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viscous-dissipation
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Combined Electroosmotically and Pressure Driven Flow of Power-Law Fluids in Rectangular Microchannels
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Hassan (Supervisor) ; Mozafari, Ali Asghar (Supervisor)
Abstract
Electroosmosis is the predominant mechanism for flow generation in lab-on-a-chip devices. These microfluidic devices are microscale laboratories on a microchip that can perform clinical diagnoses. Since most biofluids encountered in these devices are considered to be non-Newtonian and the cross section of microchannels in these devices is close to a rectangular shape, In this study, the hydrodynamically and thermally fully developed combined electroosmotically and pressure driven flow of power-law fluids in rectangular microchannels is analyzed. The governing equations are first made dimensionless and then transformed into new ones based on the computational parameters which provide mesh...
Numerical and Analytical Analysis of Electroosmotic Flow of Non-Newtonian Fluids with Temperature Dependent Properties in the presence of Pressure Gradient in a Slit Micro-Channel
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Hassan (Supervisor)
Abstract
Recent developments in MEMS related areas have increased the demand for practical and novel pumping methods. Utilizing Electroosmotic force for flow generation in microchannels has become really popular recently, because of its reliable operation and control. One of potential applications of MEMS devices is biological and medical analysis which most samples are considered to be non-Newtonian; consequently, thermal transport characteristics of non-Newtonian electroosmotic flow of power-law fluids is investigated in this paper. In this study, thermal and hydrodynamic behavior of non-Newtonian electroosmotic flow of power-law model in a slit microchannel is analyzed. It is assumed that the flow...
Viscous dissipation effects on thermal transport characteristics of combined pressure and electroosmotically driven flow in microchannels
, Article International Journal of Heat and Mass Transfer ; Volume 53, Issue 19-20 , 2010 , Pages 3782-3791 ; 00179310 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Abstract
This study investigates the influence of viscous dissipation on thermal transport characteristics of the fully developed combined pressure and electroosmotically driven flow in parallel plate microchannels subject to uniform wall heat flux. Closed form expressions are obtained for the transverse distributions of electrical potential, velocity and temperature and also for Nusselt number. From the results it is realized that the Brinkman number has a significant effect on Nusselt number. Generally speaking, to increase Brinkman number is to decrease Nusselt number. Although the magnitude of Joule heating can affect Brinkman number dependency of Nusselt number, however the general trend remains...
Viscous dissipation and rarefaction effects on laminar forced convection in microchannels
, Article Journal of Heat Transfer ; Volume 132, Issue 7 , 2010 , Pages 1-12 ; 00221481 (ISSN) ; Saidi, M. H ; Sharif University of Technology
2010
Abstract
Fluid flow in microchannels has some characteristics, which one of them is rarefaction effect related with gas flow. In the present work, hydrodynamically and thermally fully developed laminar forced convection heat transfer of a rarefied gas flow in two microgeometries is studied, namely, microannulus and parallel plate microchannel. The rarefaction effects are taken into consideration using first-order slip velocity and temperature jump boundary conditions. Viscous heating is also included for either the wall heating or the wall cooling case. Closed form expressions are obtained for dimensionless temperature distribution and Nusselt number. The results demonstrate that for both geometries,...
Transient forced convection with viscous dissipation to power-law fluids in thermal entrance region of circular ducts with constant wall heat flux
, Article Energy Conversion and Management ; Volume 50, Issue 4 , 2009 , Pages 1062-1068 ; 01968904 (ISSN) ; Mohammadi, A. A ; Sharif University of Technology
2009
Abstract
A numerical investigation was conducted on the transient behavior of a hydrodynamically, fully developed, laminar flow of power-law fluids in the thermally developing entrance region of circular ducts taking into account the effect of viscous dissipation but neglecting the effect of axial conduction. In this regard, the unsteady state thermal energy equation was solved by using a finite difference method, whereas the steady state thermal energy equation without wall heat flux was solved analytically as the initial condition of the former. The effects of the power-law index and wall heat flux on the local Nusselt number and thermal entrance length were investigated. Moreover, the local...
