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Full-Text Articles in Engineering
Direct Numerical Simulation Of Turbulent Katabatic Slope Flows With An Immersed-Boundary Method, Clancy Umphrey, Ray Deleon, Inanc Senocak
Direct Numerical Simulation Of Turbulent Katabatic Slope Flows With An Immersed-Boundary Method, Clancy Umphrey, Ray Deleon, Inanc Senocak
Inanc Senocak
We investigate a Cartesian-mesh immersed-boundary formulation within an incompressible flow solver to simulate laminar and turbulent katabatic slope flows. As a proof-of-concept study, we consider four different immersed-boundary reconstruction schemes for imposing a Neumann-type boundary condition on the buoyancy field. Prandtl’s laminar solution is used to demonstrate the second-order accuracy of the numerical solutions globally. Direct numerical simulation of a turbulent katabatic flow is then performed to investigate the applicability of the proposed schemes in the turbulent regime by analyzing both first- and second-order statistics of turbulence. First-order statistics show that turbulent katabatic flow simulations are noticeably sensitive to the …
Near-Wall Measurements For A Turbulent Impinging Slot Jet System, Jiang Zhe, Vijay Modi
Near-Wall Measurements For A Turbulent Impinging Slot Jet System, Jiang Zhe, Vijay Modi
Dr. Jiang Zhe
The velocity field in the vicinity of a target surface with a turbulent slot jet impinging normally on it is examined. The impingement region is confined by means of a confinement plate that is flush with the slot and parallel to the impingement plate. The distance H of the impingement wall from the slot is varied from 2 to 9.2 slot widths. Jet Reynolds numbers (based on slot width B) of 10,000–30,000 are considered. Mean velocity and root mean square velocity measurements are carried out using hot-wire anemometry. A boundary layer probe is utilized in order to obtain measurements at …
A Lagrangian Stochastic Model For Dispersion In Stratified Turbulence, S. K. Das, Paul A. Durbin
A Lagrangian Stochastic Model For Dispersion In Stratified Turbulence, S. K. Das, Paul A. Durbin
Paul A. Durbin
In this paper we discuss the development of a Lagrangian stochastic model (LSM) for turbulent dispersion of a scalar (species). Given any tensorally linear second-moment closure (SMC) turbulence model we show how to derive a mathematically equivalent set of stochastic differential equations (SDEs), i.e., the second-moment equations constructed from these SDEs are exactly the same (within a realizability constraint) as the given SMC. This set of equations forms the LSM. Both turbulence anisotropy and buoyancy effects are incorporated by this method. In order to achieve the correct critical Richardson number and to obtain the simplest Lagrangian formulation, a revised set …
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
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 …