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numerical-investigations
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Ethanol spray combustion under a MILD condition: a chemical kinetic study
, Article Energy and Fuels ; Volume 33, Issue 11 , 2019 , Pages 11861-11886 ; 08870624 (ISSN) ; Mardani, A ; Sharif University of Technology
American Chemical Society
2019
Abstract
Moderate or intense low-oxygen dilution (MILD) combustion of liquid fuels has attracted attention because of its advantages in industrial burners and gas turbine applications. Here, numerical investigation has been conducted on an experimental MILD turbulent spray burner. The H∥ flame of Delft spray in a hot co-flow burner is selected, and the Reynolds averaged Navier-Stokes/eddy dissipation concept framework with 40 species/180 reversible reactions through a skeletal chemical mechanism is used in addition to unsteady Lagrangian tracking of spray droplets to investigate the flame structure and chemical kinetic of reacting flow field. At first, current numerical results were compared with...
Numerical investigations of hepatic spheroids metabolic reactions in a perfusion bioreactor
, Article Frontiers in Bioengineering and Biotechnology ; Volume 7 , 2019 ; 22964185 (ISSN) ; Firoozabadi, B ; Firoozbakhsh, K ; Sharif University of Technology
Frontiers Media S.A
2019
Abstract
Miniaturized culture systems of hepatic cells are emerging as a strong tool facilitating studies related to liver diseases and drug discovery. However, the experimental optimization of various parameters involved in the operation of these systems is time-consuming and expensive. Hence, developing numerical tools predicting the function of such systems can significantly reduce the associated cost. In this paper, a perfusion-based three dimensional (3D) bioreactor comprising encapsulated human liver hepatocellular carcinoma (HepG2) spheroids are analyzed. The flow and mass transfer equations for oxygen as well as different metabolites such as albumin, glucose, glutamine, ammonia, and urea were...
Numerical investigation of different geometrical parameters of perforated conical rings on flow structure and heat transfer in heat exchangers
, Article Applied Thermal Engineering ; Volume 156 , 2019 , Pages 494-505 ; 13594311 (ISSN) ; Esfahani, J. A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A numerical study has been performed to investigate the flow and heat transfer characteristics of fluid flow through heat exchanger tubes fitted with perforated conical rings. The holes are circular, and the number of holes N is ranged from 0 to 10. The influences of perforated conical ring diameter ratios D2/D1=0.4,0.5and0.6 and the hole diameter ratios d/D=0.06,0.1and0.14 on average Nusselt number, friction factor and thermal performance factor are reported. This analysis is performed in the turbulent flow regime 4000⩽Re⩽14,000 and the governing equations are solved by using (RNG) k-∊ model. Due to strong turbulent intensity, perforated conical rings lead to more flow perturbation and...
Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers
, Article International Journal of Thermal Sciences ; Volume 138 , 2019 , Pages 75-83 ; 12900729 (ISSN) ; Esfahani, J. A ; Sharif University of Technology
Elsevier Masson SAS
2019
Abstract
A numerical analysis has been performed to investigate the flow structure and thermal hydraulic performance of turbulent flow through circular tube equipped with twisted tapes with different cut shapes. The geometries of cuts are rectangular with different cut ratios 0.25
Numerical investigation of flow pattern and hydrodynamic forces of submerged marine propellers using unsteady boundary element method
, Article Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment ; Volume 233, Issue 1 , 2019 , Pages 67-79 ; 14750902 (ISSN) ; Abbaspoor, M ; Sharif University of Technology
SAGE Publications Ltd
2019
Abstract
In this study, a numerical model of unsteady potential flow around submerged marine propellers has been developed. The boundary element approach in combination with time stepping method to model free wake dynamics has been implemented. An important feature of this method in the simulation of pressure-dominant problems is a proper balance between time and accuracy in the numerical process. Another advantage of time stepping method is that there is no need to define wake geometry before modeling. Due to inherent instability of boundary integral equations, a smoothing function to damp the effect of singularities is imposed to the solution. The main innovative idea of this work is that the...
Prediction of erosive wear locations in centrifugal compressor using CFD simulation and comparison with experimental model
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 2 , 2019 ; 16785878 (ISSN) ; MomeniLarimi, M ; Ganji, B ; Ranjbar, A ; Sharif University of Technology
Springer Verlag
2019
Abstract
Erosive wear is one of the efficiency reduction causes in centrifugal compressors. The presence of suspended solid particles in the fluid causes deformations in different parts of the compressor, especially blades of the impeller. Therefore, erosion not only decreases the part lifetime by destruction of blades form, but also increases energy losses. For this reason, specifying the erosion locations and choosing a suitable material have an important effect on optimum functionality of the machine. In this paper, erosion locations of a compressor impeller by using computational fluid dynamics (CFD) in high temperature and pressure are attained and compared with experimental model. The...
