ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-12-2205-2012 Numerical simulations of mixing conditions and aerosol dynamics in the CERN CLOUD chamber Voigtländer J. 1 Duplissy J. 2 3 Rondo L. 4 Kürten A. 4 Stratmann F. 1 Leibniz Institute for Tropospheric Research, Leipzig, Germany CERN, PH Department, Geneva, Switzerland Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland Institute for Atmospheric and Environmental Science, Goethe-University, Frankfurt/Main, Germany 29 02 2012 12 4 2205 2214 Copyright: © 2012 J. Voigtländer et al. 2012 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/12/2205/2012/acp-12-2205-2012.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/12/2205/2012/acp-12-2205-2012.pdf

To study the effect of galactic cosmic rays on aerosols and clouds, the Cosmics Leaving OUtdoor Droplets (CLOUD) project was established. Experiments are carried out at a 26.1 m<sup>3</sup> tank at CERN (Switzerland). In the experiments, the effect of ionizing radiation on H<sub>2</sub>SO<sub>4</sub> particle formation and growth is investigated. To evaluate the experimental configuration, the experiment was simulated using a coupled multidimensional computational fluid dynamics (CFD) – particle model. In the model the coupled fields of gas/vapor species, temperature, flow velocity and particle properties were computed to investigate mixing state and mixing times of the CLOUD tank's contents. Simulation results show that a 1-fan configuration, as used in first experiments, may not be sufficient to ensure a homogeneously mixed chamber. To mix the tank properly, two fans and sufficiently high fan speeds are necessary. The 1/e response times for instantaneous changes of wall temperature and saturation ratio were found to be in the order of few minutes. Particle nucleation and growth was also simulated and particle number size distribution properties of the freshly nucleated particles (particle number, mean size, standard deviation of the assumed log-normal distribution) were found to be distributed over the tank's volume similar to the gas species.

 European Commission CLOUD-ITN - CLOUD Initial Training Network (215072) ATMNUCLE - Atmospheric nucleation: from molecular to global scale (227463) References Berndt, T., O.&nbsp;B{ö}ge, and F.&nbsp;Stratmann: Formation of atmospheric H<sub>2</sub>SO<sub>4</sub>/H<sub>2</sub>O particles in the absence of organics: A laboratory study, Geophys. Res. Lett., 33, L15817, https://doi.org/10.1029/2006GL026660 , 2006. Berresheim, H. and T.&nbsp;Elste and C.&nbsp;Plass-D{ü}lmer and F.&nbsp;L.&nbsp;Eisele and D.&nbsp;J.&nbsp;Tanner: Chemical ionization mass spectrometer for long-term measurements of atmospheric OH and H<sub>2</sub>SO<sub>4</sub>, Int. J. Mass Spectrom., 202, 91–109, 2000. Brus, D., Hyv{ä}rinen, A.