Documents disponibles écrits par cet auteur

Analysis of bioheat transport through a dual layer biological media / Shadi Mahjoob in Journal of heat transfer, Vol. 132 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031101-1/14] Titre : Analysis of bioheat transport through a dual layer biological media Type de document : texte imprimé Auteurs : Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur Article en page(s) : pp. [031101-1/14] Note générale : Physique Langues : Anglais (eng) Mots-clés : Bioheat  transfer  Biological  tissue/organ  Hyperthermia  Porous  media  Multilayer  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : A comprehensive analysis of bioheat transport through a double layer and multilayer biological media is presented in this work. Analytical solutions have been developed for blood and tissue phase temperatures and overall heat exchange correlations, incorporating thermal conduction in tissue and vascular system, blood-tissue convective heat exchange, metabolic heat generation, and imposed heat flux, utilizing both local thermal nonequilibrium and equilibrium models in porous media theory. Detailed solutions as well as Nusselt number distributions are given, for the first time, for two primary conditions, namely, isolated core region and uniform core temperature. The solutions incorporate the pertinent effective parameters for each layer, such as volume fraction of the vascular space, ratio of the blood, and the tissue matrix thermal conductivities, interfacial blood-tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties. Interface temperature profiles are also obtained based on the continuity of temperature and heat flux through the interface and the physics of the problem. Comparisons between these analytical solutions and limiting cases from previous works display an excellent agreement. These analytical solutions establish a comprehensive presentation of bioheat transport, which can be used to clarify various physical phenomena as well as establishing a detailed benchmark for future works in this area. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Analysis of bioheat transport through a dual layer biological media [texte imprimé] / Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur . - pp. [031101-1/14]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 3 (Mars 2010) . - pp. [031101-1/14] Mots-clés : Bioheat  transfer  Biological  tissue/organ  Hyperthermia  Porous  media  Multilayer  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : A comprehensive analysis of bioheat transport through a double layer and multilayer biological media is presented in this work. Analytical solutions have been developed for blood and tissue phase temperatures and overall heat exchange correlations, incorporating thermal conduction in tissue and vascular system, blood-tissue convective heat exchange, metabolic heat generation, and imposed heat flux, utilizing both local thermal nonequilibrium and equilibrium models in porous media theory. Detailed solutions as well as Nusselt number distributions are given, for the first time, for two primary conditions, namely, isolated core region and uniform core temperature. The solutions incorporate the pertinent effective parameters for each layer, such as volume fraction of the vascular space, ratio of the blood, and the tissue matrix thermal conductivities, interfacial blood-tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties. Interface temperature profiles are also obtained based on the continuity of temperature and heat flux through the interface and the physics of the problem. Comparisons between these analytical solutions and limiting cases from previous works display an excellent agreement. These analytical solutions establish a comprehensive presentation of bioheat transport, which can be used to clarify various physical phenomena as well as establishing a detailed benchmark for future works in this area. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Analysis of heat transfer in consecutive variable cross-sectional domains / Shadi Mahjoob in Journal of heat transfer, Vol. 133 N° 1(N° Spécial) (Janvier 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 1(N° Spécial) (Janvier 2011) . - pp. [011006/1-9] Titre : Analysis of heat transfer in consecutive variable cross-sectional domains : applications in biological media and thermal management Type de document : texte imprimé Auteurs : Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur Année de publication : 2011 Article en page(s) : pp. [011006/1-9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Bioheat  Nonniform  geometry  Electronic  and  biomedical  applications  Variable  area  domain  Porous  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : Temperature prescription and control is important within biological media and in bioheat transport applications such as in hyperthermia cancer treatment in which the unhealthy tissue/organ is subject to an imposed heat flux. Thermal transport investigation and optimization is also important in designing heat management devices and small-scale porous-filled-channels utilized in electronic and biomedical applications. In this work, biological media or the stated heat management devices with a nonuniform geometry are modeled analytically as a combination of convergent, uniform