GRAETZ

GERMANY (see also List of Individuals)

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26.9.1856 Breslau/PL - 12.11.1941 Munich/D

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Leo Graetz studied mathematics and physics at the Universities of Breslau, today's Wrocław in Poland, Berlin and Strasburg. From 1881 he was an assistant at Strasburg University and moved to Munich University in 1883 as a Lecturer in physics. He was promoted to associate professor in 1893 and to full professor of physics in 1908, besides Roentgen. Graetz was known for special lectures presented to medical students, and a laboratory in the university cellar is still called Graetzlabor.

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Graetz's scientific work was first concerned with heat conduction, radiation, elasticity and friction and after 1890 with problems of electromagnetic waves. He published twenty-three editions of his Electricity and its applications, and wrote a five volume work Handbook of electricity and magnetism. In hydrodynamics, the Graetz number relates to problems of heat flow through tubes, as a combination of the Prandtl and the Reynolds numbers. It is the ratio of the products of fluid density times velocity times cross-sectional tube area times the fluid heat capacity at constant pressure, divided by the product of the thermal conductivity times the tube length. Previously to this research topic he was interested in the vorticity of fluid flow related to incompressible and compressible fluids. Following the approach of Hermann von Helmholtz (1821-1894) he thus considered an inviscid fluid and was able to generalize some of Helmholtz's theorems.

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_{Anonymous (1926). Geheimrat Prof. Dr. Leo Graetz. Umschau 30: 808. P}

_{Gerlach, A. (1964). Graetz, Leo. Neue Deutsche Biographie 6: 718. Duncker&Humblot: Berlin.}

_{Graetz, L. (1879). Einige Sätze über Wirbelbewegungen in reibenden Flüssigkeiten. Zeitschrift für Mathematik und Physik 24: 239-244.}

_{Graetz, L. (1880). Über Wirbelbewegungen in compressiblen Flüssigkeiten Zeitschrift für Mathematik und Physik 25: 1-10.}

_{Graetz, L. (1883). Über die Wärmeleitungsfähigkeit von Flüssigkeiten. Annalen der Physik und Chemie Neue Folge 18: 79-94; 25: 337-357.}

_{Graetz, L. (1888). Über die Reibung von Flüssigkeiten. Annalen der Physik und Chemie Neue Folge 34: 25-39.}

_{Graetz, L., Stöckl, K. (1927). Reibung in Flüssigkeiten. Handbuch der physikalischen und technischen Mechanik 5: 392-472, F. Auerbach, W. Hort, eds. Barth: Leipzig.}

_{Poggendorff, J.C. (1898). Graetz, Leo. Biographisch-Literarisches Handwörterbuch 3: 540;}

_{4: 524; 5: 442-443; 6: 937. Barth: Leipzig, with bibliography. http://ichmt.me.metu.edu.tr/dimensionless/ P}