Pub Date : 2012-06-01DOI: 10.1260/1759-3093.3.1-2.69
V. Swami, D. Kamble, Dr. B. S. Gawali
In this study, the experimental and numerical investigation of forced convective heat transfer in an optimized rectangular micro-channel heat sink (MCHS) is analyzed using water as the working fluid. The optimization of MCHS has carried out by using CVM (Constant Volume Method) and VVM (Variable Volume Method). From the optimization, it is clear that aspect ratio three which gives the better heat transfer coefficient and lower pressure drop values as comparing with adjacent aspect ratios. A numerical investigation of MCHS based on the finite volume method. The numerical results are validated by comparing the predictions with analytical solutions and experimental data. High heat flux and high coefficient of heat transfer obtained by reducing the core volume of the channel and changing operating conditions. The Optimized micro-channels geometry has a width of 700 μm and a depth of 2100 μm, and is separated by a 350 μm wall. The microchannels are made on cooper plate by using a wire Electro Discharge Machini...
{"title":"Experimental and Numerical Investigation of Forced Convection Heat Transfer in an Optimized Microchannel Heat Sink","authors":"V. Swami, D. Kamble, Dr. B. S. Gawali","doi":"10.1260/1759-3093.3.1-2.69","DOIUrl":"https://doi.org/10.1260/1759-3093.3.1-2.69","url":null,"abstract":"In this study, the experimental and numerical investigation of forced convective heat transfer in an optimized rectangular micro-channel heat sink (MCHS) is analyzed using water as the working fluid. The optimization of MCHS has carried out by using CVM (Constant Volume Method) and VVM (Variable Volume Method). From the optimization, it is clear that aspect ratio three which gives the better heat transfer coefficient and lower pressure drop values as comparing with adjacent aspect ratios. A numerical investigation of MCHS based on the finite volume method. The numerical results are validated by comparing the predictions with analytical solutions and experimental data. High heat flux and high coefficient of heat transfer obtained by reducing the core volume of the channel and changing operating conditions. The Optimized micro-channels geometry has a width of 700 μm and a depth of 2100 μm, and is separated by a 350 μm wall. The microchannels are made on cooper plate by using a wire Electro Discharge Machini...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"3 1","pages":"69-78"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.3.1-2.69","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-06-01DOI: 10.1260/1759-3093.3.1-2.43
M. Reddy, V. V. Rao, S. Sarada, B. Reddy
This paper deals with the determination of thermal conductivity of water based TiO2 nanofluids as a function of temperature in the range of 30°C to 70°C with different volume concentration of TiO2 nanoparticles. In the present experimental investigation, nanofluids are prepared with TiO2 nanoparticles of average size of 21 nm and measurements are made using test setup, specifically designed by namely PA Hilton, UK [17]. Nanofluids with different volume concentrations in the range of 0.2% to 1.0 % (by weight) of TiO2 are used. Based on the experimental results it is found that the thermal conductivity of nanofluids increases with the percentage of volume concentration and temperature. Experimental results are compared with the models available in the open literature. The experimental results of thermal conductivity of nanofluids of the present investigation closely compare with the predictions of the model proposed by Murshed et al [8]. All other models have under-predicted the thermal conductivity of TiO2...
{"title":"Temperature Dependence of Thermal Conductivity of Water Based TiO2 Nanofluids","authors":"M. Reddy, V. V. Rao, S. Sarada, B. Reddy","doi":"10.1260/1759-3093.3.1-2.43","DOIUrl":"https://doi.org/10.1260/1759-3093.3.1-2.43","url":null,"abstract":"This paper deals with the determination of thermal conductivity of water based TiO2 nanofluids as a function of temperature in the range of 30°C to 70°C with different volume concentration of TiO2 nanoparticles. In the present experimental investigation, nanofluids are prepared with TiO2 nanoparticles of average size of 21 nm and measurements are made using test setup, specifically designed by namely PA Hilton, UK [17]. Nanofluids with different volume concentrations in the range of 0.2% to 1.0 % (by weight) of TiO2 are used. Based on the experimental results it is found that the thermal conductivity of nanofluids increases with the percentage of volume concentration and temperature. Experimental results are compared with the models available in the open literature. The experimental results of thermal conductivity of nanofluids of the present investigation closely compare with the predictions of the model proposed by Murshed et al [8]. All other models have under-predicted the thermal conductivity of TiO2...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"3 1","pages":"43-52"},"PeriodicalIF":0.0,"publicationDate":"2012-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.3.1-2.43","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-12-01DOI: 10.1260/1759-3093.2.4.259
R. Dey, Jeevanjyoti Chakraborty, S. Chakraborty
Thermal characteristics of pressure-driven, power-law fluid flows through narrow confinements are analyzed following a semi-analytical approach, by taking into consideration the electrokinetic effects beyond the Debye-Huckel limit. The influence of the induced streaming potential on the flow velocity, temperature and Nusselt number are delineated for parametric variations of the ionic Peclet number and the flow behaviour index. The effect of viscous dissipation is also incorporated into the thermal analysis. The effects of the streaming potential on the hydrodynamic and thermal characteristics are found to be appreciably different for fluids exhibiting different rheological characteristics.
