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advection-diffusion
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Three-dimensional spread analysis of a Dengue disease model with numerical season control
, Article International Journal of Biomathematics ; Volume 14, Issue 8 , 2021 ; 17935245 (ISSN) ; Hesaaraki, M ; Sharif University of Technology
World Scientific
2021
Abstract
Dengue is among the most important infectious diseases in the world. The main contribution of our paper is to present a mixed system of partial and ordinary differential equations. This combined model is a generalization of the two presented mathematical models (A. L. de Araujo, J. L. Boldrini and B. M. Calsavara, An analysis of a mathematical model describing the geographic spread of dengue disease, J. Math. Anal. Appl. 444 (2016) 298-325) and (L. Cai, X. Li, N. Tuncer, M. Martcheva and A. A. Lashari, Optimal control of a malaria model with asymptomatic class and superinfection, Math. Biosci. 288 (2017) 94-108), describing the geographic spread of dengue disease. Our model has the ability...
Early cancer detection in blood vessels using mobile nanosensors
, Article IEEE Transactions on Nanobioscience ; Volume 18, Issue 2 , 2019 , Pages 103-116 ; 15361241 (ISSN) ; Ahmadzadeh, A ; Wicke, W ; Jamali, V ; Schober, R ; Nasiri Kenari, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we propose using mobile nanosensors (MNSs) for early stage anomaly detection. For concreteness, we focus on the detection of cancer cells located in a particular region of a blood vessel. These cancer cells produce and emit special molecules, so-called biomarkers, which are symptomatic for the presence of anomaly, into the cardiovascular system. Detection of cancer biomarkers with conventional blood tests is difficult in the early stages of a cancer due to the very low concentration of the biomarkers in the samples taken. However, close to the cancer cells, the concentration of the cancer biomarkers is high. Hence, detection is possible if a sensor with the ability to detect...
Multiscale modeling of coupled thermo-hydro-mechanical analysis of heterogeneous porous media
, Article Computer Methods in Applied Mechanics and Engineering ; Volume 391 , 2022 ; 00457825 (ISSN) ; Khoei, A. R ; Sharif University of Technology
Elsevier B.V
2022
Abstract
This paper presents a numerical multiscale formulation for analysis of the transient heat and fluid flow in deformable heterogeneous porous media. Due to the heterogeneity of the media, the direct numerical simulation of the micro-structures leads to high computational costs. Hence, the multi-scale method can provide an efficient computational procedure. To this end, the first-order computational homogenization is adopted for two-scale simulation of THM problems. The governing equations of the problem contain a stress equilibrium equation, a mass continuity equation and an advection–diffusion equation in a fully coupled manner. Accordingly, the proper virtual power relations are defined as a...
Tracer transport in naturally fractured reservoirs: Analytical solutions for a system of parallel fractures
, Article International Journal of Heat and Mass Transfer ; Volume 103 , 2016 , Pages 627-634 ; 00179310 (ISSN) ; Hossieni, M ; Izadmehr, M ; Sharifi, M ; Sharif University of Technology
Elsevier Ltd
Abstract
In naturally fractured reservoirs, modeling of mass transfer between matrix blocks and fractures is an important subject during gas injection or contaminant transport. This study focuses on developing an exact analytical solution to transient tracer transport problem along a discrete fracture in a porous rock matrix. Using Gauss-Legendre quadrature, an expression was obtained in the form of a double integral which is considered as the general transient solution. This solution has the ability to account the following phenomena: advective transport in fractures and molecular diffusion from the fracture to the matrix block. Certain assumptions are made which allow the problem to be formulated...
Experiments and numerical modeling of baffle configuration effects on the performance of sedimentation tanks
, Article Canadian Journal of Civil Engineering ; Volume 40, Issue 2 , 2013 , Pages 140-150 ; 03151468 (ISSN) ; Bakhtyar, R ; Firoozabadi, B ; Barry, D. A ; Sharif University of Technology
2013
Abstract
The hydraulic efficiency of sedimentation basins is reduced by short-circuiting, circulation zones and bottom particleladen jets. Baffles are used to improve the sediment tank performance. In this study, laboratory experiments were used to examine the hydrodynamics of several baffle configurations. An accompanying numerical analysis was performed based on the 2-D Reynolds-averaged Navier-Stokes equations along with the k-ε turbulence closure model. The numerical model was supplemented with the volume-of-fluid technique, and the advection-diffusion equation to simulate the dynamics of particle-laden flow. Model predictions compared well with the experimental data. An empirical function was...
One-dimensional numerical investigation of a cylindrical micro combustor
, Article Proceedings of the ASME Summer Heat Transfer Conference 2009, HT2009 ; Volume 3 , 2009 , Pages 115-123 ; 9780791843581 (ISBN) ; Saediamiri, M ; Saidi, M. S ; Saidi, M. H ; Shafii, M. B ; Sharif University of Technology
Abstract
In this paper, a one-dimensional numerical approach is used to study the effect of various parameters such as micro combustor diameter, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry (9 species and 19 reactions) is used and thermal conductivity of the mixture is considered as a function of species thermal conductivity and temperature by using a set of new relations. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system (A-D-R) that leads to two stiff systems of PDEs, which can not be solved by...
