Milton Plesset's oral history comments on cavitation

by Milton S. Plesset


From the Caltech Archives, the oral history of Milton S. Plesset, dated Dec.8, 1981:

Interviewer:: So you came back to Pasadena, then, and got a job with the Naval Ordnance Test Station?

PLESSET: Yes. Still in fluid mechanics.

Interviewer:: What was involved in that job?

PLESSET: Well, they had an office up on Green Street. And one thing that they were concerned about was the problem of water entry of torpedoes. They were still trying to drop torpedoes from airplanes, trying to shoot at ships. And often they would drop these torpedoes, and they would break up. They had to go very slowly. So an airplane would fly very slowly and steadily at low altitude. And here, the ship is shooting at them all the time. And most of them never made it. Then they had problems with torpedoes fired from submarines. Sometimes instead of going to the ship, it would come around and threaten to come back [laughter]. Things like that. So that the hydrodynamics of underwater bodies had some problems. And they were still working on the problems of water entry, dropping torpedoes from airplanes and so on.

Interviewer:: During that time, were you in touch with people at Caltech?

PLESSET: Yes, to some extent.

Interviewer:: And then you were hired by Caltech, as Associate Professor of Applied Mechanics.


Interviewer:: And DuBridge was thenÖ

PLESSET: He was president, yes. This was just about a year or two after he became president at Caltech.

Interviewer:: Did your contact with him lead to your being hired?

PLESSET: I donít know. Maybe [laughter]. Iíd like to give him the credit.

Interviewer:: Did you feel that the Institute was different when you came back and DuBridge was president?

PLESSET: Well, of course it was. It seemed very small when Millikan was running it. And it wasnít so small when I came backóat least it didnít seem to be so small; but still smaller than it is now. But DuBridge was very keen on maintaining a very high level of activity. He was always that way; he was that way at Rochester. So I think he did a lot to keep Caltech at a very elevated level of activity, particularly in research. It could have slid downhill, but it didnít. I think he did an awful lot in keeping Caltech just way up there, and through a difficult time when a lot of places were changing.

Interviewer:: Do you think the war left any lasting effects on the Institute?

PLESSET: Well, I hadnít thought about that. I think the war changed engineering quite a bit, and it changed it here at Caltech, too, because people became much more aware of what engineering and applied physics and applied science, what their capabilities were. So I think that that did make a change here at Caltech.

Interviewer:: You must have been dealing with different professors since your previous experience had been in the physics department.

PLESSET: Yes, it was a different group of people. They were also very stimulating.

Interviewer:: Is there anybody from that time who stands out in your mind?

PLESSET: Well, I didnít know very many of them in engineering. But one soon found out they were very smart people.

Interviewer:: It has been said that your favorite class to teach was classical theoretical physics. Would you agree?

PLESSET: [Laughter] Yes, thatís right.

Interviewer:: So, in some ways, your interests havenít changed all that much.

PLESSET: No, not really.

Interviewer:: Can you describe, then, from 1948 up to í51, when you became a full professor, what your experience was at Caltech? How you felt about your classes and the students.

PLESSET: Well, students that I ran into were just outstanding. They were so bright and so capable that it was scary at times [laughter]. Itís remarkable how they kept getting such good studentsóthese were graduate students for the most part, though I did have some undergraduates in some of the classes that Iíve taughtóthey were just awfully good. That was very stimulating, the teaching, because the students were so good.

Interviewer:: Were you pursuing any research in particular during these years?

PLESSET: Well, I got interested in this field of cavitation and the related effects. I wanted to understand it; and I think I did do some things that contributed to understanding it.

Interviewer:: Cavitation has to do with bubble-flow?

PLESSET: Well, it has to do with the formation of vapor cavities in a liquid flow. If the pressure falls, thereís a possibility that the liquid will boil at low temperature, thus cavitation. Boiling takes place because you lower the pressure, not because you raise the temperatureóitís a similar phenomenon, though.

Interviewer:: Did you have any specific applications in mind for the research you were doing?

PLESSET: Well, with the development of more efficient pumps, higher speed, you run into cavitation more, and have to be more concerned with it. So that was the application.

Last updated 2/16/07.

Christopher E. Brennen