Numerical investigation of injection angle effects on shock vector control performance
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 233, Issue 2 , 2019 , Pages 405-417 ; 09544100 (ISSN) ; Taeibe Rahni, M ; Asadollahi Ghohieh, A ; Banazdeh, A ; Sharif University of Technology
SAGE Publications Ltd
2019
Abstract
The present research paper attempted to utilize a computational investigation for optimizing the fluidic injection angle effects on thrust vectoring. Simulation of a convergent divergent nozzle with shock-vector control method was performed, using URANS approach with Spalart–Allmaras turbulence model. The variable fluidic injection angle is investigated at different aerodynamic and geometric conditions. The current investigation demonstrated that injection angle is an essential parameter in fluidic thrust vectoring. Computational results indicate that optimizing injection angle would improve the thrust vectoring performance. Moreover, dynamic response of starting thrust vectoring would...
Prediction of in-plane elastic properties of graphene in the framework of first strain gradient theory
, Article Meccanica ; Volume 54, Issue 1-2 , 2019 , Pages 299-310 ; 00256455 (ISSN) ; Mehralian, F ; Dehghani Firouz Abadi, R ; Borhan Panah, M. R ; Rahmanian, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is...
Prediction of in-plane elastic properties of graphene in the framework of first strain gradient theory
, Article Meccanica ; Volume 54, Issue 1-2 , 2019 , Pages 299-310 ; 00256455 (ISSN) ; Mehralian, F ; Dehghani Firouz-Abadi, R ; Borhan Panah, M. R ; Rahmanian, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is...
A numerical investigation on natural convection heat transfer in annular-finned concentric horizontal annulus using nanofluids: a parametric study
, Article Heat Transfer Engineering ; 2020 ; Zarei, M. M ; Hakkaki Fard, A ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to 9 (Formula presented.) 105, were studied. The obtained results revealed that Al2O3-water nanofluid has the highest heat transfer rate. The calculated heat transfer rates for Al2O3-water nanofluid for Rayleigh numbers of 9 (Formula presented.) 105, 105, and 104 were respectively up to 12.1%, 26.2%, and 31.6%...
Numerical investigation of second throat exhaust diffuser performance with thrust optimized parabolic nozzles
, Article Aerospace Science and Technology ; Volume 105 , 2020 ; Farahani, M ; Sharif University of Technology
Elsevier Masson SAS
2020
Abstract
Free or restricted shock separation phenomena can occur inside a thrust optimized parabolic (TOP) nozzle during over-expanded operations. In the case of restricted shock separation, a cap shock pattern forms in the nozzle which leads to a substantial total pressure drop. This induces further related issues in the process of ground testing of such nozzles using a second throat exhaust diffuser (STED). In the present study, the flow physics in several TOP nozzles operating at over-expanded conditions is investigated numerically. At first, the strong effect of the initial expansion angle of a TOP nozzle on flow separation pattern and shock structure is demonstrated. Results reveal that for high...
Supersonic separator's dehumidification performance with specific structure: Experimental and numerical investigation
, Article Applied Thermal Engineering ; Volume 179 , October , 2020 ; Farhadi, F ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Supersonic separators are used in gas separation processes such as dehumidification of humid air due to high performance and its good pressure recovery. In the present study, a comprehensive numerical and experimental investigation on the hydrodynamic behavior of air as working fluid and dehumidification performance of supersonic separator have been accomplished. The effect of the operational parameters on shockwave's position are examined. The outcomes show that by increasing the pressure level of supersonic separator, relative error between numerical and experimental results decreases from 20% to less than 10%. The effect of the operational parameters and humidity of inlet air on the...
Numerical investigation on the effect of external varying magnetic field on the mixing of ferrofluid with deionized water inside a microchannel for lab-on-chip systems
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2020 ; Ghassemi, M ; Shafii, M. B ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
Energy-efficient mixing is vital for chemical and fuel processes. To this end, a flow-focusing configuration is proposed to investigate the effect of a uniform magnetic field on the mixing of a water-based ferrofluid with two streams of deionized water. An external and varying magnetic field is imposed on a straight microchannel, and the mixing between the ferrofluid and deionized waters is qualitatively and quantitatively measured. A commercial code based on the finite-element method is used, and the simulations are validated by two experimental studies in the literature. For a magnetic flux density of 10 mT, a signal frequency of 1 Hz, a duty cycle of 0.3, an inlet velocity of 500 µm/s,...
Experimental and numerical investigation of fire effect on GFRP sheets used in strengthening RC structures considering anisotropic properties of composite materials
, Article Proceedings, Annual Conference - Canadian Society for Civil Engineering, 10 June 2008 through 13 June 2008, Quebec City, QC ; Volume 2 , 2008 , Pages 1061-1071 ; 9781605603964 (ISBN) ; Nikopour, H ; Nehdi, M ; Akbaril, J ; Sharif University of Technology
2008
Abstract
In this study a model is presented to predict the residual strength of composite laminates exposed to the heat flux of fire. This model calculates the number of the damaged laminas considering the charred thickness of the composite laminate and then predicts the overall residual strength of the laminate analyzing each lamina. Charred laminas no longer have their initial properties due to decomposition of their polymer matrix. This model can obtain the damaged thickness by introducing a damage temperature, and solving the energy equation for the thermochemical response of the laminate. The thickness of the charred layer is measured for the laminate after exposure to different heat fluxes and...
