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Density fingering of reaction-diffusion fronts in porous media

Density fingering of reaction-diffusion fronts in porous media. L. Macias; D. Müller; N. Berrueta; L. Riolfo and A. D'Onofrio. Grupo de Medios Porosos,Facultad de Ingeniería, Universidad de Buenos Aires, Argentina . In collaboration with:. A. De Wit P. Trevelyan.

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Density fingering of reaction-diffusion fronts in porous media

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  1. Density fingering of reaction-diffusion fronts in porous media L. Macias; D. Müller; N. Berrueta; L. Riolfo and A. D'Onofrio Grupo de Medios Porosos,Facultad de Ingeniería, Universidad de Buenos Aires,Argentina In collaboration with: A. De Wit P. Trevelyan Université Libre de Bruxelles A. Zalts C. El Hasi D. Rubio Universidad Nacional General Sarmiento

  2. Objectives Experimental study of Rayleigh-Taylor instability on reaction-diffusion fronts two kinds of reactions a simple exothermic neutralization reaction, NaOH solution and HCl solution (Acid-Base) the acid autocatalysis of Chlorite-Tetrathionate (CT). • Hele-Shaw cells and Porous Media

  3. What is the difference between the two kinds of reaction? Acid - Base CT reactants product V reactants concentration concentration product position position P. Trevelyan, A. De Wit. J. Yang, A. D´Onofrio, S. Kalliadasis, A. de Wit. J. Chem. Phys. 117, 9395 (2002) • Chemical kinetic constant q • The main difference is the stationary travelling wavefront qAB = 1.4×1011 M-1s-1 qCT = 2.4×104 M-3s-1

  4. Rayleigh – Taylor instability modified by chemical reaction in the interface without chemical reaction with chemical reaction g Grupo de Medios Porosos, FIUBA (2004) Grupo de Medios Porosos, FIUBA (2002)

  5. Rayleigh – Taylor instability modified by chemical reaction in the interface Rayleigh – Taylor instability modified by chemical reaction in the interface without chemical reaction with chemical reaction r product g reactants x Density profile Mixing zone is smaller D. Lima, A. D´Onofrio, A. De Wit, J. Chem. Phys. 124, 014509 (2006)

  6. Effect of temperature (CT reaction) Chlorite-Tetrathionate (CT) Is an exothermic reaction thermals effects are very important

  7. Effect of temperature (CT reaction) Temperature 1 cm 1 1 1 cm cm t = 80s t = 140s t = 140s t = 140s t = 140s t = 140s t = 210s t = 210s t = 210s t = 210s T = 12.4ºC T = 20.5ºC T = 39.4ºC G. Garcia Casado, L. Tofaletti, D. Müller, A. D´Onofrio,. J. Chem. Phys. 126, 114502 (2007)

  8. Effect of temperature (CT reaction) G. Garcia Casado, L. Tofaletti, D. Müller, A. D´Onofrio,. J. Chem. Phys. 126, 114502 (2007)

  9. Effect of temperature (CT reaction) G. Garcia Casado, L. Tofaletti, D. Müller, A. D´Onofrio,. J. Chem. Phys. 126, 114502 (2007)

  10. Front evolution at the inlet of the porous medium (CT reaction) Helle shaw cell Mixing zone t (s) Porous medium 3.5 cm Grupo de Medios Porosos, FIUBA (2006)

  11. Acid - Base reaction r r product Acid g Base reactants x x Density profile Acid - Base reaction Density profile CT reaction

  12. Acid - Base reaction Acid Base rA<rB 4.5 cm A. Zalts, A Ureña, D. Rubio, C. El Hasi, A. D´Onofrio. PRL (sent to publish)

  13. Acid - Base reaction Acid - Base reaction Equation of system Numerical results Base Acid g P. Trevelyan, A. De Wit.

  14. Acid - Base reaction 1 cm t=490min t=2520min t=6650min t=490min t=2518min t=6648 min t=260 min t=2518min t=6648min 0.03M 0.01M 0.1M

  15. Acid - Base reaction Acid - Base reaction Variations of the mixing zone as a function of time for different concentrations. Power spectra of the fingers for different concentrations. Note that the basic modes increases when the solution concentration increases.

  16. Conclusion Acid - Base reaction • The Rayleigh – Taylor instability is modified by chemical reactions in the interface producing a decrease of the mixing zone (CT reaction). • Temperature is a very important factor in this kind of systems as it could produce the disappearance of the instability (CT reaction). • Even with an initial stable density profile, this chemical reaction (Acid – Base reaction) develops instabilities. • In the Acid – Base case the mixing zone increases when the concentration decreases.

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