and/or divergent configurations. The biological media is represented as blood saturated porous tissue matrix while incorporating cells and interstices. Two primary models, namely, adiabatic and constant temperature boundary conditions, are employed and the local thermal nonequilibrium and an imposed heat flux are fully accounted for in the presented analytical expressions. Fluid and solid temperature distributions and Nusselt number correlations are derived analytically for variable cross-sectional domain represented by convergent, divergent, and uniform or any combination thereof of these geometries while also incorporating internal heat generation in fluid and/or solid. Our results indicate that the geometrical variations have a substantial impact on the temperature field within the domain and on the surface with an imposed heat flux. It is illustrated that, the temperature distribution within a region of interest can be controlled by a proper design of the multisectional domain as well as proper selection of the porous matrix. These comprehensive analytical solutions are presented for the first time, to the best of the authors' knowledge in literature. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Analysis of heat transfer in consecutive variable cross-sectional domains : applications in biological media and thermal management [texte imprimé] / Shadi Mahjoob, Auteur ; Kambiz Vafai, Auteur . - 2011 . - pp. [011006/1-9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 1(N° Spécial) (Janvier 2011) . - pp. [011006/1-9] Mots-clés : Bioheat  Nonniform  geometry  Electronic  and  biomedical  applications  Variable  area  domain  Porous  media Index. décimale : 536 Chaleur. Thermodynamique Résumé : Temperature prescription and control is important within biological media and in bioheat transport applications such as in hyperthermia cancer treatment in which the unhealthy tissue/organ is subject to an imposed heat flux. Thermal transport investigation and optimization is also important in designing heat management devices and small-scale porous-filled-channels utilized in electronic and biomedical applications. In this work, biological media or the stated heat management devices with a nonuniform geometry are modeled analytically as a combination of convergent, uniform and/or divergent configurations. The biological media is represented as blood saturated porous tissue matrix while incorporating cells and interstices. Two primary models, namely, adiabatic and constant temperature boundary conditions, are employed and the local thermal nonequilibrium and an imposed heat flux are fully accounted for in the presented analytical expressions. Fluid and solid temperature distributions and Nusselt number correlations are derived analytically for variable cross-sectional domain represented by convergent, divergent, and uniform or any combination thereof of these geometries while also incorporating internal heat generation in fluid and/or solid. Our results indicate that the geometrical variations have a substantial impact on the temperature field within the domain and on the surface with an imposed heat flux. It is illustrated that, the temperature distribution within a region of interest can be controlled by a proper design of the multisectional domain as well as proper selection of the porous matrix. These comprehensive analytical solutions are presented for the first time, to the best of the authors' knowledge in literature. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Human eye response to thermal disturbances / Maryam Shafahi in Journal of heat transfer, Vol. 133 N° 1(N° Spécial) (Janvier 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 1(N° Spécial) (Janvier 2011) . - pp. [011009/1-7] Titre : Human eye response to thermal disturbances Type de document : texte imprimé Auteurs : Maryam Shafahi, Auteur ; Kambiz Vafai, Auteur Année de publication : 2011 Article en page(s) : pp. [011009/1-7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Eye  thermal  modeling  Eye  thermal  disturbance  Bioheat  Biological  tissue  Porous  media  Aqueous  humor Index. décimale : 536 Chaleur. Thermodynamique Résumé : Human eye is one of the most sensitive parts of the body when exposed to a thermal heat flux. Since there is no barrier (such as skin) to protect the eye against the absorption of an external thermal wave, the external flux can readily interact with cornea. The modeling of heat transport through the human eye has been the subject of interest for years, but the application of a porous media model in this field is new. In this study, a comprehensive thermal analysis has been performed on the eye. The iris/sclera section of the eye is modeled as a porous medium. The primary sections of the eye, i.e., cornea, anterior chamber, posterior chamber, iris/sclera, lens, and vitreous are considered in our analysis utilizing a two-dimensional finite element simulation. Four different models are utilized to evaluate the eye thermal response to external and internal disturbances. Results are shown in terms of temperature profiles along the pupillary axis. Effects of extreme ambient conditions, blood temperature, blood convection coefficient, ambient temperature, sclera porosity, and perfusion rate on different regions of the eye are investigated. Furthermore, the role of primary thermal