Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing...Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.展开更多
We examine the possibility of using alternative roads when confronted with traffic congestion. One is the main road; the second alternative is through a secondary road into which additional cars are coming. To keep th...We examine the possibility of using alternative roads when confronted with traffic congestion. One is the main road; the second alternative is through a secondary road into which additional cars are coming. To keep the total number of vehicles constant, we subtract on the main road the same number of cars as where added to the bypass. We check the Fourier transform of the average on each traffic light cycles of the velocity on the main road and bypass. In the jammed region we obtained different results for the main road and for the bypass. Whereas for the main road we obtained l/f, for the bypass we obtained ＂red noise＂, i.e., 1/f2.展开更多
文摘Pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow were experimentally evaluated. The authors considered liquid-cooling applications because there were few data available comparing to air-cooling applications. Empirical equations to predict heat transfer on the endwall were developed by obtaining experimental data on the copper base plate with acrylic pins. A new model for predicting pressure drops and heat transfer over staggered pin fin heat sinks with top bypass flow based on mass, momentum, and energy conservation within the two control volumes is proposed. The first control volume in the model is located within the finned area, and the second is located in the gap between the tip of the pins and the flow channel. This model combines two conditions according to the boundary-layer thickness. A comparison between experimental and calculated results revealed that dimensionless pressure drops and the Nusselt number could be predicted within 30% error for the former and 50% error for the latter.
文摘We examine the possibility of using alternative roads when confronted with traffic congestion. One is the main road; the second alternative is through a secondary road into which additional cars are coming. To keep the total number of vehicles constant, we subtract on the main road the same number of cars as where added to the bypass. We check the Fourier transform of the average on each traffic light cycles of the velocity on the main road and bypass. In the jammed region we obtained different results for the main road and for the bypass. Whereas for the main road we obtained l/f, for the bypass we obtained ＂red noise＂, i.e., 1/f2.
