The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform

I A Karimi - One of the best experts on this subject based on the ideXlab platform.

  • dispersed plug Flow model for steady State Laminar Flow in a tube with a first order sink at the wall
    Chemical Engineering Science, 2003
    Co-Authors: S Farooq, I A Karimi
    Abstract:

    Abstract Steady State, Laminar Flow transport in a tube with a first order sink at the wall involves two dimensions—radial and axial. In this paper, a novel iterative technique has been proposed for reducing such a two-dimensional model to an equivalent one-dimensional dispersed plug Flow model. The latter yields an analytical expression for the equivalent axial dispersion and a simple, closed form, but approximate, analytical solution of the original two-dimensional problem. The operating range in which this analytical solution is useful has been investigated for a system with mass transfer at the wall.

And R. Arslan - One of the best experts on this subject based on the ideXlab platform.

  • ENTROPY GENERATION ANALYSIS OF FORCED CONVECTION Flow IN A SEMICIRCULAR MICROCHANNEL WITH TiO2/WATER NANOFLUID
    'Begell House', 2019
    Co-Authors: And H. Ekiciler, And R. Arslan
    Abstract:

    In this study, entropy generation caused by heat transfer and friction of forced convection Flow in a semicircular cross-sectioned microchannel with TiO2/water nanofluid was numerically analyzed. The volume concentrations of the nanofluid were taken 1.0\%, 2.0\%, 3.0\%, and 4.0\%. Local and total entropy generation due to the heat transfer and friction were calculated for the microchannel. A three-dimensional analysis was simulated under steady-State Laminar Flow conditions with Reynolds number varying from 100 to 1000. The results of the simulation were obtained using the CFD code. The Flow was considered as hydrodynamically fully developed under thermally developing conditions. A uniform heat flux boundary condition was applied at the bottom surface of the microchannel. According to the results of the numerical study, the effect of the nanofluid volume concentration and fluid velocity on entropy generation was evaluated. The findings show that the total and friction values of entropy generation increase with increasing Flow velocity, while heat transfer entropy generation values decrease since nanofluids improve the heat transfer capability. Also, the results indicate that an increase in the volume concentration of the nanofluid causes friction entropy generation enhancement while heat transfer entropy generation decreases in all cases

  • Entropy generation analysis of forced convection Flow in a semicircular microchannel with TiO2/water nanofluid
    'Begell House', 2019
    Co-Authors: And H. Ekiciler, And R. Arslan
    Abstract:

    In this study, entropy generation caused by heat transfer and friction of forced convection Flow in a semicircular cross-sectioned microchannel with TiO2/water nanofluid was numerically analyzed. The volume concentrations of the nanofluid were taken 1.0%, 2.0%, 3.0%, and 4.0%. Local and total entropy generation due to the heat transfer and friction were calculated for the microchannel. A three-dimensional analysis was simulated under steady-State Laminar Flow conditions with Reynolds number varying from 100 to 1000. The results of the simulation were obtained using the CFD code. The Flow was considered as hydrodynamically fully developed under thermally developing conditions. A uniform heat flux boundary condition was applied at the bottom surface of the microchannel. According to the results of the numerical study, the effect of the nanofluid volume concentration and fluid velocity on entropy generation was evaluated. The findings show that the total and friction values of entropy generation increase with increasing Flow velocity, while heat transfer entropy generation values decrease since nanofluids improve the heat transfer capability. Also, the results indicate that an increase in the volume concentration of the nanofluid causes friction entropy generation enhancement while heat transfer entropy generation decreases in all cases. © 2019 by Begell House, Inc

Kiao Inthavong - One of the best experts on this subject based on the ideXlab platform.

  • pressure distribution and Flow dynamics in a nasal airway using a scale resolving simulation
    Physics of Fluids, 2021
    Co-Authors: James Van Strien, Kendra Shrestha, S Gabriel, Petros Lappas, David Fletcher, Narinder Singh, Kiao Inthavong
    Abstract:

    AirFlow through the nasal cavity exhibits a wide variety of fluid dynamic behaviors due to the intricacy of the nasal geometry. The Flow is naturally unsteady and perhaps turbulent, despite Computational Fluid Dynamics (CFD) in the literature being assumed as having a steady Laminar Flow. Time-dependent simulations can be used to generate detailed data with the potential to uncover new Flow behavior, although they are more computationally intensive than steady-State simulations. Furthermore, verification of CFD results has relied on a reported pressure drop (e.g., nasal resistance) across the nasal airway although the geometries used are different. This study investigated the unsteady nature of inhalation at Flow rates of 10 l/min, 15 l/min, 20 l/min, and 30 l/min. A scale resolving CFD simulation using a hybrid Reynolds-averaged Navier–Stokes--large eddy simulation model was used and compared with experimental measurements of the pressure distribution and the overall pressure drop in the nasal cavity. The experimental results indicated a large pressure drop across the nasal valve and across the nasopharynx, with the latter attributed to a narrow cross-sectional area. At a Flowrate of 30 l/min, the CFD simulations showed that the anterior half of the nasal cavity displayed dominantly Laminar but disturbed Flow behavior in the form of velocity fluctuations. The posterior half of the nasal cavity displayed turbulent activity, characterized by erratic fluctuating velocities, which was enhanced by the wider cross-sectional areas in the coronal plane. At 15 l/min, the Flow field was Laminar dominant with very little disturbance, confirming a steady-State Laminar Flow assumption is viable at this Flow rate.

