A tribute to the memory of Prof. Yasutaka NAGANO
Professor Nagano, the former chair of theJSME Thermal Engineering Division, passed
away at the age of 71 on June 6, 2015. We
shall always remember him, his gentle smileand his excellent contribution to the studiesof turbulent heat transfer, e.g., turbulencemeasurement using hot- and cold-wire
techniques, two-equation turbulencemodeling and direct numerical simulations.

THMT‐5 at Dubrovnik
on September 29, 2006

Main achievements
Simultaneous measurement of velocity and temperature fluctuations

Analog circuit for simultaneous
measurement of velocity andtemperature fluctuations (JHT, 1978)

Instantaneous velocity vectors andtemperature fluctuations measured bymulti-wire probe composed ofsubmicron cold-wires (IJHFF, 2008)

Reynolds shear stress andturbulent heat fluxes in naturalconvection TBL (IJHMT, 1988)

Accurate prediction of complex turbulent heat transfer by the two-equation model• Two-equation model for heat transfer Äuj í= ãt

The eddy diffusivity for heat is modeled using thetime scale ratio R (see the left column) without using
the turbulent Prandtl number. This novel formulation
at the two-equation level not only increases theuniversality of numerical calculation of turbulent
heat transfer but also provides reliable predictionsof the variance of temperature fluctuations.

@Ç@xj• Modeling of eddy diffusivity for heat ãt = Cïfï(k 2 =")f (R)Pr ú 1yPr ù 1Pr = 1Pr ú 1R=úíkí="í=
úuk="Velocity boundary layer

Pr = 1éétPr ù 1

Thermal boundary layers

What about the turbulent Prandtl number?
Predictions of various Prandtl number fluids (PF, 1996)

Detailed understanding of turbulent heat transfer by DNS
Direct numerical simulation (DNS) enables us to elucidateturbulent heat transfer phenomena in the vicinity of the wall.
150
Case 1, H=2D
Case 2, H=D
Case 3, H=0.5DExp. (Ichimiya et al.)
H=D, Re=10000

Nu

100
5000

DNS based on the finite-difference method forthermally-stratified turbulent boundary layerover a 2-dimensional hill (ICJWSF, 2013)

Re=2VmD=ó=9120
Secondary maxima in Nu

24x/D

DNS for turbulent heat transfer inplane impinging jet (IJHFF, 2004)

6Streamwise averaged velocity
vectors and temperaturefluctuations in non-rotating/rotating channel flows by DNSof spectral method (JoT, 2003)

Professor Yasutaka Nagano---- Main research fields and key achievements ---I. Experimental Investigation of Turbulent Transport Phenomena

Hishida, M. and Nagano, Y. (1978). Simultaneous measurements of velocity and temperature innonisothermal flows. J. Heat Transfer, 100 (2), 340-345.
Hishida, M. and Nagano, Y. (1979). Structure of turbulent velocity and temperature fluctuations in fully
developed pipe flow. J. Heat Transfer, 101 (1), 15-22.
Hishida, M. and Nagano, Y. (1988). Turbulence measurements with symmetrically bent V-shaped hotwires. Part 1: principles of operation. J. Fluids Engng., 110 (3), 264-269.
Nagano, Y. and Tagawa, M. (1988). Statistical characteristics of wall turbulence with a passive scalar.
J. Fluid Mech., 196, 157-185.
Tsuji, T. and Nagano, Y. (1988). Characteristics of a turbulent natural convection boundary layer along avertical flat plate. Int. J. Heat Mass Transfer, 31 (8), 1723-1734.
Tsuji, T. and Nagano, Y. (1988). Turbulence measurements in a natural convection boundary layer along
a vertical flat plate. Int. J. Heat Mass Transfer, 31 (10), 2101-2111.
Tsuji, T. Nagano, Y., and Tagawa, M. (1992). Frequency response and instantaneous temperature profileof cold-wire sensors for fluid temperature fluctuation measurements. Exp. Fluids, 13 (2-3), 171178.
Nagano, Y., Tagawa, M. and Tsuji, T. (1993). Effects of adverse pressure gradients on mean flows andturbulence statistics in a boundary layer. In Turbulent Shear Flows 8 (pp. 7-21). Springer.
Nagano, Y. and Tsuji, T. (1994). Recent developments in hot- and cold-wire techniques for measurements
in turbulent shear flows near walls. Exp. Therm. Fluid Sci., 9 (2), 94-110.
Nagano, Y. and Tagawa, M. (1995). Coherent motions and heat transfer in a wall turbulent shear flow.
J. Fluid Mech., 305, 127-157.
Nagano, Y., Tsuji, T. and Houra, T. (1998). Structure of turbulent boundary layer subjected to adverse
pressure gradient. Int. J. Heat Fluid Flow, 19 (5), 563-572.
Houra, T. and Nagano, Y. (2008). Spatio-temporal turbulent structures of thermal boundary layer
subjected to non-equilibrium adverse pressure gradient. Int. J. Heat Fluid Flow, 29 (3), 591-601.

II. Modeling of Turbulent Heat and Momentum Transfer

Nagano, Y. and Hishida, M. (1987). Improved form of the k- model for wall turbulent shear flows.
J. Fluids Engng., 109 (2), 156-160.
Nagano, Y. and Kim, C. (1988). A two-equation model for heat transport in wall turbulent shear flows.
J. Heat Transfer, 110 (3), 583-589.
Nagano, Y. and Tagawa, M. (1990). An improved k- model for boundary layer flows. J. Fluids Engng.,
112 (1), 33-39.
Nagano, Y. and Tagawa, M. (1990). A structural turbulence model for triple products of velocity and scalar.
J. Fluid Mech., 215, 639-657.
Abe, K., Kondoh T., and Nagano, Y. (1994). A new turbulence model for predicting fluid flow and heattransfer in separating and reattaching flows—I. Flow field calculations. Int. J. Heat Mass Transfer,
37 (1), 139-151.
Abe, K., Kondoh, T. and Nagano, Y. (1995). A new turbulence model for predicting fluid flow and heattransfer in separating and reattaching flows—II. Thermal field calculations. Int. J. Heat Mass
Transfer, 38 (8), 1467-1481.
Nagano, Y. and Shimada, M. (1996). Development of a two-equation heat transfer model based on direct
simulations of turbulent flows with different Prandtl numbers. Phys. Fluids, 8 (12), 3379-3402.

III. DNS and LES of Turbulent Heat and Fluid Flows

Matsumoto, A., Nagano, Y. and Tsuji, T. (1991). Direct numerical simulation of homogeneous turbulent
shear flow. In 5th Numerical Fluid Dynamics Symp. (Vol. 1, pp. 361-364).
Iida, O. and Nagano, Y. (1999). Coherent structure and heat transfer in geostrophic flow under density
stratification. Phys. Fluids, 11 (2), 368-377.
Hattori, H. and Nagano, Y. (2004). Direct numerical simulation of turbulent heat transfer in plane
impinging jet. Int. J. Heat Fluid Flow, 25 (5), 749-758.
Nagano, Y., Hattori, H. and Houra, T. (2004). DNS of velocity and thermal fields in turbulent channel
flow with transverse-rib roughness. Int. J. Heat Fluid Flow, 25 (3), 393-403.
Inagaki, M., Kondoh, T. and Nagano, Y. (2005). A mixed-time-scale SGS model with fixed modelparameters for practical LES. J. Fluids Engng., 127 (1), 1-13.
Hattori, H., Houra, T. and Nagano, Y. (2007). Direct numerical simulation of stable and unstable turbulent
thermal boundary layers. Int. J. Heat Fluid Flow, 28 (6), 1262-1271.