Thermal Characterization of Multiple Micro-Jet Impingement Cooling Model

2014 ◽  
Author(s):  
Afzal Husain ◽  
Jun-Hee Kim ◽  
Kwang-Yong Kim
Keyword(s):  
Laminar Flow ◽  
Heat Sink ◽  
Jet Impingement ◽  
Low Flow ◽  
Design Parameters ◽  
Computational Domain ◽  
Flow Conditions ◽  
Excessive Pressure ◽  
Impingement Cooling ◽  
Laminar Flow Conditions

The present study investigated thermal performance of silicon-based multiple micro-jet impingement cooling heat sink for thermal management of electronics. Three-dimensional numerical analysis was performed for steady incompressible laminar flow and conjugate heat transfer through a finite volume solver. A heat flux of 100 W/cm2 was applied at one side of the silicon substrate, while at the other side jet impingement system was designed. The jet plate was consisted of many jet holes whereas computational domain was simplified by utilizing symmetric boundary conditions along the flow as well as lateral directions. The effect of various design parameters, namely, jet diameter, jet pitch, standoff (distance from jet exit to impingement surface) etc., have been analyzed at jet Reynolds numbers 100, 200 and 300 under laminar flow conditions. In view of the low pumping powers available through micro-pumping systems, low flow rates were applied for the analysis. The cross-flow effects of the spent-flow were investigated for finding out optimum design parameters and flow conditions for the heat sink. The temperature distribution was discussed for various values of jet diameter, standoff and jet-to-jet spacing. While a moderate thermal resistance of the heat sink was obtained under laminar flow conditions, high performance can be achieved for higher flow-rate turbulent flow conditions at the expense of excessive pressure-drop which would be investigated in future studies.

Thermal Performance of a Silicon-Based Multiple Micro-Jet Impingement Heat Sink

2013 ◽  
Author(s):  
Afzal Husain ◽  
Jun-Hee Kim ◽  
Kwang-Yong Kim
Keyword(s):  
Laminar Flow ◽  
Thermal Performance ◽  
Heat Sink ◽  
Jet Impingement ◽  
Low Flow ◽  
Design Parameters ◽  
Computational Domain ◽  
Flow Conditions ◽  
Silicon Based ◽  
Laminar Flow Conditions

The present study investigates thermal performance of a silicon-based multiple micro-jet impingement heat sink for thermal management of electronics. Three-dimensional numerical analysis was performed for steady incompressible laminar flow and conjugate heat transfer through a finite volume solver. A moderate heat flux, 100 W/cm2, is applied at the one end of the silicon substrate, while at the other end jet impingement system is designed. The jet plate is consisted of many jet holes whereas computational domain was simplified by utilizing symmetric boundary conditions across a lateral pitch as well as a central plane in x-direction. The effect of design parameters, namely, jet diameter and jet pitch has been analyzed at constant jet Reynolds numbers under laminar flow conditions on the performance of the heat sink. In view of the low pumping powers available from the micro-pumping devices, low flow rates are applied for the analysis. The cross-flow effects of the spent-flow are investigated for finding out optimum design parameters of the heat sink. The temperature distribution is discussed for number of jets, jet diameter and jet-to-jet spacing across the flow direction. While a moderate thermal resistance of the heat sink was obtained under laminar flow conditions, high performance can be achieved for turbulent flow conditions at the expense of excessive pressure drop which would be investigated in future studies.

A Mechanistic Study of Griseofulvin Dissolution into Surfactant Solutions under Laminar Flow Conditions

1997 ◽  
Vol 86 (10) ◽  
pp. 1132-1137 ◽  
Author(s):  
Venkatramana M. Rao ◽  
Mengfen Lin ◽  
Cynthia K. Larive ◽  
Marylee Z. Southard
Keyword(s):  
Laminar Flow ◽  
Mechanistic Study ◽  
Flow Conditions ◽  
Surfactant Solutions ◽  
Laminar Flow Conditions

scholarly journals Periodicity of Cell Attachment Patterns during Escherichia coli Biofilm Development

2003 ◽  
Vol 185 (18) ◽  
pp. 5632-5638 ◽  
Author(s):  
Konstantin Agladze ◽  
Debra Jackson ◽  
Tony Romeo
Keyword(s):  
Escherichia Coli ◽  
Laminar Flow ◽  
Biofilm Formation ◽  
Cell Attachment ◽  
Bacterial Biofilms ◽  
Flow Conditions ◽  
Biofilm Development ◽  
Complex Architecture ◽  
Activator Inhibitor ◽  
Laminar Flow Conditions

ABSTRACT The complex architecture of bacterial biofilms inevitably raises the question of their design. Microstructure of developing Escherichia coli biofilms was analyzed under static and laminar flow conditions. Cell attachment during early biofilm formation exhibited periodic density patterns that persisted during development. Several models for the origination of biofilm microstructure are considered, including an activator-inhibitor or Turing model.

