in?. 1. Hear Mass Transfer.

Vol. 1 I, pp. 3-S.

Pergamon Press 1968.

Printed in Great Britain

LLEWELLYN

M. K. BOELTER

1898-1966
R. A. SEBAN
M~hanic~ Engineering Department, College of En~n~~ng,
University of California, Berkeley, California(Received 16 June 19671

THE CAREERof Professor L. M. K. Boelter
reflected throughout his technical interests inheat transfer and thermodynamics, a devotion
to teaching, wide sociological interests, andleadership in educational administration. While
the record of his activities reveals a chronology inthe formalization of these interests, the older ofhis students remember that while the theme of
his instruction was technical, there was emphasis
too on the impact of technology on society andon the nature of education, Later students,
whose contact with him was more informal, areaware of his administrative efforts in maintaining synthesis in the diversely growing fieldof engineering and of his activity in relation tourban problems through a long membership on
the City of Los Angeles Planning Commission.
All of his students were permanently influenced
by instruction which centered on an awarenessof the learning process and the provision ofstimuli which aroused the highest achievementsof which they were capable. One does noteasily or briefly take the measure of such a man
and there are here cited only biographical details
and a review of his contributions to the field ofheat transfer, in which selected references havebeen chosen to indicate the scope and chronology of his interests and to recall some of hisstudents and co-workers.
Dean Boelter was born in Winona, Minnesota ;there and in the state of Washington he received
his early education. He matriculated at theUniversity of California at Berkeley in 1913,
received his bachelor’s degree in 1917, and theMaster’s degree in Electrical Engineering in
1919. Then with his appointment as Instructor
in Electrical Engineering began the uninterrupted, distinguished and loyal association as afaculty member of the University of California.
In 1923 he became Assistant Professor in theDepartment of Mechanical Engineering andhis interests in cooling problems in internal
combustion engines stimulated his initial workin heat transfer. He was advanced to Associate
Professor in 1927 and to the Professorship in1934. He was appointed Associate Dean ofEngineering at Berkeley in 1941 and delegatedto organize the College of En~neering at Los
Angeles, which began formally in 1944 withProfessor Boelter as Dean and so continued
until his retirement in 1965.
The rationalizationof the engine coolingsituation stimulated investigations of a varietyof associated heat-transfer problems and theinitial contributions thereto provided pioneering
insights into many areas, some of which arestill viable today. With Dittus [l], Professor
Boelter developed the correlation for the heattransfer coefficient for turbulent flow in tubes,
with Cherry [2], there was examined the heattransfer to viscous flow with variable viscosity,and with Martinelli [3], the effect of combined
free and forced convection in a vertical tube.
The analogy between heat transfer and friction
in turbulent flow was examined with ~artinelliand Jonassen [4], and the effect of vibration onfree convection from a horizontal cylinder wasdefined with Martinelli [5].

4

R. A. SEBAN

From 1919 to 1944 Professor Boelter directed
the testing agency of the California State
Division of Motor Vehicles, a service primarily
directed toward the testing of motor vehicle
lights and signalling devices, and this activityproduced an interest both in illumination andin the transmission of visible radiation. The
scattering of light by fog was considered with
Ryder [6]. This involvement with the radiation
problem was expanded by investigations in theagricultural area, in which the heating of citrus
orchards was an acute problem in the early
thirties. He demonstrated that the “smudge”
produced by the heating methods then in use
actually decreased the diurnal energy input tothe fruit. This work in the thermal radiation
area led to improved methods of shape factor
determination with Cherry [7], and the development of improved radiometers, with Gier [8],for the measurement of the radiation fromfruit, foliage and sky, with Brooks [9].
This activity focussed also on the orchardheater itself and stimulated studies on both
combustion in the heaters and on a piped fuelfeed system for them and it was the latter that
led to interest in the pressure drop associatedwith two phase flow in pipes. This investigation
led to pioneering papers with Kempner [lo] andwith Martinelli [ll], which with subsequent
papers defined the regimes of flow and presented a rational basis for the evaluation ofpressure drop for two-phase, gas-liquid flows.
The late thirties also involved a sharpening
interest in mass transfer, particularly associatedwith cooling tower performance and its prediction. The use of the enthalpy potential wasexploited, new data were developed with London [12], and the rate of water evaporation infree convection from horizontal surfaces wasalso examined with Gordon [13], as was thatfrom drops and sprays with Nottage [14].
The war years of 194145 saw Professor
Boelter in the direction of a substantial research
effort on various phases of aircraft heat transfer.
Internal flows were investigated further, particularly in respect to roughness, property varia-tion, and entry length, with Iversen [15].
External flow problems were considered withrespect to icing protection with Tribus [16] andthese considerations led to early examinationsof the effect of variable wall temperature on theheat transfer to boundary layer flows. Heat flow
meters were developed, using the plated thermopile, with Dunkle [17].
From 1928 through 1940, Professor Boelter
continuously conducted classes in heat transferat Berkeley and the early part of this period wasdevoted to an organization of knowledge in theform of class notes. In 1933, Cherry and Johnsonformalized this material, with their additions,
into the Heat Transfer Notes; these wereaugmented in several re-issues, with a final one,in which Martinelli participated,in 1941.
Readers experienced in the field from thethirties through the fifties will recall the tremendous impact of these Notes in teaching,research, and design. Though never prepared
as a text, they became the “bible” of their time
and their continued usefulness led to revisionand final publication [18] in 1965 by Johnson
and Dean Boelter.
As administrative
responsibilities accrued
and broader problems arose after 1955, Dean
Boelter’s direct involvement in heat-transfer
research diminished but his interest sustained
and made the Los Angeles campus a home andfocus for research in boiling, boundary-layer
heat transfer, thermal radiation and masstransfer. Without citing references specifically(for the names themselves define the efforts) hewas the aegis for much of the work of Tribus,
Bromberg, Poppendiek, Morrin, Gier, Edwards,and Knuth, who were attracted to the Los
Angeles campus by the environment he fosteredand the inspiration that he gave.
Beyond his direct personal contribution tothe field of heat transfer and the innumerable
indirect ones through his students, recognitionis due also to his organizational contributions.
He was one of the founders of the Heat Transfer
Division of the American Society of MechanicalEngineers and was Chairman thereof in 1938.

