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The Fokker–Planck Closure For Turbulent Molecular Mixing: Passive Scalars, Rodney O. Fox Jun 1992

The Fokker–Planck Closure For Turbulent Molecular Mixing: Passive Scalars, Rodney O. Fox

Rodney O. Fox

A turbulent-molecular-mixing closure for passive scalar mixing is derived based on the theory of diffusion in layerlike lamellar structures. The closure is formulated in terms of the Fokker- Planck (FP) equation (or an equivalent stochastic differential equation), and is to be employed in conjunction with the probability density function (pdf) balance equation appearing in the pdf methods for modeling turbulent reactive flows. Like the mapping closure, the FP closure predicts a limiting Gaussian pdf for the passive scalar concentration in isotropic turbulence. In addition, the FP closure models the joint pdf of the scalar concentration and the scalar gradient and ...


Liquid Immersion Cooling Of A Longitudinal Array Of Discrete Heat Sources In Protruding Substrates: Ii—Forced Convection Boiling, Theodore J. Heindel, S. Ramadhyani, F. P. Incropera Mar 1992

Liquid Immersion Cooling Of A Longitudinal Array Of Discrete Heat Sources In Protruding Substrates: Ii—Forced Convection Boiling, Theodore J. Heindel, S. Ramadhyani, F. P. Incropera

Theodore J. Heindel

Forced convection boiling experiments have been performed for an in-line 1 x 10 array of discrete heat sources, flush mounted to protruding substrates located on the bottom wall of a horizontal flow channel. FC-72, a dielectric fluorocarbon liquid, was used as the heat transfer fluid, and the experiments covered a range of flow velocities, degrees of fluid subcooling, and channel heights. The maximum heater-to-heater surface temperature variation was less than 2.5°C and was insensitive to channel height under conditions of fully developed nucleate boiling. Although the fluid velocity influenced the heat flux for partially developed nucleate boiling, its ...


Liquid Immersion Cooling Of A Longitudinal Array Of Discrete Heat Sources In Protruding Substrates: I—Single-Phase Convection, Theodore J. Heindel, F. P. Incropera, S. Ramadhyani Mar 1992

Liquid Immersion Cooling Of A Longitudinal Array Of Discrete Heat Sources In Protruding Substrates: I—Single-Phase Convection, Theodore J. Heindel, F. P. Incropera, S. Ramadhyani

Theodore J. Heindel

Experiments have been performed using water and FC-77 to investigate heat transfer from an in-line 1 x 10 array of discrete heat sources, flush mounted to protruding substrates located on the bottom wall of a horizontal flow channel. The data encompass flow regimes ranging from mixed convection to laminar and turbulent forced convection. Buoyancy-induced secondary flows enhanced heat transfer at downstream heater locations and provided heat transfer coefficients comparable to upstream values. Upstream heating extended enhancement on the downstream heaters to larger Reynolds numbers. Higher Prandtl number fluids also extended heat transfer enhancement to larger Reynolds numbers, while a reduction ...