close

Вход

Забыли?

вход по аккаунту

?

How to Stir Turbulence? - HECekli

код для вставки
How to Stir Turbulence?
Hakki Ergun Cekli and Willem van de Water
Applied Physics Department
Eindhoven University of Technology
Manchester 2008
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Periodically Driven Turbulence
Mean Field Theory and Shell Models
Examples
A.v.d.Heydt, S.Grossman and D.Lohse, Phy.Rev.E (2003)
Combustion Engines
Geophysical Flows
Pulsative blood flow
DNS
A.K.Kuczaj, B.J.Geurts ,D.Lohse and W.v.d.Water, Europhy.Let.E (2006)
Response Maximum
at fв€— = f П„
П„ : Large Eddy Turn Over
Time
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Our Experiments
10 Horizontal & 7 vertical axes
О±i (t) = ПЂfi t + П†i
Prescribed phases φi and signs fi = ∓f
determine pattern
Precise position control
Angles О±i (t) sampled with 400 Hz, can be
correlated with turbulence
Other Experiments: Counter-rotating Disks
O.Cadot, J.H.Titon and D.Bonn, J. Fluid Mech. (2003)
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Our Experiments
10 Horizontal & 7 vertical axes
О±i (t) = ПЂfi t + П†i
Prescribed phases φi and signs fi = ∓f
determine pattern
Precise position control
Angles О±i (t) sampled with 400 Hz, can be
correlated with turbulence
Other Experiments: Counter-rotating Disks
O.Cadot, J.H.Titon and D.Bonn, J. Fluid Mech. (2003)
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Grid Modes
Snapshots of a Cycle
Mode A
Mode B
Hakki Ergun Cekli and Willem van de Water
Mode C
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Quantifying Response
1
Time-Averaged Quantity
3
Phase-Averaged Quantity
Hakki Ergun Cekli and Willem van de Water
2
Frequency-Resolved Response
How to Stir Turbulence?
Response in Time-Averaged Quantity - Mode A
U = 9m/s
U = 6m/s
П„= L
U
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
U = 4m/s
Response in Time-Averaged Quantity - Mode A-B-C
U = 9m/s
Mode B
Mode A
Mode C
(Half-reversed motion) (Full-reversed motion)
Same Solidity
Different Rotation Direction
Different Response
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Refined Response (as in numerical simulations)
Spectrum
Response
Rf =
Mode A
Mode B
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Ef
E0
Mode C
Refined Response (Phase-Averaged Quantity)
Mode A
Mode B
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Mode C
Spatial Dependence - Energy Dissipation Rate
Mode A
Hakki Ergun Cekli and Willem van de Water
Mode B
How to Stir Turbulence?
Spatial Dependence - Response
Mode A
Hakki Ergun Cekli and Willem van de Water
Mode B
How to Stir Turbulence?
Conclusion
There are preferred frequencies
Details of the stirrer matter
How to characterize the stirrer?
Spatial structures affect the response in the tunnel
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
How to Stir Turbulence
Hakki Ergun Cekli and Willem van de Water
How to Stir Turbulence?
Документ
Категория
Без категории
Просмотров
7
Размер файла
3 492 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа