development of fdo patterns in the bz reaction l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Development of FDO Patterns in the BZ Reaction PowerPoint Presentation
Download Presentation
Development of FDO Patterns in the BZ Reaction

Loading in 2 Seconds...

play fullscreen
1 / 29

Development of FDO Patterns in the BZ Reaction - PowerPoint PPT Presentation


  • 137 Views
  • Uploaded on

Development of FDO Patterns in the BZ Reaction. Steve Scott University of Leeds. Acknowledgements. Jonnie Bamforth (Leeds) Rita T ó th (Debrecen) Vilmos G áspár (Debrecen) British Council/Hungarian Academy of Science ESF REACTOR programme.

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

PowerPoint Slideshow about 'Development of FDO Patterns in the BZ Reaction' - shiela


An Image/Link below is provided (as is) to download presentation

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
acknowledgements
Acknowledgements
  • Jonnie Bamforth (Leeds)
  • Rita Tóth (Debrecen)
  • Vilmos Gáspár (Debrecen)
  • British Council/Hungarian Academy of Science
  • ESF REACTOR programme
flow distributed oscillations

Kuznetsov, Andresen, Mosekilde, Dewel, Borckmans

Flow Distributed Oscillations
  • patterns without differential diffusion or flow
  • Very simple reactor configuration: plug-flow tubular reactor fed from CSTR
  • reaction run under conditions so it is oscillatory in batch, but steady-state in CSTR
simple explanation
Simple explanation
  • CSTR ensures each “droplet” leaves with same “phase”
  • Oscillations occur in each droplet at same time after leaving CSTR and, hence, at same place in PFR
slide5
Explains:

existence of stationary patterns

need for “oscillatory batch” reaction

BZ system with f = 0.17 cm s-1

[BrO3-] = 0.24 M, H+ = 0.15M[MA] = 0.4 M, [Ferroin] = 7 ´ 10-4 M

Images taken at 2 min intervals

slide8
Doesn’t explain

critical flow velocity

nonlinear dependence of wavelength on flow velocity

other responses observed, especially the dynamics of pattern development

analysis
Analysis
  • Oregonator model:

Has a uniform steady state uss, vss

slide10
Perturbation: u = U + uss, v = V + vss

linearised equations

Seek solutions of the form

dispersion relation
Dispersion relation

Tr = j11 + j22

D = j11j22 – j12j21

absolute to convective instability
Absolute to Convective Instability

Look for zero group velocity, i.e. find k = k0such that

gives

so

Setting Im(w(k0)) = 0 gives fAC

bifurcation to stationary patterns
Bifurcation to Stationary Patterns

Required condition is w = 0 with Im(k) = 0

Setting w = 0 yields

So Im(k) = 0 gives critical flow velocity

initial development of stationary pattern
Initial Development of Stationary Pattern
  • Oregonator modele = 0.25f = 1.0q = 8  10-4f = 2 0.4 time units per frame
experimental verification
Experimental verification

BZ system with f = 0.17 cm s-1[BrO3-] = 0.2 M, H+ = 0.15M[MA] = 0.4 M, [Ferroin] = 7 ´ 10-4 M

adjustment of wavelength to change in flow velocity
Oregonator model as before,

Pattern already established

now change f from 2.0 to 4.0

Adjustment of wavelength to change in flow velocity
nonlinear l f response
Nonlinear l-f response

e = 0.8

e = 0.5

e = 0.25

complex pattern development
Complex Pattern Development

e = 0.25f = 1.0q = 8  10-4f = 1.5 0.4 time units per frame

cdima reaction
CDIMA reaction

Patterns

but unsteady

lengyel epstein model
Lengyel-Epstein model
  • a= 0.5f = 5 0.12 time units per frame