experimen: issues related to probe selection, factorial design, design of experiments based on sensitivity function and uncertainty analysis. Examples related to (a) determining the duration of the experiment and (b) choosing between steady state and transient techniques. Forward versus inverse measurements, Examples related to wake survey, drag coefficient, and heat transfer coefficient. (2 lectures)

 III: Uncertainty analysis Nomenclature: precision versus accuracy, measurement errors, sampling, A/D conversion, attenuation, phase lag, signal-to-noise ratio, calibration. scatter, central limit theorem, 95% confidence interval, normal and Student’s-t distribution, data outlier detection, uncertainty, combining elemental errors, error propagation. (4 lectures)

 IV: Temporal response of probes and transducers: measurement system model, system response, amplitude response, frequency response, zeroth, first, and second order systems; examples of thermocouple response and U-tube manometer. Probe compensation in the frequency domain. (4 lectures)

 V: Probes and transducers: Pressure - pressure transducers; noise measurement
Velocity - pitot static tube (low as well as high speeds), 5-hole probe, Hotwire anemometer, CCA, CTA, Laser Doppler velocimetry, Particle image velocimetry.  Temperature measurement: thermocouples, RTD, thermister, infrared thermography, Heat flux measurement,  (10 lectures)

 VI: Refractive index based optical measurement techniques:Introduction to lasers, interference, interferometry, fringe analysis; Schlieren and shadowgraph techniques; Image analysis using ray tracing technique; Holography (5 lectures)

 VII: Measurements based on light scattering:absorption spectroscopy, shadow formation, Mie scattering, Rayleigh, Raman and other scattering methods. (3 lectures)

 VIII: Data acquisition systems:analog input-output communication, analog to digital converter, static and dynamic characteristic of signals, Bits, Transmitting digital numbers, resolution, quantization error, signal connections, single and differential connections, signal conditioning. (3 lectures)

 IX: Digital signal and image processing:Digital signal processing compared with digital image processing signal conditioning. (6 lectures)

  • Review of numerical techniques: interpolation; curve fitting (regression), integration, differentiation, root finding, solving a system of linear algebraic equations. 

  • Treatment of periodic data; Fourier analysis, FFT algorithm; Inverse FT; Nyquist criterion. Numerical aspects of FFT; probability density function; auto- and crosscorrelations

  • Optical tomography, ART family of algorithms 
    Inverse techniques: Determination of thermophysical properties using inverse techniques.

Demonstration experiments:

Several demonstration experiments will be used for explaining the implementation details of several experimental techniques. Some examples are:

  • Determination of wall shear stress of flat plate boundary layer; 

  • Determination of drag coefficient of circular cylinder in cross-flow;

  • time-averaged and rms fluctuations in a turbulent mixing layer; (d) viscosity measurement;

  • Determination of average Nusselt number of a circular cylinder in cross flow

  • Visualization using Interferometry, schlieren, shadowgraph, digital holography and infrared thermography

  • Velocity distribution around cylinder using PIV


  1. C. Tropea, A.L. Yarin, and J.F. Foss, Editors, Springer Handbook of Experimental Fluid Mechanics, 2007.

  2. T.G. Beckwith and N.L. Buck, Mechanical Measurements, Addison-Wesley, MA (USA), 1969.

  3. H.W. Coleman and W.G. Steele Jr., Experiments and Uncertainty Analysis for Engineers, Wiley & Sons, New York, 1989.

  4. E.O. Doeblin,  Measurement Systems, McGraw-Hill, New York, 1986.

  5. R.J. Goldstein (Editor), Fluid Mechanics Measurements, Hemisphere Publishing Corporation, New York, 1983; second edition, 1996.

  6. J. Hecht, The Laser Guidebook,  McGraw-Hill, New York, 1986.

  7. B.E. Jones, Instrumentation Measurement and Feedback, Tata McGraw-Hill, New Delhi, 2000.

  8. M. Lehner and D. Mewes,  Applied Optical Measurements, Springer-Verlag, Berlin, (1999).

  9. F. Mayinger, Editor, Optical Measurements: Techniques and Applications, SpringerVerlag, Berlin, 1994. 

  10. D.C. Montgomery, Design and Analysis of Experiments, John Wiley, New York, 2001.

  11. A.S. Morris, Principles of Measurement and Instrumentation, Prentice Hall of India, New Delhi, 1999.

  12. F. Natterer, The Mathematics of Computerized Tomography, John Wiley & Sons, New York, 1986.

  13. P.K. Rastogi, Ed., Photomechanics, Springer, Berlin, 2000.

  14. M. Van Dyke, An Album of Fluid Motion, The Parabolic Press, California, 1982.