Microstructure – Diffusion
Contact person: Dr. rer. nat. Anastasia August
Research
The research activities of the research group “Microstructure - Diffusion” include the modelling of liquid and solid foams as well as the simulative investigation of heat transport in porous structures, which, among other things, is influenced by fluid flow.
The improvement of the efficiency of heat exchangers, heat collectors and heat storage systems, in dependence of the microstructure and the material properties, is the objective of the work. During the reproduction of the processes, the phase transformation processes of the fluid medium are considered. The work of the research group focuses on the development of an optimal structure of the participating porous materials, such as the structure of a metal foam.
Metal Foams
Metal foams are materials with excellent properties. They look like beer froth, but without the beer, and basically without partitions between the individual bubbles. Only where three or more bubbles meet is it that material still does exist. These so-called ligaments form an irregular solid mesh, which still possesses many properties of the base material – metal: thermal conductivity, stability, electrical conductivity and even more properties, such as the lightness, the reduced demand for base material and especially the large surface, compared to the volume. This surface, for example, enables the heat to be exchanged by the air surrounding the ligaments. Because of this property, in connection with the good thermal conductivity of metal, metal foams are extremely popular in our research within the KIT programme ''Energy Efficiency, Materials and Resources''.
Solar Thermal Energy
Black objects can absorb solar energy extremely well. The skin of a polar bear is black, so that it is able to absorb as much energy as possible from the sunlight at the north pole. The white hairs of its fur, which allow the sunlight to pass through, are used to isolate the polar bear's own body heat. On the basis of this principle, heat collectors, consisting of textile spacer fabrics, were developed in the project “Solar Thermal Energy”, in cooperation with the Institute of Textile Technology and Process Engineering, Denkendorf, the project partner. Besides the generation of energy, the storage of energy does, of course, also play an important role. In the second part of the project, new storage systems were examined: small, thimble-sized buckets, filled with paraffin, which were positioned directly beneath the textile collector. During melting, paraffin stores the latent heat and releases it again during solidification. At the CMS, we examine the eligible systems by means of computer simulations and make suggestions for improvement, regarding their geometry.
Porous Water Pipes
Using energy resources in the most efficient manner is an important challenge of the future. In materials sciences, this results in a search for efficient, affordable and practical materials, for heat conduction and storage. Metal foams provide a promising solution for energy transmission and energy storage problems, as they possess both the capacity to allow fluids to permeate and a large surface. This enables fluids and other possible fillings to be heated more efficiently.
Hereby, the objective is to achieve a heat transfer, which is as high as possible, while, at the same time, the pressure drop is as low as possible. First, these foams are designed in computer simulations, in which the material is tested for different conditions, such as changes in temperature or pressure, as well as for the influence of different pore sizes. Subsequently, a 3D printer is used to produce a model for the investment casting of the optimal foam.
Metal foams are used, for example, in the design of water pipes that release their energy into the water more efficiently.
InSeL
The InSeL research project (innovative foam structures for an efficient lightweight design) is a research initiative in Baden-Wuerttemberg, concerned with research on lightweight design, which consists of an association of different universities, extramural institutions and companies, in which the IAM of the KIT is involved. It includes joint research, but also the communication of research results to companies, as well as the networking of the members of the InSeL project with other research projects.
At the CMS, we participate in the project by performing computer simulations in the field of liquid lather and solid polymer foams, which serve as preforms during the casting of particularly fine-pored and monodisperse metal foams.
The mechanical properties of the metallic lightweight tools, developed in this way, are examined by us, using computer simulations.
PoroSan
Even granules, such as soil materials, are porous media. They are contaminated and should be cleaned using flowing media. Therefore, understanding the flow and mass transfer properties of these media is of great importance. By simulating the flow of spheres, we try to get to the bottom of these phenomena.
Reder, M.; Holland-Cunz, J.; Lorson, P.; August, A.; Nestler, B.
2023. Advanced Engineering Materials. doi:10.1002/adem.202300340
Jamshidi, F.; Kunz, W.; Altschuh, P.; Lu, T.; Laqua, M.; August, A.; Löffler, F.; Selzer, M.; Nestler, B.
2023. Materials Today Communications, 34, Art.-Nr.: 105413. doi:10.1016/j.mtcomm.2023.105413
Holland-Cunz, J.; Laqua, M.; Wagner, F. N. P. H.; August, A.; Nestler, B.
2023. Forschung aktuell / Hochschule Karlsruhe
Holland-Cunz, J.; August, A.; Reder, M.; Nestler, B.
2022. Forschung aktuell, 2022 (Juni), 16–19
Kneer, A.; August, A.; Wirtz, M.; Herrmann, C.; Schneider, D.; Nestler, B.