Experimental & numerical investigation of a centrifugal compressor and numerical study of the area ratio and tip clearance effects on the performance characteristic
, Article 2008 ASME Turbo Expo, Berlin, 9 June 2008 through 13 June 2008 ; Volume 6, Issue PART B , 2008 ; 9780791843161 (ISBN) ; Hajilouy Benisi, A ; Durali, M ; Motavalli, S. M ; Sharif University of Technology
American Society of Mechanical Engineers(ASME)
2008
Abstract
In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was...
Secondary flows, mixing, and chemical reaction analysis of droplet-based flow inside serpentine microchannels with different cross sections
, Article Langmuir ; Volume 37, Issue 17 , 2021 , Pages 5118-5130 ; 07437463 (ISSN) ; Madadelahi, M ; Dizani, M ; Shamloo, A ; Sharif University of Technology
American Chemical Society
2021
Abstract
Chemical bioreactions are an important aspect of many recent microfluidic devices, and their applications in biomedical science have been growing worldwide. Droplet-based microreactors are among the attractive types of unit operations, which utilize droplets for enhancement in both mixing and chemical reactions. In the present study, a finite-volume-method (FVM) numerical investigation is conducted based on the volume-of-fluid (VOF) applying for the droplet-based flows. This multiphase computational modeling is used for the study of the chemical reaction and mixing phenomenon inside a serpentine microchannel and explores the effects of the aspect ratio (i.e., AR = height/width) of...
Numerical investigation of transient thermo-fluid processes in a Ranque-Hilsch vortex tube
, Article International Journal of Refrigeration ; Volume 131 , 2021 , Pages 746-755 ; 01407007 (ISSN) ; Ghorbanian, K ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A 2D numerical investigation is performed to better understand the transient thermo-fluid processes in a vortex tube for a cold mass fraction equal to0.44. The results along the Ranque-Hilsch vortex tube reveal a close agreement with past numerical and experimental data. The distribution of axial, radial, and tangential velocities as well as the stagnation pressure and temperature are examined at different positions for different time steps. The results indicate that the tangential velocity is the most significant velocity component and dominates the heat transfer and energy conversion processes. In addition, it is evident that the core of the cold end experiences the highest pressure...
The numerical investigation of the heat transport in the nanofluids under the impacts of magnetic field: applications in industrial zone
, Article Mathematical Problems in Engineering ; Volume 2021 , 2021 ; 1024123X (ISSN) ; Khan, U ; Ahmed, N ; Mohyud-Din, S. T ; Khan, I ; Fayz-Al-Asad, M ; Sharif University of Technology
Hindawi Limited
2021
Abstract
The dynamics of the nanofluid flow between two plates that are placed parallel to each other is of huge interest due to its numerous applications in different industries. Keeping in view the significance of such flow, investigation of the heat transfer in the Cu-H2O nanofluid is conducted between parallel rotating plates. For more significant results of the study, the squeezing effects are incorporated over the plates that are electrically conducting. The nondimensional flow model is then treated analytically (VPM), and the results are sketched against the preeminent flow parameters. The remarkable heat transfer in the nanofluid is noticed against the Eckert and Prandtl numbers, whereas the...
The numerical investigation of the heat transport in the nanofluids under the impacts of magnetic field: applications in industrial zone
, Article Mathematical Problems in Engineering ; Volume 2021 , 2021 ; 1024123X (ISSN) ; Khan, U ; Ahmed, N ; Mohyud Din, S. T ; Khan, I ; Fayz Al Asad, M ; Sharif University of Technology
Hindawi Limited
2021
Abstract
The dynamics of the nanofluid flow between two plates that are placed parallel to each other is of huge interest due to its numerous applications in different industries. Keeping in view the significance of such flow, investigation of the heat transfer in the Cu-H2O nanofluid is conducted between parallel rotating plates. For more significant results of the study, the squeezing effects are incorporated over the plates that are electrically conducting. The nondimensional flow model is then treated analytically (VPM), and the results are sketched against the preeminent flow parameters. The remarkable heat transfer in the nanofluid is noticed against the Eckert and Prandtl numbers, whereas the...
A numerical investigation on natural convection heat transfer in annular-finned concentric horizontal annulus using nanofluids: a parametric study
, Article Heat Transfer Engineering ; Volume 42, Issue 22 , 2021 , Pages 1926-1948 ; 01457632 (ISSN) ; Zarei, M. M ; Hakkaki Fard, A ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to 9 (Formula presented.) 105, were studied. The obtained results revealed that Al2O3-water nanofluid has the highest heat transfer rate. The calculated heat transfer rates for Al2O3-water nanofluid for Rayleigh numbers of 9 (Formula presented.) 105, 105, and 104 were respectively up to 12.1%, 26.2%, and 31.6%...