Transient behavior of fluid flow and heat transfer in vertical channels partially filled with porous medium: Effects of inertial term and viscous dissipation
, Article Energy Conversion and Management ; Volume 61 , September , 2012 , Pages 1-7 ; 01968904 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier
2012
Abstract
In this article, transient hydrodynamic and heat-transfer behavior of Newtonian fluid flow in vertical parallel-plate channels partially filled with a porous medium has been investigated numerically. In this regard, the influences of macroscopic local inertial term and the viscous heating due to the viscous dissipation were taken into account in the momentum equations of porous region and the thermal energy equations, respectively. Moreover, Forchheimer-Brinkman extended Darcy model was used to model fluid flow in the porous region. In addition, an analytical solution was obtained in the case of negligible Brinkman and Forchheimer number values at the steady-state conditions. The predicted...
Transient and steady-state forced convection to power-law fluids in the thermal entrance region of circular ducts: Effects of viscous dissipation, variable viscosity, and axial conduction
, Article Energy Conversion and Management ; Volume 51, Issue 5 , May , 2010 , Pages 1065-1074 ; 01968904 (ISSN) ; Memari, M ; Sharif University of Technology
2010
Abstract
A numerical study was conducted on the transient behavior of a hydrodynamically fully developed, laminar flow of power-law fluids in the thermally developing entrance region of circular ducts with taking into account the effects of viscous dissipation, axial conduction, and variations of viscosity with temperature. In this regard, the unsteady-state thermal energy and momentum equations were solved numerically using a finite-difference method, whereas the steady-state thermal energy equation with constant wall heat flux as the boundary condition was solved analytically as the initial condition of the former. The numerical procedure used in the present work was validated with an analytical...
Thermal transport characteristics pertinent to electrokinetic flow of power-law fluids in rectangular microchannels
, Article International Journal of Thermal Sciences ; Vol. 79, issue , 2014 , p. 76-89 ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
Abstract
In the present study, the thermal characteristics of electroosmotic flow of power-law fluids in rectangular microchannels in the presence of pressure gradient are investigated. The governing equations for fully developed flow under H1 thermal boundary conditions are first made dimensionless and subsequently solved through a finite difference procedure for a non-uniform grid. The influence of the major parameters on thermal features of the flow such as the temperature distribution and Nusselt number is discussed by a complete parametric study. The results reveal that the channel aspect ratio and the non-Newtonian characteristic of the fluid can affect the thermal behavior of the flow. It is...
Thermal transport characteristics of non-newtonian electroosmotic flow in a slit microchannel
, Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011 ; Volume 1 , June , 2011 , Pages 169-176 ; 9780791844632 (ISBN) ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
2011
Abstract
Electroosmosis has many applications in fluid delivery at microscale, sample collection, detection, mixing and separation of various biological and chemical species. In biological applications, most fluids are known to be non-Newtonian. Therefore, the study of thermal features of non-Newtonian electroosmotic flow is of great importance for scientific communities. In the present work, the fully developed electroosmotic flow of power-law fluids in a slit microchannel is investigated. The related equations are transformed into non-dimensional forms and necessary changes are made to adapt them for non-Newtonian fluids of power-law model. Results show that depending on different flow parameters...
Thermally developing electroosmotic flow of power-law fluids in a parallel plate microchannel
, Article International Journal of Thermal Sciences ; Volume 61 , 2012 , Pages 106-117 ; 12900729 (ISSN) ; Saidi, M.H ; Veisi, H ; Fattahi, M ; Sharif University of Technology
2012
Abstract
The present investigation considers the thermally developing electroosmotic flow of power-law fluids through a parallel plate microchannel. Both the viscous dissipation and Joule heating effects are taken into account and a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the resultant eigenvalue problem is solved numerically; nevertheless, an analytical solution is presented for the regions close to the entrance. A parametric study reveals that increasing amounts of the Peclet number result in higher wall...
