Wolfgang von Unesorge

Wolfgang Feodor Hermann Alfred Wilhelm von Ohnesorge (born September 8, 1901 in Potsdam , † May 26, 1976 in Cologne ) was a German mechanical engineer . The no-worries number is named after him, a key figure for assessing the influence of inertia, viscosity and surface tension when jets of liquid disintegrate.

biography

Wolfgang came from the noble family von Ohnesorge, who were wealthy near Posen . He was the second son of the German major general Feodor von Ohnesorge (1872-1926) and his wife Gertrud, née Moeller (* 1877).

Unesorge attended school in Poznan and the Roßleben convent school and originally wanted to study art history and music. Instead, he studied mechanical engineering at the Technical University of Charlottenburg from 1922 to 1927 (graduate engineer). After that he was briefly in industry and from 1928 assistant to Hermann Föttinger at the TH Charlottenburg. In 1936 he received his doctorate with a dissertation on high-speed recordings of the disintegration of liquid jets into drops ( application of a cinematographic high-frequency apparatus with mechanical control of the exposure to record the drop formation and the disintegration of liquid jets ). The dissertation required difficult experiments and therefore dragged on for several years. After that he originally wanted to work for Borsig , but during the economic crisis he only found a job in the calibration administration in Berlin and later in Reichenberg in Bohemia. During World War II he was a soldier in France and on the Eastern Front , where he was wounded. Most recently he was a lieutenant and was able to escape from Soviet captivity. He moved with his family to Cologne, where he was director of the regional authority of North Rhine-Westphalia from 1951 to 1966.

In 1951 he joined the Order of St. John , to which his father belonged, and in 1952 founded the St. John Aid Communities, which he headed until 1958. He later became honorary commander and head of the Johanniter in Cologne.

He is best known for his dissertation. In it he studied the flow of a liquid from a nozzle, varying the speed and type of the liquid. He was able to differentiate between four areas depending on the speed (see liquid jet ):

Slow dripping under the influence of gravity without jet formation
Decomposition of a cylindrical beam by axially symmetric perturbations according to Lord Rayleigh
Decomposition of the jet by wave-like (helical) disturbances (after A. Weber (experiment, 1931) and Haenlein (theory))
"Static" breakdown into drops

In order to distinguish between the various regimes, the Ohnesorge number (which can be expressed by the Weber and Reynolds numbers) has proven useful.

He had been married to Antonie von Stolberg-Wernigerode since 1929 (divorced in 1934) and had one daughter. In 1939 he married Siegrid von Bünau , with whom he had five children.

swell

Gareth H. McKinley, Michael Renardy: by Wolfgang von Ohnesorge, 2011 (pdf)

Individual evidence

^ Gothaisches genealogisches Taschenbuch der Briefadeligen houses 1907. First year, Justus Perthes, Gotha 1906, p. 596.
↑ Published as The Formation of Droplets from Nozzles and the Dissolution of Liquid Jets. ZAMM, Volume 16, 1936, pp. 355-358, also Z. VDI, Volume 81, 1937, pp. 465-466. The results were also presented at the 1936 GAMM conference.

personal data
SURNAME	No worries, Wolfgang von
BRIEF DESCRIPTION	German mechanical engineer
DATE OF BIRTH	September 8, 1901
PLACE OF BIRTH	Potsdam
DATE OF DEATH	May 26, 1976
Place of death	Cologne

[1] Gothaisches genealogisches Taschenbuch der Briefadeligen houses 1907. First year, Justus Perthes, Gotha 1906, p. 596.

[2] Published as The Formation of Droplets from Nozzles and the Dissolution of Liquid Jets. ZAMM, Volume 16, 1936, pp. 355-358, also Z. VDI, Volume 81, 1937, pp. 465-466. The results were also presented at the 1936 GAMM conference.