{"title":"Heat Transfer Characteristics of Non-Newtonian Fluid Flows in Narrow Confinements Considering the Effects of Streaming Potential","authors":"R. Dey, Jeevanjyoti Chakraborty, S. Chakraborty","doi":"10.1260/1759-3093.2.4.259","DOIUrl":"https://doi.org/10.1260/1759-3093.2.4.259","url":null,"abstract":"Thermal characteristics of pressure-driven, power-law fluid flows through narrow confinements are analyzed following a semi-analytical approach, by taking into consideration the electrokinetic effects beyond the Debye-Huckel limit. The influence of the induced streaming potential on the flow velocity, temperature and Nusselt number are delineated for parametric variations of the ionic Peclet number and the flow behaviour index. The effect of viscous dissipation is also incorporated into the thermal analysis. The effects of the streaming potential on the hydrodynamic and thermal characteristics are found to be appreciably different for fluids exhibiting different rheological characteristics.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"9 1","pages":"259-268"},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-12-01DOI: 10.1260/1759-3093.2.4.221
I. Mondal, S. Mukhopadhyay, R. Gorla
An analysis of heat and mass transfer for boundary layer forced convective flow of a nanofluid past a moving flat surface parallel to a moving stream is presented. The similarity solutions for the problem are obtained and the reduced ordinary differential equations are solved numerically. To support the validity of the numerical results, comparison is made with known results from the open literature for some particular cases of the present study. When the surface and the fluid move in the opposite directions, dual solutions exist. Numerical results for friction factor, surface heat transfer rate and mass transfer rate have been presented for parametric variations of the Brownian motion parameter Nb, thermophoresis parameter Nt and Lewis number Le. The dependency of the friction factor, surface heat transfer rate (Nusselt number) and mass transfer rate (Sherwood number) on these parameters has been discussed.
{"title":"Dual solutions for the boundary layer flow of a nanofluid over a moving surface","authors":"I. Mondal, S. Mukhopadhyay, R. Gorla","doi":"10.1260/1759-3093.2.4.221","DOIUrl":"https://doi.org/10.1260/1759-3093.2.4.221","url":null,"abstract":"An analysis of heat and mass transfer for boundary layer forced convective flow of a nanofluid past a moving flat surface parallel to a moving stream is presented. The similarity solutions for the problem are obtained and the reduced ordinary differential equations are solved numerically. To support the validity of the numerical results, comparison is made with known results from the open literature for some particular cases of the present study. When the surface and the fluid move in the opposite directions, dual solutions exist. Numerical results for friction factor, surface heat transfer rate and mass transfer rate have been presented for parametric variations of the Brownian motion parameter Nb, thermophoresis parameter Nt and Lewis number Le. The dependency of the friction factor, surface heat transfer rate (Nusselt number) and mass transfer rate (Sherwood number) on these parameters has been discussed.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"221-234"},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-12-01DOI: 10.1260/1759-3093.2.4.235
E. Pankratov, E. Bulaeva
It has been recently shown that manufacturing of an implanted-junction rectifier in a semiconductor heterostructure for optimal relationship between energy of implanted ions, materials and thicknesses of layers of the heterostructure after annealing of radiation defects gives us possibility to increase sharpness of p-n- junction and at the same time to increase homogeneity of dopant distribution in doped area [1,2]. In this paper we consider a possibility to decrease quantity of radiation defects, which were generated during ion implantation, using porous epitaxial layers of the heterostructure.