2021. Forschung aktuell, 44–51
August, A.; Jamshidi, F.; Kneer, A.; Wolf, R. H.; Wirtz, M.; Nestler, B.
2020. International journal of heat and mass transfer, 159, Article No.: 120071. doi:10.1016/j.ijheatmasstransfer.2020.120071
August, A.; Nestler, B.
2020. Engineering Research Express, 2 (2), Art. Nr.: 025029. doi:10.1088/2631-8695/ab8c94
August, A.; Nestler, B.
2020. Engineering Research Express, 2 (1), Article No.015021. doi:10.1088/2631-8695/ab6ac6
Kneer, A.; Wirtz, M.; Yurtsever-Kneer, S.; Barbe, S.; August, A.
2019. Galvanotechnik, 2019 (4), 712–719
August, A.; Kneer, A.; Reiter, A.; Wirtz, M.; Sarsour, J.; Stegmaier, T.; Barbe, S.; Gresser, G. T.; Nestler, B.
2019. Energy, 168, 1017–1030. doi:10.1016/j.energy.2018.11.143
August, A.; Reiter, A.; Kneer, A.; Selzer, M.; Nestler, B.
2018. Heat and Mass Transfer Research Journal, 2 (1), 33–45
August, A.; Kneer, A.; Nestler, B.
2018. Forschung aktuell, 2018 (März), 56–58
Nestler, B.; August, A.; Selzer, M.; Hötzer, J.; Kellner, M.; Prajapati, N.; Rehn, V.; Seiz, M.
2018. Ceramic applications, 6 (1), 73–77
August, A.; Matz, A. M.; Mocker, B. S.; Heimann, J.; Nestler, B.; Jost, N.; Krug, P.
2017. Horizonte, 49, 3–5
August, A.; Matz, A. M.; Nestler, B.; Jost, N.
2016. Multidiscipline modeling in materials and structures, 12 (4). doi:10.1108/MMMS-03-2016-0012
August, A.
2015. Nachwuchsakademie ’Analyse und Bewertung von Eigenspannungen auf unterschiedlichen Längenskalen’, Kassel, 24.-28.Mai 2010
Jainta, M.; Reiter, A.; August, A.; Moik, F.; Nestler, B.
2015. Forschung aktuell, 2015, 13–15
August, A.; Nestler, B.; Kneer, A.
2015. Horizonte : Forschung an Fachhochschulen in Baden-Württemberg, (45), 68
August, A.; Ettrich, J.; Rölle, M.; Schmid, S.; Berghoff, M.; Selzer, M.; Nestler, B.
2015. International Journal of Heat and Mass Transfer, 84, 800–808. doi:10.1016/j.ijheatmasstransfer.2015.01.052
Hötzer, J.; Jainta, M.; Vondrous, A.; Ettrich, J.; August, A.; Stubenvoll, D.; Reichardt, M.; Selzer, M.; Nestler, B.
2015. High Performance Computing in Science and Engineering ’14 : Transactions of the High Performance Computing Center, Stuttgart (HLRS), 2014. Hrsg.: W. E. Nagel, 629–644, Springer. doi:10.1007/978-3-319-10810-0_41
Ettrich, J.; August, A.; Roelle, M.; Nestler, B.
2014. Cellular Materials (CellMAT 2014), Dresden, October 22-24, 2014
Ettrich, J.; August, A.; Nestler, B.
2014. Cellular Materials (CellMAT 2014), Dresden, October 22-24, 2014
August, A.; Kneer, A.; Janßen-Tapken, K.; Nestler, B.
2014. Cellular Materials (CellMAT 2014), Dresden, October 22-24, 2014
Ettrich, J.; August, A.; Roelle, M.; Nestler, B.
2014. Cellular Materials (CellMAT 2014), Dresden, 22.-24. Oktober 2014, CD-ROM
Ettrich, J.; August, A.; Nestler, B.
2014. Cellular Materials (CellMAT 2014), Dresden, 22.-24. Oktober 2014, CD-ROM
Wesner, E.; August, A.; Nestler, B.
2014. Horizonte : Forschung an Fachhochschulen in Baden-Württemberg, (43), 29–31
Ettrich, J.; Choudhury, A.; Tschukin, O.; Schoof, E.; August, A.; Nestler, B.
2014. Modelling and simulation in materials science and engineering, 22 (8), Art.Nr. 085006/1–29. doi:10.1088/0965-0393/22/8/085006
Kneer, A.; Janssen-Tapken, K.; Reimann, K.; August, A.; Nestler, B.
2013. 5th International Conference on Computational Methods for Coupled Problems in Sciennce and Engineering, Santa Eulalia, Ibiza, E, June 17-19, 2013
Kneer, A.; August, A.; Nestler, B.; Martens, E.