transport mechanisms on the eye subject to different conditions is analyzed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Human eye response to thermal disturbances [texte imprimé] / Maryam Shafahi, Auteur ; Kambiz Vafai, Auteur . - 2011 . - pp. [011009/1-7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 1(N° Spécial) (Janvier 2011) . - pp. [011009/1-7] Mots-clés : Eye  thermal  modeling  Eye  thermal  disturbance  Bioheat  Biological  tissue  Porous  media  Aqueous  humor Index. décimale : 536 Chaleur. Thermodynamique Résumé : Human eye is one of the most sensitive parts of the body when exposed to a thermal heat flux. Since there is no barrier (such as skin) to protect the eye against the absorption of an external thermal wave, the external flux can readily interact with cornea. The modeling of heat transport through the human eye has been the subject of interest for years, but the application of a porous media model in this field is new. In this study, a comprehensive thermal analysis has been performed on the eye. The iris/sclera section of the eye is modeled as a porous medium. The primary sections of the eye, i.e., cornea, anterior chamber, posterior chamber, iris/sclera, lens, and vitreous are considered in our analysis utilizing a two-dimensional finite element simulation. Four different models are utilized to evaluate the eye thermal response to external and internal disturbances. Results are shown in terms of temperature profiles along the pupillary axis. Effects of extreme ambient conditions, blood temperature, blood convection coefficient, ambient temperature, sclera porosity, and perfusion rate on different regions of the eye are investigated. Furthermore, the role of primary thermal transport mechanisms on the eye subject to different conditions is analyzed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Restrictions on the validity of the thermal conditions at the porous-fluid interface / Kun Yang in Journal of heat transfer, Vol. 133 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 11 (Novembre 2011) . - pp. [112601/1-12] Titre : Restrictions on the validity of the thermal conditions at the porous-fluid interface : an exact solution Type de document : texte imprimé Auteurs : Kun Yang, Auteur ; Kambiz Vafai, Auteur Année de publication : 2012 Article en page(s) : pp. [112601/1-12] Note générale : Physique Langues : Anglais (eng) Mots-clés : Thermal  condition  Porous-fluis  interface  Local  thermal  nonequilibrium Index. décimale : 536 Chaleur. Thermodynamique Résumé : Thermal conditions at the porous-fluid interface under local thermal nonequilibrium (LTNE) conditions are analyzed in this work. Exact solutions are derived for both the fluid and solid temperature distributions for five of the most fundamental forms of thermal conditions at the interface between a porous medium and a fluid under LTNE conditions and the relationships between these solutions are discussed. This work concentrates on restrictions, based on the physical attributes of the system, which must be placed for validity of the thermal interface conditions. The analytical results clearly point out the range of validity for each model for the first time in the literature. Furthermore, the range of validity of the local thermal equilibrium (LTE) condition is discussed based on the introduction of a critical parameter. The Nusselt number for the fluid at the wall of a channel that contains the fluid and porous medium is also obtained. The effects of the pertinent parameters such as Darcy number, Biot number, Bi, Interface Biot number, Biint, and fluid to solid thermal conductivity ratio are discussed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000133000011 [...] [article] Restrictions on the validity of the thermal conditions at the porous-fluid interface : an exact solution [texte imprimé] / Kun Yang, Auteur ; Kambiz Vafai, Auteur . - 2012 . - pp. [112601/1-12]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 11 (Novembre 2011) . - pp. [112601/1-12] Mots-clés : Thermal  condition  Porous-fluis  interface  Local  thermal  nonequilibrium Index. décimale : 536 Chaleur. Thermodynamique Résumé : Thermal conditions at the porous-fluid interface under local thermal nonequilibrium (LTNE) conditions are analyzed in this work. Exact solutions are derived for both the fluid and solid temperature distributions for five of the most fundamental forms of thermal conditions at the interface between a porous medium and a fluid under LTNE conditions and the relationships between these solutions are discussed. This work concentrates on restrictions, based on the physical attributes of the system, which must be placed for validity of the thermal interface conditions. The analytical results clearly point out the range of validity for each model for the first time in the literature. Furthermore, the range of validity of the local thermal equilibrium (LTE) condition is discussed based on the introduction of a critical parameter. The Nusselt number for the fluid at the wall of a channel that contains the fluid and porous medium is also obtained. The effects of the pertinent parameters such as Darcy number, Biot number, Bi, Interface Biot number, Biint, and fluid to solid thermal conductivity ratio are discussed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO000133000011 [...]

