Are we reading what we’re referring to?

One rule one learns during university years is, that we should never list a reference we haven’t read and how simple this rule might be, it is strange that many researchers do not follow it. Or they read only the part, which is of interest to ones own work. This might have happened to Wilhelm Nusselts’ (1882-1957), German engineer and scientist, work. After him we named an important non-dimensional number, the Nusselt number, but it seems that one of his main ideas in his famous 1915 paper got lost. I remember from my physics classes at high school and university that there are three modes of heat transfer, namely heat conduction (Wärmeleitung), heat convection (Konvektion) and thermal radiation (Strahlung). This is also what is found in all heat transfer books I had so far, be it in English or in German, with one exception: This book, it is unfortunately only available in German, goes back to the often cited, but less read 1915 paper in which Nusselt (Nußelt) states:

It is often claimed in the literature, that heat transmission from a body be due to three reasons: the radiation, the conduction, and the convection. This subdivision of heat transmission in conduction and convection gives the impression as if we had to do with two independent phenomena. From this one had to conclude, that heat might also be transferred by convection without any contribution of conduction. This, however is not true.” Source

I like especially how he starts his sentence. “It is often claimed in the literature” is a timeless sentence. I could write the same sentence today almost a century later and it would still be up-to-date. I still haven’t managed to get hands on this paper, but I will try to ask some friends in Germany if they have access to this (for me rather) unknown Journal in which he published his ideas. Is there anyone out there who might have a copy of Nusselts 1915 paper?

W. Nusselt. Das Grundgesetz des Wärmeüberganges. Gesund. Ing, 1915.

P.S.: I started to think about this matter 2 years ago when I bought the book mentioned above, however I still haven’t completely convinced myself. I tried to ask few heat transfer experts, but also they didn’t know Nusselt aforementioned statement. Neither did they refuse it, nor did they accept it. Here I am as smart or stupid as before.

P.P.S.: Many thinks are just assumed in our daily live, or we just believe things, which are stated many times. Here lies a danger, more important than the modes of heat transfer. How often have I believed things I heard in the news or reported to me by friends. To go back to the roots (I didn’t came up with the word “roots” yesterday. Wurzel is such a simple German word for it :)) and check the content of the news reported is one of the tools we have to protect our selves from being fooled.


4 Responses to “Are we reading what we’re referring to?”

  1. 1 ferramis January 12, 2008 at 8:19 pm

    Hallo Achim,

    Ich bin eher Strömungsmechaniker und möchte mich ungern in philosophische Diskussionen einmischen. Praktisch gibt es hier wohl keinen nutzen, aber nichtsdestoweniger ist eine klare und rationale Definition in allen Bereichen erstrebenswert. Ähnliche Diskussionen erleben wir auch in der Turbulenzforschung, so zB Power vs. Log-law in Grenzschichten, der Einfluss der Initialconditions zB in Free shear flows usw. Ich habe seit meinem letzten Beitrag nicht weiter”geforscht” da meine Heat transfer Profs nicht an solch einer Diskussion interessiert waren. Nach deiner Erinnerung werde ich mich aber erneut mit diesem Thema beschäftigen. Wenn du überzeugende Argumente findest habe ich immer ein offenes Ohr. Bei einem Deutschlandbesuch werde ich mich mal nach der Suche nach der Orginalquelle begeben.

  2. 2 Achim January 12, 2008 at 8:53 pm

    das ging ja schnell. Vielen Dank für die Info.
    Also ich bin in der Zentralbibliothek der TU Berlin fündig geworden. Dort soll es auch den zitierten Aufsatz von 1915 geben … mal sehen.


  3. 3 ferramis January 12, 2008 at 9:19 pm


    Hier in Schweden konnte ich es nicht finden, und an meiner alten Uni in BRD fehlt gerade Vol 38, wo der Artikel enthalten sein soll. Falls du ihn finden solltest würde ich mich sehr über eine Kopie freuen.

  4. 4 Achim January 12, 2008 at 9:49 pm

    Mache ich gern. Aber erst einmal muss ich ihn in den Händen haben. Vorher glaube ich nicht, dass das so einfach geht (Erfahrung).

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