Documents disponibles écrits par cet auteur

Analytical solution to nonlinear thermal diffusion / Peter Vadasz in Journal of heat transfer, Vol. 132 N° 12 (Décembre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121302-1/6] Titre : Analytical solution to nonlinear thermal diffusion : kirchhoff versus cole–hopf transformations Type de document : texte imprimé Auteurs : Peter Vadasz, Auteur Année de publication : 2010 Article en page(s) : pp. [121302-1/6] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nonlinear  conduction  Kirchhoff  transformation  Cole-hopf  transformation  Nonlinear  thermal  diffusion  Temperature  dependent  properties Index. décimale : 536 Chaleur. Thermodynamique Résumé : The Kirchhoff transformation is the classical method of solution to the nonlinear thermal diffusion problem with temperature dependent properties. It essentially converts the nonlinear problem into a linear one if the thermal diffusivity is approximately constant. Unfortunately, with the only exception of an exponential dependence of the thermal conductivity on temperature, all other thermal conductivity functions produce an inconvenient form for the inverse transform. This paper shows that the Kirchhoff transformation is a particular consequence of the more general Cole–Hopf transformation. However, the classical presentation of the Kirchhoff transformation in terms of a definite integral is more restrictive than the result obtained from the Cole–Hopf transformation and it is this restrictiveness that causes the practical inconvenience in the form of the inverse transform. It is shown that a more compact and practically convenient form of the inverse transform can be obtained by using directly the result from the Cole–Hopf transformation, hence, making its application more attractive. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Analytical solution to nonlinear thermal diffusion : kirchhoff versus cole–hopf transformations [texte imprimé] / Peter Vadasz, Auteur . - 2010 . - pp. [121302-1/6]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 12 (Décembre 2010) . - pp. [121302-1/6] Mots-clés : Nonlinear  conduction  Kirchhoff  transformation  Cole-hopf  transformation  Nonlinear  thermal  diffusion  Temperature  dependent  properties Index. décimale : 536 Chaleur. Thermodynamique Résumé : The Kirchhoff transformation is the classical method of solution to the nonlinear thermal diffusion problem with temperature dependent properties. It essentially converts the nonlinear problem into a linear one if the thermal diffusivity is approximately constant. Unfortunately, with the only exception of an exponential dependence of the thermal conductivity on temperature, all other thermal conductivity functions produce an inconvenient form for the inverse transform. This paper shows that the Kirchhoff transformation is a particular consequence of the more general Cole–Hopf transformation. However, the classical presentation of the Kirchhoff transformation in terms of a definite integral is more restrictive than the result obtained from the Cole–Hopf transformation and it is this restrictiveness that causes the practical inconvenience in the form of the inverse transform. It is shown that a more compact and practically convenient form of the inverse transform can be obtained by using directly the result from the Cole–Hopf transformation, hence, making its application more attractive. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Metabolic mass transfer in monotonic growth of microorganisms / Peter Vadasz 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. [011008/1-9] Titre : Metabolic mass transfer in monotonic growth of microorganisms Type de document : texte imprimé Auteurs : Peter Vadasz, Auteur ; Alisa S. Vadasz, Auteur Année de publication : 2011 Article en page(s) : pp. [011008/1-9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Metabolic  mass  transfer  Monotonic  growth  Microorganisms  Lag Index. décimale : 536 Chaleur. Thermodynamique Résumé : Microorganism growth and reproduction have been traditionally modeled independently of the direct effect of the metabolic process. The latter caused inconsistencies between the modeling results and experimental data. A major inconsistency was linked to the experimentally observed lag phase in the growth process. Attempts to associate the lag phase to delay processes have been recently proven incorrect. The only other alternative is the existence of unstable stationary states resulting from the explicit inclusion of the metabolic mass transfer process via the resource consumption and utilization. The proposed theory that accounts for the latter is presented, analyzed, and compared with experimental data both qualitatively as well as quantitatively. