A large-eddy simulation (LES) is performed in order to predict the mean velocity field, the turbulence characteristics and the heat transfer rate of an impinging jet in cross-flow configuration on a heated wall-mounted cube. The WALE model was used to model the subgrid-scale tensor. The results from the LES are compared with a Reynolds stress model (RSM) and against earlier measurements with identical set-up. A comparison between the results from the predictions and the measurements shows that in general the LES has better agreement with the measurements compared to the RSM and particularly in the stagnation region of the impinging jet. (C) 2008 Elsevier Ltd. All rights reserved.

The objective of this study is to investigate the thermal performance and the cost measured in pressure drops of a targeted cooling system with use of an impinging jet in combination with a low-velocity channel flow on a heated wall-mounted cube. The effects of the Reynolds numbers of the impinging jet and the cross flow, as well as the distance between the top and bottom plates, are investigated. A steady-state 3D computational fluid dynamics model was developed with use of a Reynolds stress model as turbulence model. The geometrical case is a channel with a heated cube in the middle of the base plate and two inlets, one horizontal channel flow and one vertical impinging jet. The numerical model was validated against experimental data with a similar geometrical setup. The velocity field was measured by particle image velocimetry and the surface temperature was measured by an infrared imaging system. This case results in a very complex flow structure where several flow-related phenomena influence the heat transfer rate and the pressure drops. The average heat transfer coefficients on each side of the cube and the pressure loss coefficients are presented; correlations for the average heat transfer coefficient on the cube and the pressure loss coefficients are created. [DOI: 10.1115/1.2969266]

The current trends of electronic devices are resulting in a steady increase in the dissipated heat from the components. One possible cooling method is to use an impinging jet and a low-velocity channel flow. The objective is to investigate the performance of the v(2) - f model and RSM in order to predict the time-average velocity and the Reynolds stresses. The case is a channel with a cube in the middle of the base plate and two inlets, one horizontal channel flow and one vertical impinging jet above the cube. The turbulence models are validated against earlier PIV measurement with identical set-up.

The current trends toward the greater functionality of electronic devices are resulting in a steady increase in the amount of heat dissipated from electronic components. Forced channel flow is frequently used to remove heat at the walls of the channel where a PCB with a few high heat dissipating components is located. The overall cooling strategy thus must not only match the overall power dissipation load, but also address the requirements of the "hot" components. In order to cool the thermal load with forced channel flow, excessive flow rates will be required. The objective of this study is to investigate if targeted cooling systems, i.e., an impinging jet in combination with a low velocity channel flow, can improve the thermal performance of the system. The steady-state three-dimensional (3-D) model is developed with the Reynolds-Stress-Model (RSM) as a turbulence model. The geometrical case is a channel with a heated cube in the middle of the base plate and two inlets, one horizontal channel flow, and one vertical impinging jet. The numerical model is validated against experimental data obtained from three well-known cases, two cases with an impinging jet on a flat heated plate, and one case with a heated cube in a single channel flow. The effects of the jet Re and jet to-cross-flow velocity ratio are investigated. The airflow pattern around the cube and the surface temperature of the cube as well as the mean values and local distributions of the heat transfer coefficient are presented.