Second law analysis of slip flow heat transfer in annulus microchannel
, Article Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009, 19 July 2009 through 23 July 2009, San Francisco, CA ; Volume 1 , 2009 , Pages 321-330 ; 9780791843567 (ISBN) ; Asgarshamsi, A ; Saidi, M. H ; Sharif University of Technology
Abstract
In the present work, the second law of thermodynamics analysis has been carried out for steady state hydrodynamically and thermally fully developed laminar gas flow in annulus microchannels with asymmetrically heated walls. The rarefaction effects are taken into consideration using first order slip velocity and temperature jump boundary conditions. Viscous heating is also included for both the hot wall and the cold wall cases. Using the velocity distribution obtained in earlier works, the energy equation is solved to get analytically the temperature distribution and consequently to compute the entropy generation rate. The effects of rarefaction and the annulus geometrical aspect ratio on...
Second law analysis of slip flow forced convection through a parallel plate microchannel
, Article Nanoscale and Microscale Thermophysical Engineering ; Volume 14, Issue 4 , 2010 , Pages 209-228 ; 15567265 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Abstract
In the present work, the second law of thermodynamics analysis has been carried out for steady-state fully developed laminar gas flow in a parallel plate microchannel with asymmetrically heated walls. The rarefaction effects as well as viscous heating effects are taken into consideration. Closed-form expressions are obtained for velocity and temperature distributions and entropy generation rates. The results demonstrate that increasing values of the wall heat fluxes ratio result in greater entropy generation for positive Brinkman numbers, whereas the opposite is true for negative values of Brinkman. However, the effect of the wall heat fluxes ratio on entropy generation becomes insignificant...
Second law analysis for extended graetz problem including viscous dissipation in microtubes
, Article ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2010 Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting, Montreal, QC, 1 August 2010 through 5 August 2010 ; Issue PARTS A AND B , 2010 , Pages 503-514 ; 9780791854501 (ISBN) ; Baghani, M ; Saidi, M. H ; Fluids Engineering Division ; Sharif University of Technology
2010
Abstract
The entropy generation rate has become a useful tool for evaluating the intrinsic irreversibilities associated with a given process or device. This work presents an analytical solution for entropy generation in hydrodynamically fully developed thermally developing laminar flow in a microtube. The rarefaction effects as well as viscous heating effects are taken into consideration, but axial conduction is neglected. Using fully developed velocity profile, the energy equation is solved by means of integral transform. The solution is validated by comparing the local Nusselt numbers against existing literature data. From the results it is realized that the entropy generation decreases as Knudsen...
Physical aspects of rarefied gas flow in micro to nano scale geometries using DSMC
, Article 39th AIAA Fluid Dynamics Conference, 22 June 2009 through 25 June 2009, San Antonio, TX ; 2009 ; 9781563479755 (ISBN) ; Darbandi, M ; Mirjalili, V ; Schneider, G. E ; Sharif University of Technology
Abstract
Rarefied gas flow in micro/nano electro mechanical systems (MEMS/NEMS) does not perform exactly as that in macro-scale devices. The main goal in this study is to investigate mixed subsonic-supersonic flows in micro/nano channels and nozzles and to provide physical descriptions on their behaviors. We use DSMC method as a reliable numerical tool to extend our simulation. It is because the DSMC provides accurate solution for the Boltzmann equations over the entire range of rarefied flow regime or Knudsen numbers. As is known, the appearance of oblique/normal shocks at the inlet of a channel or a nozzle adds to the complexity of internal flow field analyses. We found some very unique physical...
Numerical simulation using a modified solver within OpenFOAM for compressible viscous flows
, Article European Journal of Computational Mechanics ; Volume 28, Issue 6 , 2020 , Pages 541-572 ; Salehi, A. A ; Keshtkar, A ; Shadman, M. M ; Askari, M. H ; Sharif University of Technology
River Publishers
2020
Abstract
In this work, we attempted to develop an Implicit Coupled Density-Based (ICDB) solver using LU-SGS algorithm based on the AUSM+ up scheme in OpenFOAM. Then sonicFoam solver was modified to include viscous dissipation in order to improve its capability to capture shock wave and aerothermal variables. The details of the ICDB solver as well as key implementation details of the viscous dissipation to energy equation were introduced. Finally, two benchmark tests of hypersonic airflow over a flat plate and a 2-D cylinder were simulated to show the accuracy of ICDB solver. To verify and validate the ICDB solver, the obtained results were compared with other published experimental data. It was...