Abstract 660: Local Hemodynamic Forces and Aqueous Cigarette Smoke Extract Affect Development of Endothelial Dysfunction

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Sindy Giebe ◽  
Coy Brunssen ◽  
Melanie Brux ◽  
Natalia Cockcroft ◽  
Katherine Hewitt ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Dysfunction ◽  
Laminar Flow ◽  
Tobacco Smoking ◽  
Molecular Mechanisms ◽  
Low Flow ◽  
Dependent Manner ◽  
Flow Conditions ◽  
Hemodynamic Forces ◽  
Plaque Phenotype

Endothelial dysfunction is one of the first steps in the development of atherosclerosis. This proinflammatory phenotype is associated with decreased bioavailability of nitric oxide and a corresponding expression profile in the endothelial cells. Tobacco smoking promotes development of atherosclerotic plaques and local hemodynamic forces are key stimuli in this process. Low laminar flow is involved in the development of an unstable plaque phenotype, while high laminar flow has atheroprotective role. The molecular mechanisms controlling plaque stability in response to tobacco smoking remain largely unknown so far. Therefore, we exposed human endothelial cells to cigarette smoke extract (CSEaq) under disturbed flow conditions. Primary human endothelial cells were stimulated with increasing dosages of CSEaq for 24h. Cell viability was reduced by CSEaq in a dose-dependent manner. The impact of specific flow conditions and different doses of CSEaq on the expression of atherosclerosis-related genes was investigated using a cone-and-plate viscometer. High laminar flow induced elongation of endothelial cells in the direction of flow, increased eNOS expression and NO release in a time-dependent manner. This increase was inhibited by CSEaq. Low laminar flow showed no effect on eNOS expression and NO release. The NRF2 antioxidative defense system was also induced by high laminar flow. NRF2 and NRF2 target genes HMOX1 and NQO1 were strongly activated by CSEaq. Furthermore, we monitored the expression of proinflammatory genes. CSEaq strongly induced adhesion molecule ICAM-1. Interestingly, VCAM-1 was unaffected by CSEaq. Induction of endothelial NADPH oxidase isoform 4 by CSEaq was prevented by high laminar flow. Catalase expression was not affected by flow and CSEaq, whereas CSEaq transiently increased SOD1 expression. Endothelial wound healing was improved by atheroprotective high laminar flow. Low flow did not affect wound healing. Furthermore, high laminar flow decreased adhesion of monocytes to endothelial cells, compared to low flow. We suggest novel molecular mechanisms how tobacco smoking promotes the development of endothelial dysfunction. This can contribute to the formation of an unstable atherosclerotic plaque phenotype.

scholarly journals Simulation of micromixing in a T-mixer under laminar flow conditions

2020 ◽  
Vol 222 ◽  
pp. 115706 ◽  
Author(s):  
Cláudio P. Fonte ◽  
David F. Fletcher ◽  
Pierrette Guichardon ◽  
Joelle Aubin
Keyword(s):  
Laminar Flow ◽  
Flow Conditions ◽  
Laminar Flow Conditions

scholarly journals Fabrication and Hypersonic Wind Tunnel Validation of a MEMS Skin Friction Sensor Based on Visual Alignment Technology

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3803
Author(s):  
Xiong Wang ◽  
Nantian Wang ◽  
Xiaobin Xu ◽  
Tao Zhu ◽  
Yang Gao
Keyword(s):  
Wind Tunnel ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Skin Friction ◽  
Flow Conditions ◽  
Friction Coefficients ◽  
Hypersonic Wind Tunnel ◽  
Laminar Flow Conditions ◽  
Turbulent Flow Conditions ◽  
Better Than

MEMS-based skin friction sensors are used to measure and validate skin friction and its distribution, and their advantages of small volume, high reliability, and low cost make them very important for vehicle design. Aiming at addressing the accuracy problem of skin friction measurements induced by existing errors of sensor fabrication and assembly, a novel fabrication technology based on visual alignment is presented. Sensor optimization, precise fabrication of key parts, micro-assembly based on visual alignment, prototype fabrication, static calibration and validation in a hypersonic wind tunnel are implemented. The fabrication and assembly precision of the sensor prototypes achieve the desired effect. The results indicate that the sensor prototypes have the characteristics of fast response, good stability and zero-return; the measurement ranges are 0–100 Pa, the resolution is 0.1 Pa, the repeatability accuracy and linearity are better than 1%, the repeatability accuracy in laminar flow conditions is better than 2% and it is almost 3% in turbulent flow conditions. The deviations between the measured skin friction coefficients and numerical solutions are almost 10% under turbulent flow conditions; whereas the deviations between the measured skin friction coefficients and the analytical values are large (even more than 100%) under laminar flow conditions. The error resources of direct skin friction measurement and their influence rules are systematically analyzed.

Fluorescence observation supporting capillary chromatography based on tube radial distribution of carrier solvents under laminar flow conditions

The Analyst ◽  
2011 ◽  
Vol 136 (5) ◽  
pp. 927-932 ◽  
Author(s):  
Naoya Jinno ◽  
Mari Murakami ◽  
Kiyoshi Mizohata ◽  
Masahiko Hashimoto ◽  
Kazuhiko Tsukagoshi
Keyword(s):  
Laminar Flow ◽  
Radial Distribution ◽  
Capillary Chromatography ◽  
Flow Conditions ◽  
Laminar Flow Conditions ◽  
Fluorescence Observation
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