-P., Viisanen, Y., Kulmala, M., and Lihavainen, H.: Homogeneous nucleation of sulfuric acid and water mixture: experimental setup and first results, Atmos. Chem. Phys., 10, 2631–2641, <a href="http://dx.doi.org/10.5194/acp-10-2631-2010">https://doi.org/10.5194/acp-10-2631-2010</a>, 2010. Carslaw, K., R.&nbsp;Harrison, and J.&nbsp;Kirkby: Cosmic rays, clouds, and climate, Science, 298, 1732–1737, 2002. %Duplissy, J., et-al., Results from the cern pilot cloud experiment, Atm. Chem. % Phys., 10, 1635–1647, 2010. Duplissy, J., Enghoff, M. B., Aplin, K. L., Arnold, F., Aufmhoff, H., Avngaard, M., Baltensperger, U., Bondo, T., Bingham, R., Carslaw, K., Curtius, J., David, A., Fastrup, B., Gagnè, S., Hahn, F., Harrison, R. G., Kellett, B., Kirkby, J., Kulmala, M., Laakso, L., Laaksonen, A., Lillestol, E., Lockwood, M., M{ä}kel{ä}, J., Makhmutov, V., Marsh, N. D., Nieminen, T., Onnela, A., Pedersen, E., Pedersen, J. O. P., Polny, J., Reichl, U., Seinfeld, J. H., Sipilä, M., Stozhkov, Y., Stratmann, F., Svensmark, H., Svensmark, J., Veenhof, R., Verheggen, B., Viisanen, Y., Wagner, P. E., Wehrle, G., Weingartner, E., Wex, H., Wilhelmsson, M., and Winkler, P. M.: Results from the CERN pilot CLOUD experiment, Atmos. Chem. Phys., 10, 1635–1647, <a href="http://dx.doi.org/10.5194/acp-10-1635-2010">https://doi.org/10.5194/acp-10-1635-2010</a>, 2010. Eisele, F.&nbsp;L. and D.&nbsp;J.&nbsp;Tanner: Measurement of the Gas-Phase Concentration of H<sub>2</sub>SO<sub>4</sub> and Methane Sulfonic-Acid and Estimates of H<sub>2</sub>SO<sub>4</sub> Production and Loss in the Atmosphere, J. Geophys. Res., 98, 9001–9010, 1993. Enghoff, M. B. and Svensmark, H.: The role of atmospheric ions in aerosol nucleation – a review, Atmos. Chem. Phys., 8, 4911–4923, <a href="http://dx.doi.org/10.5194/acp-8-4911-2008">https://doi.org/10.5194/acp-8-4911-2008</a>, 2008. Hanson, D., and&nbsp;Eisele, F.: Diffusion of H<sub>2</sub>SO<sub>4</sub> in humidified nitrogen: Hydrated H<sub>2</sub>SO<sub>4</sub>, J. Phys. Chem. A, 104, 1715–1719, 2000. Fuller, E.&nbsp;N.,&nbsp;Schettler, P.&nbsp;D.. and&nbsp;Giddings, J.&nbsp;C.: A new method for prediction of binary gas-phase diffusion coefficients, Ind. Eng. Chem., 58, 18–27, 1966. Herrmann, E.,&nbsp;Brus, D.,&nbsp;Hyv{ä}rinen, A.-P.,&nbsp;Stratmann, F.,&nbsp;Wilck, M., &nbsp;Lihavainen, H., and &nbsp;Kulmala, M.: A computational fluid dynamics approach to nucleation in the water-sulfuric acid-system, J. Phys. Chem., 114, 8033–8042, 2010. IPCC2007: Climate change 2007, Tech. rep., Cambridge University Press, 2007. Jones, W. and&nbsp;Launder, B.: The prediction of laminarization with a two-equation model of turbulence, Int. J. Heat Mass Transfer, 15, 301–314, 1972. Kirkby, J.: Cosmic rays and climate, Surv. Geophys., 28, 333–375, 2007. % Kirkby, J., et~al., Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric %aerosol nucleation., % Nature, 476, 429–433, http://dx.doi.org/10.1038/nature10343https://doi.org/10.1038/nature10343, 2011. Kirkby, J.,&nbsp;Curtius, J.,&nbsp;Almeida, J.,&nbsp;Dunne, E.,&nbsp;Duplissy, J.,&nbsp;Ehrhart, S., &nbsp;Franchin, A.,&nbsp;Gagne, S., &nbsp;Ickes, L.,&nbsp;K{ü}rten, A.,&nbsp;Kupc, A.,&nbsp;Metzger, A., Riccobono, F.,&nbsp;Rondo, L.,&nbsp;Schobesberger, S.,&nbsp;Tsagkogeorgas, G., &nbsp;Wimmer, D., &nbsp;Amorim, A.,&nbsp;Bianchi, F.,&nbsp;Breitenlechner, M.,&nbsp;David, A.,&nbsp;Dommen, J., &nbsp;Downard, A.,&nbsp;Ehn, M., &nbsp;Flagan, R.