{"title":"Using porous layers to decrease quantity of radiation defects, generated during ion implantation","authors":"E. Pankratov, E. Bulaeva","doi":"10.1260/1759-3093.2.4.235","DOIUrl":"https://doi.org/10.1260/1759-3093.2.4.235","url":null,"abstract":"It has been recently shown that manufacturing of an implanted-junction rectifier in a semiconductor heterostructure for optimal relationship between energy of implanted ions, materials and thicknesses of layers of the heterostructure after annealing of radiation defects gives us possibility to increase sharpness of p-n- junction and at the same time to increase homogeneity of dopant distribution in doped area [1,2]. In this paper we consider a possibility to decrease quantity of radiation defects, which were generated during ion implantation, using porous epitaxial layers of the heterostructure.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"235-258"},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-12-01DOI: 10.1260/1759-3093.2.4.199
S. Pramanik, A. Mukhopadhyay, S. Sen
Thermally and hydrodynamically fully developed combined pressure-driven and electroosmotic flow through a channel with three immiscible fluids has been simulated for isoflux wall boundary conditions. Closed form expressions have been developed for velocity and temperature profiles and Nusselt number. The results indicate strong effects of fluid layer thickness, force fields and boundary conditions.
{"title":"Fully Developed Hydrodynamic and Thermal Transport of Combined Pressure and Electrokinetically-driven Flow in a Microchannel With Three Immiscible Fluids","authors":"S. Pramanik, A. Mukhopadhyay, S. Sen","doi":"10.1260/1759-3093.2.4.199","DOIUrl":"https://doi.org/10.1260/1759-3093.2.4.199","url":null,"abstract":"Thermally and hydrodynamically fully developed combined pressure-driven and electroosmotic flow through a channel with three immiscible fluids has been simulated for isoflux wall boundary conditions. Closed form expressions have been developed for velocity and temperature profiles and Nusselt number. The results indicate strong effects of fluid layer thickness, force fields and boundary conditions.","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"199-220"},"PeriodicalIF":0.0,"publicationDate":"2011-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.117
E. Pankratov
{"title":"Using Native Inhomogeneity of Heterostructure to Decrease Dimensions of Planar Field-Effect Transistors","authors":"E. Pankratov","doi":"10.1260/1759-3093.2.2-3.117","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.117","url":null,"abstract":"","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"117-128"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.187
K. Tanuja, A. Sarkar, Sarit K. Das
FEM model of the double helical structure of the DNA together with the interconnecting hydrogen bonds is developed in this work. The results of the FEM model is compared with the simplistic equivalent rod model. Simulations for deformations under axial, torsional, radial and bending loading are performed. The action of enzymes on DNA can be assumed to be in the form of combination of these loadings. Normalized results of axial, torsional, radial and bending stiffness are computed. The effect of hydrogen bond stiffness on these quantities is analysed. From the results obtained it is inferred that though the hydrogen bond stiffness value has no effect on the axial and torsional stiffness, the radial and the bending stiffness are affected by the hydrogen bonds. Beyond a critical value of the bond stiffness it is observed that the bending and radial stiffness undergo a rapid change and stabilize to a higher value. The results obtained from the present work thus identify the parameter regimes of applicability ...
{"title":"A Computational Model to Determine the Effect of Interconnecting Hydrogen Bonds in DNA Deformation","authors":"K. Tanuja, A. Sarkar, Sarit K. Das","doi":"10.1260/1759-3093.2.2-3.187","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.187","url":null,"abstract":"FEM model of the double helical structure of the DNA together with the interconnecting hydrogen bonds is developed in this work. The results of the FEM model is compared with the simplistic equivalent rod model. Simulations for deformations under axial, torsional, radial and bending loading are performed. The action of enzymes on DNA can be assumed to be in the form of combination of these loadings. Normalized results of axial, torsional, radial and bending stiffness are computed. The effect of hydrogen bond stiffness on these quantities is analysed. From the results obtained it is inferred that though the hydrogen bond stiffness value has no effect on the axial and torsional stiffness, the radial and the bending stiffness are affected by the hydrogen bonds. Beyond a critical value of the bond stiffness it is observed that the bending and radial stiffness undergo a rapid change and stabilize to a higher value. The results obtained from the present work thus identify the parameter regimes of applicability ...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"187-198"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.129
C. Saleel, A. Shaija, S. Jayaraj
Several fluid movement techniques in microchannel have been discussed in the past, the most recent technique is by applying an electric field to a fluid enclosed in a microchannel (viz electroosmotic flow). An immersed boundary method (IBM) is a methodology to deal with a body in the computational domain having complex or simple boundary which does not necessarily have to conform a Cartesian grid. The present study is an IBM based numerical investigation of two-dimensional transient electroosmotic flows in a microchannel populated with rectangular blocks to constrict the flow which eventually aims a short mixing channel. Electroosmotic potential, leads to the formation of Electrical Double Layer (EDL), is governed by Poisson-Boltzmann equation and is solved by PSOR method. The hyperbolic non-linearity associated with this equation is suitably tackled by the Taylor series expansion (neglecting the higher order terms). The electroosmotic flow is governed by the continuity equation impregnated with a mass so...
