Slide 1

Transcript Slide 1

Engineering

• Engineer -> μηχανικος • Engineering ?-> μηχανικη ??

(College of Engineering -> ???) • Engineers create: -design and build machines, structures -analyze the function of engineering products • Engineering research

Engineering Mechanics

• Mechanics is a chapter of Physics • Engineering Mechanics employs mechanics to design and build • Engineering Mechanics: Solid Mechanics Fluid Mechanics Dynamics and Vibrations

Fluid Mechanics

• Bernoulli’s equation: 



1 2 2

  1 



2 2 2

g z

2 32 



2 (1) •Analytical methods •Computational methods •Experiments (facilities and instrumentation)

PIV Raw Data

(Particle Image Velocimetry)    Separation of phases based on size Cross correlation based PIV used to measure velocity of flow Particle tracking used to measure Particle and Bubble velocities

Flotation processes are part of multi-billion industrial activities (mining etc.)

Well-drained, with very thin lamellae and coagulation Well-drained foam with polyhedral bubbles Non-drained, nearly spherical bubbles at the interface

Foam column

Sneak Preview of Our Time-Resolved DPIV System

Image acquisition with enhanced time resolution: 1 10KHz Image Pre-Processing and Enhancement to Increase signal quality and perform image segmentation Novel Velocity Evaluation Methodology with accuracy better than 0.05 pixels and space resolution on the order of 4 pixels

Qualitative and Quantitative Flow Visualization

A coherent light source is used to illuminate the area of interest in the flow Very small particles serve as tracers of the motion of the fluid by scattering the light A Digital CCD Camera is used to collect the scattered light for a sequence of consecutive images Image processing of the acquired images results to a velocity distribution of the flow field

Image Pre-Processing

Image Calibration Remove background noise Dynamic Local Thresholds Sharpening Smoothing Edge Detection Erosion Determine the centroid with sub pixel accuracy Gaussian Center of Gravity Before After

Fluid Mechanics of the Heart

PIV measurements at 5 planes parallel to the axis of the ventricle 1 KHz sampling frequency 400 micron vector grid spacing 1 Hz heart rate Flexible/compliant walls fluid structure interaction Time resolved, unsteady measurements

Vortex Formation Downstream a SJM Bi-leaflet Mechanical Heart Valve

Aerodynamics

• Το Αεροδρομιο (aerodrome) Professor Langley was the director of the Smithsonian institute in the late 1800’s

Langley’s airplane (Sharp leading edges)

Airfoil Aerodynamics • Attached versus separated flow • Wake pressure is very low • But Bernoulli effect is stronger

The Wright Brothers Machine

Wings designed after careful experimentation

The Wright Brothers Wind Tunnel They tested wing sections to optimize their shape

VA Tech Stability Wind Tunnel

Facilities and models

– Stability Wind Tunnel with U ∞ =40 m/s Re≈10 6 – 44” span trapezoidal wing – Pressure taps – Seven-Hole Probes –

New: 3-D

Particle Image Velocimetry (PIV)

Flow animation for Treftz planes

Trefftz Planes,



=13 ° , Re=10

6 Axial velocity Vorticity

Trefftz Planes at Stability,



=21 °, Re=10