scholarly journals A Brief Review of Particle Dispersion of Cavity Flow

2020 ◽  
Vol 20 (1) ◽  
pp. 27-41
Author(s):  
Ahmad Sofianuddin A. Sahak ◽  
Nor Azwadi Che Sidik ◽  
Siti Nurul Akmal Yusof
Keyword(s):  
Heat Transfer ◽  
Particle Transport ◽  
Cavity Flow ◽  
Particle Dispersion ◽  
Fluid Particle ◽  
Process Equipment ◽  
Future Research ◽  
Geometrical Parameters ◽  
Engineering Applications ◽  
The Impact

Particles dispersion studies have attracted researchers' interest in understanding the physics behind the phenomena. Fluid-particle transport related to cavity flow is relevant to several natural and engineering applications such as cleaning of process equipment. This paper intends to provide a brief review of researches on the impact parameters, including geometrical parameters of the cavities, flow-related parameters, heat transfer and fluid-particles interaction and identifies opportunities for future research.

scholarly journals Rayleigh–Bénard instability in nanofluids: a comprehensive review

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jyoti Ahuja ◽  
Jyoti Sharma
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Base Fluid ◽  
Random Motion ◽  
Future Research ◽  
Comprehensive Review ◽  
Heat Transfer Efficiency ◽  
Low Volume ◽  
The Impact ◽  
Rayleigh Benard

AbstractThe extraordinary enhancement in heat transfer efficiency of nanofluids at extremely low volume fractions has attracted a lot of attention in identifying the governing mechanisms. The nanoscale effects, Brownian motion (random motion of particles inside the base fluid) and thermophoresis (diffusion of particles due to temperature gradient) are found to be important slip mechanisms in nanofluids. Based on these findings, a set of partial differential equations for conservation laws for nanofluids was formed. Since then, a large number of mathematical studies on convective heat transfer in nanofluids became feasible. The present paper summarizes the studies pertaining to instability of a horizontal nanofluid layer under the impact of various parameters such as rotation, magnetic field, Hall currents and LTNE effects in both porous and non-porous medium. Initially, investigations were made using the model considering fixed initial and boundary conditions on the layer, gradually the model was revised in the light of more practical boundary conditions and recently it has been modified to get new and more interesting results. The exhaustive analysis of instability problems is presented in the paper and prospects for future research are also identified.

scholarly journals A review of acoustic aspect in synthetic jet

2021 ◽  
Vol 351 ◽  
pp. 01003
Author(s):  
Mikołaj Szyca ◽  
Emil Smyk
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Synthetic Jet ◽  
Future Research ◽  
Transfer Enhancement ◽  
Cooling Systems ◽  
Active Cooling ◽  
Jet Actuators ◽  
Transfer Parameters ◽  
The Impact

The synthetic jet actuators are promising heat transfer enhancement devices. They are used in active cooling systems and the future may replace classic fan systems. Although the flow and the heat transfer parameters are very important, these devices must be quiet enough to be used in offices and other spaces. In this paper, the acoustic investigations of the synthetic jet are compiled and discussed. The impact of actuators design on generated noise and the possible ways to noise decreasing are presented. In the end, the list of gaps and challenges are presented for laying down the foundation for future research.

Optimization of the Angle of Attack of Delta-Winglet Vortex Generators Over a Bank of Elliptical-Tubes Heat Exchanger

2013 ◽  
Author(s):  
K. Godazandeh ◽  
M. H. Ansari ◽  
B. Godazandeh ◽  
M. Ashjaee
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Cfd Simulation ◽  
Angle Of Attack ◽  
Vortex Generators ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Transfer Enhancement ◽  
The Impact

In order to reach a more efficient and compact heat exchanger, it is essential to optimize the design, having in mind the impact of different geometrical parameters. Many of the previously cited studies in the area of heat transfer enhancement using vortex generators were confined only to defined points in the possible design space. Thus, a multi-objective optimization study is particularly suitable in order to cover this space entirely. A CFD simulation along with Pareto method were used to simulate the air flow and heat transfer and optimize the design parameters. The angle of attack of a pair of delta-winglets mounted behind each tube is varied between β = −90° and β = +90°. Three elliptical tube rows with inline arrangements are investigated for Reynolds numbers from 500 to 1500 (based on the inlet properties). Use of delta-winglets as heat transfer enhancement elements increases the performance of elliptical-tubes heat exchanger. This enhancement is mainly due to the fact that delta-winglets increase the level of vorticity inside these devices and thus the mixing of the fluid is enhanced.

scholarly journals Biophysical Mechanisms Mediating Fibrin Fiber Lysis

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Nathan E. Hudson
Keyword(s):  
Particle Transport ◽  
Network Architecture ◽  
Transport Phenomena ◽  
Future Research ◽  
Cross Linking ◽  
Mechanical Parameters ◽  
Biophysical Properties ◽  
Blood Clots ◽  
Fibrin Fiber ◽  
The Impact

The formation and dissolution of blood clots is both a biochemical and a biomechanical process. While much of the chemistry has been worked out for both processes, the influence of biophysical properties is less well understood. This review considers the impact of several structural and mechanical parameters on lytic rates of fibrin fibers. The influences of fiber and network architecture, fiber strain, FXIIIa cross-linking, and particle transport phenomena will be assessed. The importance of the mechanical aspects of fibrinolysis is emphasized, and future research avenues are discussed.