&nbsp;C.,&nbsp;Haider, S., &nbsp;Hansel, A.,&nbsp;Hauser, D., &nbsp;Jud, W.,&nbsp;Junninen, H.,&nbsp;Kreissl, F.,&nbsp;Kvashin, A., &nbsp;Laaksonen, A.,&nbsp;Lehtipalo, K.,&nbsp;Lima, J.,&nbsp;Lovejoy, E.&nbsp;R.,&nbsp;Makhmutov, V.,&nbsp;Mathot, S.,&nbsp;Mikkila, J., &nbsp;Minginette, P.,&nbsp;Mogo, S.,&nbsp;Nieminen, T.,&nbsp;Onnela, A.,&nbsp;Pereira, P.,&nbsp;Petaja, T., &nbsp;Schnitzhofer, R., &nbsp;Seinfeld, J.&nbsp;H.,&nbsp;Sipila, M.,&nbsp;Stozhkov, Y.,&nbsp;Stratmann, F.,&nbsp;Tome, A.,&nbsp;Vanhanen, J.,&nbsp;Viisanen, Y., &nbsp;Vrtala, A.,&nbsp;Wagner, P.&nbsp;E.,&nbsp;Walther, H.,&nbsp;Weingartner, E.,&nbsp;Wex, H.,&nbsp;Winkler, P.&nbsp;M.,&nbsp;Carslaw, K.&nbsp;S., &nbsp;Worsnop, D.&nbsp;R.,&nbsp;Baltensperger, U., and&nbsp;Kulmala, M.: Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation., Nature, 476, 429–433, <a href="http://dx.doi.org/10.1038/nature10343">https://doi.org/10.1038/nature10343</a>, 2011. Kuang, C.,&nbsp;McMurry, P.,&nbsp;McCormick, A., and&nbsp;Eisele, F.: Dependence of nucleation rated on sulfuric acid vapor concentration in diverse atmospheric locations, J. Geophys. Res., 113, D10209, https://doi.org/10.1029/2007JD009253, 2008. Kulmala, M.,&nbsp;Vehkamki, H.,&nbsp;Petj, T.,&nbsp;DalMaso, M.,&nbsp;Lauri, A.,&nbsp;Kerminen, V.-M., &nbsp;Birmili, W., and&nbsp;McMurry, P.: Formation and growth rates of ultrafine atmospheric particles: a review of observations, J. Aerosol Sci., 35, 143–176, 2004. Kulmala, M., Riipinen, I., Nieminen, T., Hulkkonen, M., Sogacheva, L., Manninen, H. E., Paasonen, P., Pet{ä}j{ä}, T., Dal Maso, M., Aalto, P. P., Viljanen, A., Usoskin, I., Vainio, R., Mirme, S., Mirme, A., Minikin, A., Petzold, A., H�rrak, U., Pla{ß}-Dülmer, C., Birmili, W., and Kerminen, V.-M.: Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation, Atmos. Chem. Phys., 10, 1885–1898, <a href="http://dx.doi.org/10.5194/acp-10-1885-2010">https://doi.org/10.5194/acp-10-1885-2010</a>, 2010. Kupc, A.,&nbsp;Amorim, A.,&nbsp;Curtius, J.,&nbsp;Danielczok, A.,&nbsp;Duplissy, J.,&nbsp;Ehrhart, S., &nbsp;Walther, H.,&nbsp;Ickes, L.,&nbsp;Kirkby, J.,&nbsp;K{ü}rten, A.,&nbsp;Lima, J. M.,&nbsp;Mathot, S.,&nbsp;Minginette, P., &nbsp;Onnela, A.,&nbsp;Rondo, L., and&nbsp;Wagner, P.&nbsp;E.: A fibre-optic UV system for H<sub>2</sub>SO<sub>4</sub> production in aerosol chambers causing minimal thermal effects, J. Aerosol Sci., 42, 532–543, 2011. Launder, B. and&nbsp;Spalding, D.: The numerical computation of turbulent flows, Comput. Methods Appl. Mech. Eng., 3, 269–289, 1973. Lyman, W.