Dynamic Similarity

1 / 12

# Dynamic Similarity - PowerPoint PPT Presentation

Dynamic Similarity. http://www.typefreediabetes.com/Articles.asp?ID=150. http://www.eosnap.com/?tag=strait-of-gibraltar. inertial vs viscous. Reynolds Number. Flow is laminar when Re &lt; 1000. Flow is in transition to turbulence when 100 &lt; Re &lt; 10 5 to 10 6.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Dynamic Similarity' - eshana

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Dynamic Similarity

http://www.typefreediabetes.com/Articles.asp?ID=150

http://www.eosnap.com/?tag=strait-of-gibraltar

inertial vs viscous

Reynolds Number

Flow is laminar when Re < 1000

Flow is in transition to turbulence when 100 < Re < 105 to 106

Flow is turbulent when Re > 106, unless the fluid is stratified

Low Re

High Re

Consider an oceanic flow where U = 0.1 m/s; L = 10 km; kinematic viscosity = 10-6 m2/s

Is friction negligible in the ocean?

Froude Number

inertial vs pressure

http://www.yourlocalweb.co.uk/greater-manchester/city-of-manchester/higher-blackley/pictures/http://www.yourlocalweb.co.uk/greater-manchester/city-of-manchester/higher-blackley/pictures/

Euler Number

pressure vs inertial

Great Fountain Geyser, Yellowstone National Park, USA

http://www.freefoto.com/browse/1222-02-0?ffid=1222-02-0

Strouhal Number

local vs inertial

f = frequency of motion; A = amplitude of motion – for flying or swimming organisms (fin or wing)

Taylor at al. (2003, Nature425, 707-711(16 )

doi:10.1038/nature02000)

“Left panels, root-flapping motion; right panels, heaving motion. Amplitude, twice wing chord; static angle of attack, 15°; flow speed, 1.5 ms-1; smoke wire visualizations made at end of downstroke.

a, For St < 0.10, flow separates at the sharp leading-edge, but no discrete vortex forms.

b, For 0.10 < St < 0.25, a leading-edge vortex forms but is shed before the downstroke ends.

c, For 0.25 < St < 0.45, the leading-edge vortex is shed as the downstroke ends.

d, For St > 0.45, trailing edge separation produces a characteristic mushroom-shaped wake.

At higher St, the wing collides with shed vorticity on the upstroke, giving an energetically inefficient mode.”

http://www.nature.com/nature/journal/v425/n6959/fig_tab/nature02000_F1.html#figure-title

Dynamic Similarity

http://www.typefreediabetes.com/Articles.asp?ID=150

http://www.eosnap.com/?tag=strait-of-gibraltar