Aerothermal Characteristics of Surface-Mounted Round-Edged Slit Ribs with Performance Optimization using Response Surface Methodology

2021 ◽  
pp. 1-46
Author(s):  
Vaibhav Sharma ◽  
Andallib Tariq
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Response Surface Methodology ◽  
Nusselt Number ◽  
Response Surface ◽  
Performance Optimization ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Performance Parameters ◽  
The Impact

Abstract The author has investigated the aerothermal characteristics of round-edged ribs with a continuous slit. The experiments have been performed by mounting an array of ribs on the bottom wall inside a rectangular duct. Heat transfer characteristics have been measured using Liquid crystal Thermography (LCT), whereas flow characteristics have been measured using two-dimensional particle image velocimetry (2D-PIV) technique. Experiments have been performed for flow over a rib having ~20% blockage ratio and 10% open area ratio. Geometrical parameters considered for the study are slit angle (a) and rib pitch to height ratio (p/e). Experiments have been performed for three distinct rib configurations having a values, i.e., 0°, 5° and 10° with different arrangements having p/e values of 5, 10 and 15, at four Reynolds number ranges from 6200-12200. The heat transfer results are evaluated by examining the surface and span wise-averaged distribution of augmented Nusselt Number. Flow field results are explained within the inter rib region by examining the time-averaged normalized velocity fields, streamlines, fluctuation statistics and vorticity distribution. Further, the impact of geometrical design parameters (a and p/e) on different performance parameters, i.e., overall averaged augmented Nusselt Number, Friction Factor Ratio and Thermal Performance Factor have been analyzed at all four Reynolds number using Response Surface Methodology (RSM). Finally, the desired correlations for the performance parameters have been documented, and found in accord with an uncertainty range of ±10%.

An Assessment of Effects of Nanofluids on Heat Transfer Performance of Two-Phase Cooling Systems

2021 ◽  
Author(s):  
Alexander V. Korobko ◽  
Sana Fateh
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Data Centers ◽  
Heat Transfer Performance ◽  
Future Research ◽  
Transfer Performance ◽  
Two Phase ◽  
Cooling Systems ◽  
The Impact ◽  
Two Phase Cooling

Abstract The recent increase in complexity of computations and the expansion of edge computing have led to the emergence of high power density data centers with an urgent demand for more advanced thermal management systems. Two-phase passive cooling systems such as thermosyphons and heat pipes have been widely used in industry to maintain the temperature of the servers below the threshold of failure and carry away a large quantity of heat from a small area. Such systems are economically viable and sustainable since they have no moving parts and consume lower power. However, an upgrade to these cooling systems is imminent due to the ever-increasing power densities of the data centers and more challenging thermal management issues faced by the industry. Nanofluids have emerged recently as a new class of cooling liquids claiming to enhance the heat transfer performance in single and two-phase cooling systems. As per several studies presented in this paper, the thermal performance of thermosyphons is shown to be enhanced by employing nanofluids. In this paper, a comprehensive review is presented on the effect of nanofluids in improving the Critical Heat Flux (CHF) and Heat Transfer Coefficient (HTC) in two-phase cooling systems. The boiling phenomenon and working principles of thermosyphons will be discussed to understand the underlying mechanisms affecting heat transfer in the evaporator region, where the heat is absorbed from the source. The impact of nanoparticle features, concentration, and deposition pattern on HTC enhancement will also be studied. Additionally, estimates of the heat dissipation improvement by using nanofluids along with the bottlenecks and challenges faced in applying such fluids practically are reviewed as well. In conclusion, recommendations are made for future research needed to overcome the risks and commercialize the nanofluids in two-phase cooling systems for providing significant improvement in heat transfer performance as compared to conventional working fluids.

Enhancement of Convective Heat Transfer in Internal Compressible Flows by Stationary Inserts

2010 ◽  
Vol 2 (1) ◽  
Author(s):  
Ramin K. Rahmani ◽  
Emad Y. Tanbour ◽  
Anahita Ayasoufi ◽  
Hosein Molavi
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Compressible Flows ◽  
Incompressible Flows ◽  
Convection Heat Transfer ◽  
Geometrical Parameters ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Numerical Predictions ◽  
The Impact

Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement devices in natural and mixed convection systems with compressible flow. These devices have low maintenance and operating costs, low space requirements, and no moving parts. Through numerical studies, this paper demonstrates how an insert improves heat transfer in buoyancy driven flow. The numerical predictions are validated using experimental data. Using different measurement tools, the global performance of the insert and the impact of the geometrical parameters are studied, leading to identification of the most effective design for a given application.

Self-Compassion and Quality of Life in Adults Who Stutter

2020 ◽  
Vol 29 (4) ◽  
pp. 2097-2108
Author(s):  
Robyn L. Croft ◽  
Courtney T. Byrd
Keyword(s):  
Quality Of Life ◽  
Social Connectedness ◽  
The Self ◽  
Future Research ◽  
Self Compassion ◽  
Adults Who Stutter ◽  
And Gender ◽  
Relationship Of ◽  
The Impact

Purpose The purpose of this study was to identify levels of self-compassion in adults who do and do not stutter and to determine whether self-compassion predicts the impact of stuttering on quality of life in adults who stutter. Method Participants included 140 adults who do and do not stutter matched for age and gender. All participants completed the Self-Compassion Scale. Adults who stutter also completed the Overall Assessment of the Speaker's Experience of Stuttering. Data were analyzed for self-compassion differences between and within adults who do and do not stutter and to predict self-compassion on quality of life in adults who stutter. Results Adults who do and do not stutter exhibited no significant differences in total self-compassion, regardless of participant gender. A simple linear regression of the total self-compassion score and total Overall Assessment of the Speaker's Experience of Stuttering score showed a significant, negative linear relationship of self-compassion predicting the impact of stuttering on quality of life. Conclusions Data suggest that higher levels of self-kindness, mindfulness, and social connectedness (i.e., self-compassion) are related to reduced negative reactions to stuttering, an increased participation in daily communication situations, and an improved overall quality of life. Future research should replicate current findings and identify moderators of the self-compassion–quality of life relationship.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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