Transient aspects of heat flux bifurcation in porous media / Kun Yang in Journal of heat transfer, Vol. 133 N° 5 (Mai 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 5 (Mai 2011) . - pp. [052602/1-12] Titre : Transient aspects of heat flux bifurcation in porous media : an exact solution Type de document : texte imprimé Auteurs : Kun Yang, Auteur ; Kambiz Vafai, Auteur Année de publication : 2011 Article en page(s) : pp. [052602/1-12] Note générale : Physique Langues : Anglais (eng) Mots-clés : Porous  media  Heat  flux  bifurcation  Transeint  heat  transfer  Local  thermal  nonequilibrium  Analytical  solution Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient thermal response of a packed bed is investigated analytically. A local thermal nonequilibrium model is used to represent the energy transport within the porous medium. The heat flux bifurcation phenomenon in porous media is investigated for temporal conditions and two primary types of heat flux bifurcations in porous media are established. Exact solutions are derived for both the fluid and solid temperature distributions for the constant temperature boundary condition. The fluid, solid, and total Nusselt numbers during transient process are analyzed. A heat exchange ratio is introduced to estimate the influence of interactions between the solid and fluid phases through thermal conduction at the wall within the heat flux bifurcation region. A region where the heat transfer can be described without considering the convection contribution in the fluid phase is found. The two-dimensional thermal behavior for the solid and fluid phases is also analyzed. The temporal temperature differential between the solid and fluid is investigated to determine the domain over which the local thermal equilibrium model is valid. In addition, the characteristic time for reaching steady state conditions is evaluated. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Transient aspects of heat flux bifurcation in porous media : an exact solution [texte imprimé] / Kun Yang, Auteur ; Kambiz Vafai, Auteur . - 2011 . - pp. [052602/1-12]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 5 (Mai 2011) . - pp. [052602/1-12] Mots-clés : Porous  media  Heat  flux  bifurcation  Transeint  heat  transfer  Local  thermal  nonequilibrium  Analytical  solution Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient thermal response of a packed bed is investigated analytically. A local thermal nonequilibrium model is used to represent the energy transport within the porous medium. The heat flux bifurcation phenomenon in porous media is investigated for temporal conditions and two primary types of heat flux bifurcations in porous media are established. Exact solutions are derived for both the fluid and solid temperature distributions for the constant temperature boundary condition. The fluid, solid, and total Nusselt numbers during transient process are analyzed. A heat exchange ratio is introduced to estimate the influence of interactions between the solid and fluid phases through thermal conduction at the wall within the heat flux bifurcation region. A region where the heat transfer can be described without considering the convection contribution in the fluid phase is found. The two-dimensional thermal behavior for the solid and fluid phases is also analyzed. The temporal temperature differential between the solid and fluid is investigated to determine the domain over which the local thermal equilibrium model is valid. In addition, the characteristic time for reaching steady state conditions is evaluated. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]