LLEWELLYN

M. K.

He was in 1948 a founder of the Heat Transfer
and Fluid Mechanics Institute and later sustained its spirit and insured its viability. He
encouraged the foundation of this Journal andremained a member of its Honorary Editorial
Advisory Board. He received the Max Jakob
Memorial Award in 1962 for his manifold
contributions to the field of heat transfer.
His distinction in the field of heat transfer has
been but partially d&ned here, much more has
been contributed by the students he taught andinspired and it is a characteristic of the man that
he was, that they recall him not first for technicalleadership but for humanity, sympathy, and aloyal, almost fatherly association that even
decades neither clouded or attenuated.

BOELTER

51898-1966

R. C. MARTINELLIand L. M. K. B~ELTER, Znt. Congr.

Appl. Mech. 578-585 (1938).
L. M. K. BoELTERand F. A. RYDER, Illurn. Engng 36 (3),223-235 (1940).
L. M. K. BOELTER,V. H. CHWRY and D. D. DAVIS,Zllum. Engng 34 (9), 1085 (1939).
J. T. GIN and L. M. K. B~ELTER, Temperature-Zts
Measurement and Control in Science and Industry.
p. 128. Reinhold, New York (1941).
9. L. M. K. BOELTER, F. A. BRINKS and C. LXXENZEN,

Bull. Am. Met. Sot. 20, 43-39(1939).

10. L. M. K. BOELTW and R. H. KEMPNER,Znd. Engng
Chem. 31.426-434 (1939).
11. L. M. K.. BOELTER,‘R. d. MARTINELLI,T. H. TAYLOR,
E. G. THOMSENand E. M. MORRIN, Trans. Am. Sot.
Engrs 66, 139-151 (1944).
12. A. L. LONWN, W. E. MACONand L. M. K. BOELTER,
Trans. Am. Sot. Mech. Engrs 63,41-50 (1940).
13. H. S. GORDON,J. R. GRIFFIN and L. M. K. BOELTER,Znd. Enann Chem. 38.59&600 (1946).
14. H. B. I?O~AGE and ‘L. M. K. BoEJ_&, Heat. Pip. Air

Condit. 12, 326333 (1940).
REFERENCES
1. F. W. Drrrus and L. M. K. BOELTW, Univ. C&fPubis

Engng 2 (13), 444461 (1930).

2. L. M. K. BOELTER. H. CHERRY. A. LEE and W. 0.
NELSON,Proceedings of the Fifth international Congress
on Applied Mechanics, pp. 571-578. John Wiley, NewYork (1938).
3. R. C. MARTINELLIand L. M. K. B~ELTER, Univ. Cal$Publs Engng 5 (2), 23-58 (1942).
4. L. M. K. BOELTER,R. C. MARTINELLIand F. JONASEN,Trans. Am. Sot. Mech. Engrs 63,447445 (1941).

15. L. M. K. BOELTER, G. YOUNG and H. W. IVERSEN,National Advisory Committee for Aeronautics, T.N.
1451 (1948).
16. M. TRIBUS, G. YOUNG and L. M. K. BOELTER,Trans.

Am. Sot. Mech. Engrs 70,977-982 (1948).
17. L. M. K. BOELTER,H. F. POPPENDIEK,R. V. DUNKLE
and J. T. GIER, National Advisory Committee forAeronautics, AAR 4107 (1944).
18. L. M. K. BOELTER.V. H. CHERRY. H. A. JOHNSONand
R. C. MARTINELLI,’Heat Transfer Notes. McGraw-Hill,
New York (1965).