Numerical simulation of viscous dissipation in a micropolar fluid flow through a porous medium
, Article Journal of Applied Mechanics and Technical Physics ; Volume 60, Issue 6 , 2019 , Pages 996-1004 ; 00218944 (ISSN) ; Ashraf, M ; Ali, K ; Sharif University of Technology]
Pleiades Publishing
2019
Abstract
Taking into account the effect of viscous dissipation in the energy equation, we numerically explore the flow of an incompressible micropolar fluid with heat and mass transfer through a resistive porous medium between plane channel walls. By exploiting a similarity transformation, the governing partial differential equations are transformed into a system of nonlinear coupled ordinary differential equations, which are solved numerically for various problem parameters by means of quasi-linearization. It is found that the effect of viscous dissipation is to increase the heat and mass transfer rate at both the lower and upper walls of the channel. © 2019, Pleiades Publishing, Ltd
Modeling and CFD simulation of a mixed-convection flow of regular fluids and nanofluids in vertical porous and regular channels
, Article Heat Transfer - Asian Research ; Vol. 43, issue. 3 , May , 2014 , pp. 243-269 ; ISSN: 1523-1496 ; Dehkordi, A. M ; Sharif University of Technology
Abstract
In this article, the problem of combined forced and free convection in vertical porous and regular channels for both regular fluids and nanofluids has been solved using the CFD technique in the entrance regions of momentum and heat transfer taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models reported in the literature such as the Darcy model, the power of the drag force model, and the clear fluid-compatible model were applied. In the case of nanofluid flow, both the Brownian and thermophoresis molecular transfer mechanisms were considered. The dimensionless distributions of velocity, temperature, and the volume...
Mixed convection in a vertical channel containing porous and viscous fluid regions with viscous dissipation and inertial effects: A perturbation solution
, Article Journal of Heat Transfer ; Volume 133, Issue 9 , 2011 ; 00221481 (ISSN) ; Dehkordi, A. M ; Sharif University of Technology
2011
Abstract
In this paper, combined forced and natural convection in a vertical channel containing both porous and viscous regions taking into account the influences of inertial force and viscous dissipation has been studied. In this regard, fully developed fluid flow in the porous region was modeled using the Brinkman-Forchheimer extended Darcy model. To solve governing equations of both the porous and viscous regions including thermal energy and momentum equations, a two-parameter perturbation method was applied. The velocity and temperature distributions of both the regions were obtained in terms of various parameters such as inertial force, Grashof, Reynolds, and Brinkman numbers, as well as various...
Mixed-convection flow of nanofluids and regular fluids in vertical porous media with viscous heating
, Article Industrial and Engineering Chemistry Research ; Volume 50, Issue 15 , 2011 , Pages 9403-9414 ; 08885885 (ISSN) ; Golmakani, A ; Dehkordi, A. M ; Sharif University of Technology
2011
Abstract
In this article, the problem of combined forced and natural convection in a vertical porous channel for both regular fluids and nanofluids has been solved by perturbation and numerical methods, taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models, including the Darcy model, the power of drag force model, and the clear fluid compatible model, were considered to account for viscous heating. In addition, the mass flux of nanoparticles was also considered in terms of Brownian and thermophoresis mechanisms. The velocity and temperature distributions of both the regular fluid and nanofluid and the Nusselt number...
Impact of swimming gyrotactic microorganisms and viscous dissipation on nanoparticles flow through a permeable medium: a numerical assessment
, Article Journal of Nanomaterials ; Volume 2022 , 2022 ; 16874110 (ISSN) ; Younis, J ; Ali, K ; Rizwan, M ; Ashraf, M ; Abd El Salam, M. A ; Sharif University of Technology
Hindawi Limited
2022
Abstract
In this paper, heat and mass transportation flow of swimming gyrotactic microorganisms (microbes) and solid nanoparticles under the viscous dissipation effect is investigated. The flow model PDEs are renovated with ordinary ones using suitable boundary layer approximations. The system governing the flow model dimensionless equations as well as boundary conditions is numerically treated with the SOR (successive over relaxation) technique. The flow, heat, and mass transport characteristics are examined against the prime parameters. A comparison is examined to be in a good agreement with the earlier results. It is found here that flow and thermal characteristics of the problem are substantially...