&nbsp;J.,&nbsp;Reehl, W.&nbsp;F., and&nbsp;Rosenblatt, D.&nbsp;H.: Handbook of chemical property estimation methods, American Chemical Society: Washington, DC, USA, 1990. Marti, J.,&nbsp;Jefferson, A.,&nbsp;PingCai, X.,&nbsp;Richert, C.,&nbsp;McMurry, P., and &nbsp;Eisele, F.: H<sub>2</sub>SO<sub>4</sub> vapor pressure of sulfuric acid and ammonium sulfate solutions, J. Geophys. Res., 102, 3725–3735, 1997. McMurry, P.: Photochemical aerosol formation from so<sub>2</sub>: A theoretical analysis of smog chamber data, J. Colloid Interface Sci., 78, 513–527, 1980. Nieminen, T., Lehtinen, K. E. J., and Kulmala, M.: Sub-10 nm particle growth by vapor condensation � effects of vapor molecule size and particle thermal speed, Atmos. Chem. Phys., 10, 9773–9779, <a href="http://dx.doi.org/10.5194/acp-10-9773-2010">https://doi.org/10.5194/acp-10-9773-2010</a>, 2010. Riipinen, I., Sihto, S.-L., Kulmala, M., Arnold, F., Dal Maso, M., Birmili, W., Saarnio, K., Teinil{ä}, K., Kerminen, V.-M., Laaksonen, A., and Lehtinen, K. E. J.: Connections between atmospheric sulphuric acid and new particle formation during QUEST III-IV campaigns in Heidelberg and Hyytil{ä}l{ä}, Atmos. Chem. Phys., 7, 1899–1914, <a href="http://dx.doi.org/10.5194/acp-7-1899-2007">https://doi.org/10.5194/acp-7-1899-2007</a>, 2007. Sch{ü}tze, M. and&nbsp;Stratmann, F.: Numerical simulation of cloud droplet formation in a tank, Comput. Geosci., 34, 1034–1043, 2008. Seinfeld, J. and&nbsp;Pandis, S.: Atmospheric Chemistry and Physics: From air pollution to climate change, Wiley, New York, USA, 1997. Sihto, S.-L., Kulmala, M., Kerminen, V.-M., Dal Maso, M., Pet{ä}j{ä}, T., Riipinen, I., Korhonen, H., Arnold, F., Janson, R., Boy, M., Laaksonen, A., and Lehtinen, K. E. J.: Atmospheric sulphuric acid and aerosol formation: implications from atmospheric measurements for nucleation and early growth mechanisms, Atmos. Chem. Phys., 6, 4079–4091, <a href="http://dx.doi.org/10.5194/acp-6-4079-2006">https://doi.org/10.5194/acp-6-4079-2006</a>, 2006. Svensmark, H. and&nbsp;Friis-Christensen, E.: Variation of cosmic ray flux and global cloud coverage - a missing link in solar-climate relationships, J. Atm. Sol. Terr. Phys., 59, 1225–1232, 1997. Tabazadeh, A.,&nbsp;Toon, O.,&nbsp;Clegg, S., and&nbsp;Hamill, P.: A new parameterization of H<sub>2</sub>SO<sub>4</sub>/H<sub>2</sub>O aerosol composition: Atmospheric implications, Geophys. Res. Lett., 24, 1931–1934, 1997. Wilck, M.,&nbsp;Stratmann, F., and&nbsp;Whitby, E.: A fine particle model for fluent: Description and application, in Proc. Sixth Int. Aerosol Conf., pp. 1269–1270, Chinese Association for Aerosol Research in Taiwan/International Aerosol Research Assembly, Taipei, Taiwan, 2002. Wilke, C.&nbsp;R. and&nbsp;Lee, C.&nbsp;Y.: Estimation of Diffusion Coefficients for Gases and Vapors , Ind. Eng. Chem., 47, 1253–1257, 1955.