Lecture 5 - Analytical, computational and experimental methods

Question 1

Analytical methods have?

Answer 1

A closed form solution. (solution can be expressed as an analytical function)

Question 2

What is the reductionist model?

Answer 2

Analysis aimed at simplifying a complex phenomenon into its component parts.

Question 3

What is the phenomenological model?

Answer 3

Analysis concerned only with observed phenomena, no emphasis on first principles.

Question 4

What is FSI?

Answer 4

Fluid Structure Interaction - interaction of some movable or deformable structure with an internal or surrounding flow.

Question 5

What do numerical methods for FSI suffer from?

Answer 5

1. Numerical Instability
2. Time step restriction
3. Parallel scalability issues
4. High computational costs

Question 6

Hierarchy of CFD models?

Answer 6

1. DNS
2. LES
3. hybrid RANS-LES
4. Unsteady RANS
5. RANS

Question 7

Wind tunnel experiment restrictions?

Answer 7

1. Flow at low Re is very sensitive to external influence
2. The wind tunnel may change flow around an aerofoil
3. The forces and pressures need to acquired with high precision
4. The wind tunnel must be built to high standards

Question 8

Experiment vs Simulation ?

Answer 8

Experiment - poor control, perfect model
Simulation - Excellent control, imperfect model

Question 9

Instrumentation for pressure measurements?

Answer 9

systems such as transducers that convert pressure into electric signals of appropriate frequency.

Question 10

Instrumentation for analysis flow direction?

Answer 10

tufts on surface of models, dyes and oils, smoke

Question 11

Instrumentation for turbulence levels?

Answer 11

LDA - Laser Doppler Anemometry
PIV - Particle Image Velocimetry

Question 12

Instrumentation for temperatures and temp gradients?

Answer 12

thermocouples or thermistors