  • Inhalation of toxic and therapeutic particles in a human nasal cavity
    2nd International Conference on Bioinformatics and Biomedical Engineering iCBBE 2008, 2008
    Co-Authors: Kiao Inthavong, J. Wen, J Y Tu
    Abstract:

    The reconstruction of the nasal cavity from computed tomography (CT) scans to a computational model was performed in order to (i) analyse the air Flow field and (ii) particle dynamics. The scans were converted into MegaWave2 in preparation for processing. The solid modeling program, CATIA combined with the meshing program GAMBIT was then used to establish a model ready for Computational Fluid Dynamics (CFD) analysis. A steady State Laminar Flow at 7.5L/min was used to capture the Flow field. Complex Flow patterns including vortices were found in the nasal valve region. This Flow feature enhances the deposition patterns in the anterior region of the cavity. Fibrous particles and low density particles were introduced into the air Flow stream with their trajectories and deposition location recorded. Low-density drug particles lightens the particle inertial properties however the particle inertia is more sensitive to the particle size rather than the density. The toxicity of fibres has been linked to its length where fibre deposition in the lungs can be carcinogenic. It was found that asbestos had very low deposition, ≈10% and was independent of fibre length, leading to deep lung deposition. In comparison, the carbon fibre was more sensitive to changes in the length and exhibited increases in deposition as the fibre length increased. © Crown Copyright.

S Farooq - One of the best experts on this subject based on the ideXlab platform.

  • dispersed plug Flow model for steady State Laminar Flow in a tube with a first order sink at the wall
    Chemical Engineering Science, 2003
    Co-Authors: S Farooq, I A Karimi
    Abstract:

    Abstract Steady State, Laminar Flow transport in a tube with a first order sink at the wall involves two dimensions—radial and axial. In this paper, a novel iterative technique has been proposed for reducing such a two-dimensional model to an equivalent one-dimensional dispersed plug Flow model. The latter yields an analytical expression for the equivalent axial dispersion and a simple, closed form, but approximate, analytical solution of the original two-dimensional problem. The operating range in which this analytical solution is useful has been investigated for a system with mass transfer at the wall.

Ole Sigmund - One of the best experts on this subject based on the ideXlab platform.

  • topology optimisation for natural convection problems
    International Journal for Numerical Methods in Fluids, 2014
    Co-Authors: Joe Alexandersen, Casper Schousboe Andreasen, Niels Aage, Ole Sigmund
    Abstract:

    This paper demonstrates the application of the density-based topology optimisation approach for the design of heat sinks and micropumps based on natural convection effects. The problems are modelled under the assumptions of steady-State Laminar Flow using the incompressible Navier-Stokes equations coupled to the convection-diffusion equation through the Boussinesq approximation. In order to facilitate topology optimisation, the Brinkman approach is taken to penalise velocities inside the solid domain and the effective thermal conductivity is interpolated in order to accommodate differences in thermal conductivity of the solid and fluid phases. The governing equations are discretised using stabilised finite elements and topology optimisation is performed for two different problems using discrete adjoint sensitivity analysis. The study shows that topology optimisation is a viable approach for designing heat sink geometries cooled by natural convection and micropumps powered by natural convection. Copyright c © 2013 John Wiley & Sons, Ltd.

  • Topology optimisation for natural convection problems
    International Journal for Numerical Methods in Fluids, 2014
    Co-Authors: Joe Alexandersen, Casper Schousboe Andreasen, Niels Aage, Ole Sigmund
    Abstract:

    This paper demonstrates the application of the density-based topology optimisation approach for the design of heat sinks and micropumps based on natural convection effects. The problems are modelled under the assumptions of steady-State Laminar Flow using the incompressible Navier-Stokes equations coupled to the convection-diffusion equation through the Boussinesq approximation. In order to facilitate topology optimisation, the Brinkman approach is taken to penalise velocities inside the solid domain and the effective thermal conductivity is interpolated in order to accommodate differences in thermal conductivity of the solid and fluid phases. The governing equations are discretised using stabilised finite elements and topology optimisation is performed for two different problems using discrete adjoint sensitivity analysis. The study shows that topology optimisation is a viable approach for designing heat sink geometries cooled by natural convection and micropumps powered by natural convection.