MODSharp: Regional-scale numerical model for quantifying groundwater flux and contaminant discharge into the coastal zone
, Article Environmental Modelling and Software ; Volume 22, Issue 9 , 2007 , Pages 1307-1315 ; 13648152 (ISSN) ; Sharif University of Technology
2007
Abstract
In this paper the development of a quasi-three-dimensional numerical model that can be used for quantifying groundwater inputs and associated contaminant discharged from coastal aquifers into the coastal zone at a regional scale is presented. The present model is called MODSharp. In order to handle problems at a regional scale, the sharp interface approach which is used for conceptualising seawater intrusion, is applied to this model. This model can be used for the simulation of groundwater flow and contaminant transport in layered coastal aquifers at a regional scale. The method of characteristics is used to solve the advection-dispersion equation, which governs contaminant transport in...
Pore-doublet computational fluid dynamic simulation of the effects of dynamic contact angle and interfacial tension alterations on the displacement mechanisms of oil by low salinity water
, Article International Journal of Multiphase Flow ; Volume 143 , 2021 ; 03019322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Using our recently developed model, for the first time in the literature, the effect of fluid/fluid and rock/fluid interactions on the performance of Low Salinity Waterflooding (LSWF, as an Enhanced Oil Recovery process) at pore-doublet scale is investigated. The model is incorporated into OpenFOAM and both the Navier-Stokes equation for oil/water two-phase flow and the advection-diffusion equation for ion transport (at both fluid/fluid and rock/fluid interface) are solved via direct numerical simulation (DNS). The model is validated against imbibition and drainage pore-doublet experiments reported in the literature, and then applied to investigate the sole effect of wettability alteration...
Mechanistic study of the effects of dynamic fluid/fluid and fluid/rock interactions during immiscible displacement of oil in porous media by low salinity water: Direct numerical simulation
, Article Journal of Molecular Liquids ; Volume 322 , 2021 ; 01677322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases...
Pore-doublet computational fluid dynamic simulation of the effects of dynamic contact angle and interfacial tension alterations on the displacement mechanisms of oil by low salinity water
, Article International Journal of Multiphase Flow ; Volume 143 , 2021 ; 03019322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Using our recently developed model, for the first time in the literature, the effect of fluid/fluid and rock/fluid interactions on the performance of Low Salinity Waterflooding (LSWF, as an Enhanced Oil Recovery process) at pore-doublet scale is investigated. The model is incorporated into OpenFOAM and both the Navier-Stokes equation for oil/water two-phase flow and the advection-diffusion equation for ion transport (at both fluid/fluid and rock/fluid interface) are solved via direct numerical simulation (DNS). The model is validated against imbibition and drainage pore-doublet experiments reported in the literature, and then applied to investigate the sole effect of wettability alteration...
Mechanistic study of the effects of dynamic fluid/fluid and fluid/rock interactions during immiscible displacement of oil in porous media by low salinity water: direct numerical simulation
, Article Journal of Molecular Liquids ; Volume 322 , 2021 ; 01677322 (ISSN) ; Fatemi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases...
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
, Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on...
Two-dimensional numerical investigation of a micro combustor
, Article Scientia Iranica ; Volume 17, Issue 6 B , December , 2010 , Pages 433-442 ; 10263098 (ISSN) ; Saidi, M. S ; Saidi, M. H ; Shafii, M. B ; Sharif University of Technology
2010
Abstract
In this paper, a two-dimensional numerical approach is used to study the effect of micro combustor height, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry is used. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system that leads to two stiff systems of PDEs. In the present work, the computational domain is solved through the Strang splitting method, which is suitable for a nonlinear stiff system of PDEs. A revised boundary condition for the velocity equation is applied and its effect on the flow...
Mechanistic study of the effects of dynamic fluid/fluid and fluid/rock interactions during immiscible displacement of oil in porous media by low salinity water: Direct numerical simulation
, Article Journal of Molecular Liquids ; 2020 ; Fatemi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Low salinity waterflooding (LSWF) is a process in which by lowering the ionic strength and/or manipulation of the composition of the injection water, the long term equilibrium in oil/brine/rock system is disturbed to reach a new state of equilibrium through which the oil production will be enhanced due to fluid/fluid and/or rock/fluid interactions. In spite of recent advances in the simulation of the LSWF at core scale and beyond, there are very few works that have modelled and simulated this process at the pore scale specially using direct numerical simulation (DNS). As a result the effects of wettability alteration and/or Interfacial Tension (IFT) change on the distribution of the phases...