2013. 2nd International Conference on Materials for Energy (EnMat 2013), Karlsruhe, 12.-16. Mai 2013
August, A.; Nestler, B.; Rölle, M.; Schmid, S.; Ettrich, J.
2013. 2nd International Conference on Materials for Energy (EnMat 2013), Karlsruhe, 12.-16. Mai 2013
Römmelt, M.; August, A.; Kneer, A.; Stegmaier, T.; Nestler, B.
2012. Forschung aktuell, 2012, 21–24
August, A.
2012. Nachwuchsakademie ’Analyse und Bewertung von Eigenspannungen auf unterschiedlichen Längenskalen’, Kassel, 23.-24.April 2012
August, A.; Nestler, B.; Rölle, M.; Schmid, S.; Ettrich, J.
2012. Biannual Internat.Conf.on Materials Science Engineering (MSE 2012), Darmstadt, September 25-27, 2012
Schoof, E.; Römmelt, M.; Selzer, M.; August, A.; Nestler, B.; Kneer, A.; Stegmaier, T.
2012. International School and Conference on Biological Materials Science, Potsdam, March 20-23, 2012
Wesner, E.; Choudhury, A.; August, A.; Berghoff, M.; Nestler, B.
2012. Journal of crystal growth, 359 (1), 107–121. doi:10.1016/j.jcrysgro.2012.08.036
Vondrous, A.; Nestler, B.; August, A.; Wesner, E.; Choudhury, A.; Hötzer, J.
2012. High performance computing in science and engineering ’ 11 : transactions of the High Performance Computing Center, Stuttgart (HLRS) 2011. Ed.: W.E. Nagel, 595–606, Springer Verlag. doi:10.1007/978-3-642-23869-7_43
Choudhury, A.; Reuther, K.; Wesner, E.; August, A.; Nestler, B.; Rettenmayr, M.
2012. Computational materials science, 55, 263–268. doi:10.1016/j.commatsci.2011.12.019
Vondrous, A.; Nestler, B.; August, A.; Wesner, E.; Choudhury, A.; Hötzer, J.
2011. High Performance Computing in Science and Engineering, Stuttgart, October 4-5, 2011
August, A.
2011. Euromat 2011 : European Congress and Exhibition on Advanced Materials and Processes, Montpellier, F, September 12-15, 2011
August, A.
2011. Materials Research Society Spring Meeting, San Francisco, Calif., April 25-29, 2011
Wesner, E.; Choudhury, A.; August, A.; Berghoff, M.; Nestler, B.
2011. Euromat 2011 : European Congress and Exhibition on Advanced Materials and Processes, Montpellier, F, September 12-15, 2011
Rölle, M.; August, A.; Selzer, M.; Nestler, B.
2011. Forschung aktuell, 2011, 21–23
Römmelt, M.; August, A.; Nestler, B.; Kneer, A.
2011. 5th Internat.Conf.on Textile Composites and Inflatable Structures (Structural Membranes 2011), Barcelona, E, October 5-7, 2011
Römmelt, M.; August, A.; Nestler, B.; Kneer, A.
2011. 5th Internat.Conf.on Textile Composites and Inflatable Structures (Structural Membranes 2011), Barcelona, E, October 5-7, 2011. Ed.: E. Onate, 614–626
August, A.; Nestler, B.; Kneer, A.; Wendler, F.; Rölle, M.; Selzer, M.
2011. Werkstoffe in der Fertigung, 2011 (6), 45–46
August, A.; Nestler, B.; Wendler, F.; Selzer, M.; Kneer, A.; Martens, E.
2010. CELLMAT 2010 : Proceedings of the International Conference on Cellular Materials, Dresden, Germany, October 27 - 29, 2010. Ed.: G. Stephan, 148–151, Fraunhofer Institute for Manufacturing Technology and Advanced Materials
August, A.; Nestler, B.; Wendler, F.; Selzer, M.; Kneer, A.; Martens, E.
2010. Gumbsch, P. [Hrsg.] Proc.of the 5th Internat.Conf.on Multiscale Materials Modeling (MMM 2010), Freiburg, October 4-8, 2010 Stuttgart : Fraunhofer Verl., 2010, 355–358
August, A.
2010. International Conference on Cellular Materials (CellMat 2010), Dresden, October 27-29, 2010
August, A.
2010. Nachwuchsakademie ’Analyse und Bewertung von Eigenspannungen auf unterschiedlichen Längenskalen’, Kassel, 15.Oktober 2010
August, A.; Nestler, B.; Wendler, F.; Selzer, M.; Kneer, A.; Martens, E.
2010. 5th Internat.Conf.on Multiscale Materials Modeling (MMM 2010), Freiburg, October 4-8, 2010
August, A.
2007. Universität Karlsruhe (TH). doi:10.5445/IR/1000007160