{"title":"Computational Simulation of Electroosmotic Flow Using Immersed Boundary Method","authors":"C. Saleel, A. Shaija, S. Jayaraj","doi":"10.1260/1759-3093.2.2-3.129","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.129","url":null,"abstract":"Several fluid movement techniques in microchannel have been discussed in the past, the most recent technique is by applying an electric field to a fluid enclosed in a microchannel (viz electroosmotic flow). An immersed boundary method (IBM) is a methodology to deal with a body in the computational domain having complex or simple boundary which does not necessarily have to conform a Cartesian grid. The present study is an IBM based numerical investigation of two-dimensional transient electroosmotic flows in a microchannel populated with rectangular blocks to constrict the flow which eventually aims a short mixing channel. Electroosmotic potential, leads to the formation of Electrical Double Layer (EDL), is governed by Poisson-Boltzmann equation and is solved by PSOR method. The hyperbolic non-linearity associated with this equation is suitably tackled by the Taylor series expansion (neglecting the higher order terms). The electroosmotic flow is governed by the continuity equation impregnated with a mass so...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"129-150"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-06-01DOI: 10.1260/1759-3093.2.2-3.109
Abhimanyu Gavasane, S. Sachdev, Bharat K. Mittal, U. Bhandarkar, A. Agrawal
The Maxwell slip boundary condition is widely used to compute the slip velocity at the wall under rarefied flow condition. In this paper, we apply the Direct Simulation Monte Carlo (DSMC) method on a Couette flow problem in order to evaluate this boundary condition. The computations are performed at different values of tangential momentum accommodation coefficient (between 0.1 and 1) and Knudsen numbers (Kn between 0.001 and 3), at 500 K for Argon, with the aim of comparing the ensuing slip length to that predicted by Maxwell's formula. It is found that the boundary condition is accurate up to a Kn = 0.1 but not at higher Knudsen numbers. Although it has been known that the slip boundary condition is valid only for small Knudsen numbers, the critical Knudsen number from where the deviation begins is not well documented. The present results indicate that such deviations occur at Kn = 0.1 in flows that are bounded by opposing walls. At higher Knudsen numbers, the Knudsen layers overlap and the collisions of...
{"title":"A Critical Assessment of the Maxwell Slip Boundary Condition for Rarified Wall Bounded Flows","authors":"Abhimanyu Gavasane, S. Sachdev, Bharat K. Mittal, U. Bhandarkar, A. Agrawal","doi":"10.1260/1759-3093.2.2-3.109","DOIUrl":"https://doi.org/10.1260/1759-3093.2.2-3.109","url":null,"abstract":"The Maxwell slip boundary condition is widely used to compute the slip velocity at the wall under rarefied flow condition. In this paper, we apply the Direct Simulation Monte Carlo (DSMC) method on a Couette flow problem in order to evaluate this boundary condition. The computations are performed at different values of tangential momentum accommodation coefficient (between 0.1 and 1) and Knudsen numbers (Kn between 0.001 and 3), at 500 K for Argon, with the aim of comparing the ensuing slip length to that predicted by Maxwell's formula. It is found that the boundary condition is accurate up to a Kn = 0.1 but not at higher Knudsen numbers. Although it has been known that the slip boundary condition is valid only for small Knudsen numbers, the critical Knudsen number from where the deviation begins is not well documented. The present results indicate that such deviations occur at Kn = 0.1 in flows that are bounded by opposing walls. At higher Knudsen numbers, the Knudsen layers overlap and the collisions of...","PeriodicalId":89942,"journal":{"name":"International journal of micro-nano scale transport","volume":"2 1","pages":"109-116"},"PeriodicalIF":0.0,"publicationDate":"2011-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1260/1759-3093.2.2-3.109","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66151748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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