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Metabolic mass transfer in monotonic growth of microorganisms [texte imprimé] / Peter Vadasz, Auteur ; Alisa S. Vadasz, Auteur . - 2011 . - pp. [011008/1-9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 1(N° Spécial) (Janvier 2011) . - pp. [011008/1-9] Mots-clés : Metabolic  mass  transfer  Monotonic  growth  Microorganisms  Lag Index. décimale : 536 Chaleur. Thermodynamique Résumé : Microorganism growth and reproduction have been traditionally modeled independently of the direct effect of the metabolic process. The latter caused inconsistencies between the modeling results and experimental data. A major inconsistency was linked to the experimentally observed lag phase in the growth process. Attempts to associate the lag phase to delay processes have been recently proven incorrect. The only other alternative is the existence of unstable stationary states resulting from the explicit inclusion of the metabolic mass transfer process via the resource consumption and utilization. The proposed theory that accounts for the latter is presented, analyzed, and compared with experimental data both qualitatively as well as quantitatively. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Rendering the transient hot wire experimental method for thermal conductivity estimation to two-phase systems—theoretical leading order results / Peter Vadasz in Journal of heat transfer, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp.[081601-1/7] Titre : Rendering the transient hot wire experimental method for thermal conductivity estimation to two-phase systems—theoretical leading order results Type de document : texte imprimé Auteurs : Peter Vadasz, Auteur Article en page(s) : pp.[081601-1/7] Note générale : Physique Langues : Anglais (eng) Mots-clés : Transient  hot  wire  Porous  media  Nanofluids  Effective  thermal  conductivity  Two-phase  heat  conduction Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient hot wire experimental method for estimating the thermal conductivity of fluids and solids is well established as the most accurate, reliable, and robust technique. It essentially relies on a simple analytical formula derived from the solution of the heat conduction from a line heat source embedded in the target medium. This simple and elegant analytical formulation was derived for uniform and homogeneous fluids or solids. Its extension to two-phase or composite systems, while in practical application, does not have any theoretical basis, and it is by no means obvious that the latter may be applied without corrections to such heterogeneous systems. When it is actually applied as for single-phase systems, it is clearly incorrect. This paper presents preliminary results at the leading order (in the sense of an expansion of the solution in powers of time, applicable to short time scales, consistent with the validity of the transient hot wire method), which render the transient hot wire method to two-phase and composite systems. While these leading order approximations extend the applicability of the same analytical formula to two-phase systems, they also produce additional conditions that need to be fulfilled for such an application to provide reliable experimental results. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Rendering the transient hot wire experimental method for thermal conductivity estimation to two-phase systems—theoretical leading order results [texte imprimé] / Peter Vadasz, Auteur . - pp.[081601-1/7]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp.[081601-1/7] Mots-clés : Transient  hot  wire  Porous  media  Nanofluids  Effective  thermal  conductivity  Two-phase  heat  conduction Index. décimale : 536 Chaleur. Thermodynamique Résumé : The transient hot wire experimental method for estimating the thermal conductivity of fluids and solids is well established as the most accurate, reliable, and robust technique. It essentially relies on a simple analytical formula derived from the solution of the heat conduction from a line heat source embedded in the target medium. This simple and elegant analytical formulation was derived for uniform and homogeneous fluids or solids. Its extension to two-phase or composite systems, while in practical application, does not have any theoretical basis, and it is by no means obvious that the latter may be applied without corrections to such heterogeneous systems. When it is actually applied as for single-phase systems, it is clearly incorrect. This paper presents preliminary results at the leading order (in the sense of an expansion of the solution in powers of time, applicable to short time scales, consistent with the validity of the transient hot wire method), which render the transient hot wire method to two-phase and composite systems. While these leading order approximations extend the applicability of the same analytical formula to two-phase systems, they also produce additional conditions that need to be fulfilled for such an application to provide reliable experimental results. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]