Documents disponibles écrits par cet auteur

Dynamics of flow structures and transport phenomena, 1. experimental and numerical techniques for identification and energy content of flow structures / Jyeshtharaj B. Joshi in Industrial & engineering chemistry research, Vol. 48 N° 17 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8244–8284 Titre : Dynamics of flow structures and transport phenomena, 1. experimental and numerical techniques for identification and energy content of flow structures Type de document : texte imprimé Auteurs : Jyeshtharaj B. Joshi, Auteur ; Mandar V. Tabib, Auteur ; Sagar S. Deshpande, Auteur Année de publication : 2009 Article en page(s) : pp. 8244–8284 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Flow  structures  Experimental  fluid  dynamics  techniques  Computational  fluid  dynamics  techniques Résumé : Most chemical engineering equipment is operated in the turbulent regime. The flow patterns in this equipment are complex and are characterized by flow structures of wide range of length and time scales. The accurate quantification of these flow structures is very difficult and, hence, the present design practices are still empirical. Abundant literature is available on understanding of these flow structures, but in very few cases efforts have been made to improve the design procedures with this knowledge. There have been several approaches in the literature to identify and characterize the flow structures qualitatively as well as quantitatively. In the last few decades, several numerical as well as experimental methods have been developed that are complementary to each other with the onset of better computational and experimental facilities. In the present work, the methodologies and applications of various experimental fluid dynamics (EFD) techniques (namely, point measurement techniques such as hot film anemometry, laser Doppler velocimetry, and planar measurement techniques such as particle image velocimetry (PIV), high speed photography, Schlieren shadowgraphy, and the recent volume measurement techniques such as holographic PIV, stereo PIV, etc.), and the computational fluid dynamics (CFD) techniques (such as direct numerical simulation (DNS) and large eddy simulation (LES)) have been discussed. Their chronological developments, relative merits, and demerits have been presented to enable readers to make a judgment as to which experimental/numerical technique to adopt. Also, several notable mathematical quantifiers are reviewed (such as quadrant technique, variable integral time average technique, spectral analysis, proper orthogonal decomposition, discrete and continuous wavelet transform, eddy isolation methodology, hybrid POD−Wavelet technique, etc.). All three of these tools (computational, experimental, and mathematical) have evolved over the past 6−7 decades and have shed light on the physics behind the formation and dynamics of various flow structures. The work ends with addressing the present issues, the existing knowledge gaps, and the path forward in this field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012506 [article] Dynamics of flow structures and transport phenomena, 1. experimental and numerical techniques for identification and energy content of flow structures [texte imprimé] / Jyeshtharaj B. Joshi, Auteur ; Mandar V. Tabib, Auteur ; Sagar S. Deshpande, Auteur . - 2009 . - pp. 8244–8284. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8244–8284 Mots-clés : Flow  structures  Experimental  fluid  dynamics  techniques  Computational  fluid  dynamics  techniques Résumé : Most chemical engineering equipment is operated in the turbulent regime. The flow patterns in this equipment are complex and are characterized by flow structures of wide range of length and time scales. The accurate quantification of these flow structures is very difficult and, hence, the present design practices are still empirical. Abundant literature is available on understanding of these flow structures, but in very few cases efforts have been made to improve the design procedures with this knowledge. There have been several approaches in the literature to identify and characterize the flow structures qualitatively as well as quantitatively. In the last few decades, several numerical as well as experimental methods have been developed that are complementary to each other with the onset of better computational and experimental facilities. In the present work, the methodologies and applications of various experimental fluid dynamics (EFD) techniques (namely, point measurement techniques such as hot film anemometry, laser Doppler velocimetry, and planar measurement techniques such as particle image velocimetry (PIV), high speed photography, Schlieren shadowgraphy, and the recent volume measurement techniques such as holographic PIV, stereo PIV, etc.), and the computational fluid dynamics (CFD) techniques (such as direct numerical simulation (DNS) and large eddy simulation (LES)) have been discussed. Their chronological developments, relative merits, and demerits have been presented to enable readers to make a judgment as to which experimental/numerical technique to adopt. Also, several notable mathematical quantifiers are reviewed (such as quadrant technique, variable integral time average technique, spectral analysis, proper orthogonal decomposition, discrete and continuous wavelet transform, eddy isolation methodology, hybrid POD−Wavelet technique, etc.). All three of these tools (computational, experimental, and mathematical) have evolved over the past 6−7 decades and have shed light on the physics behind the formation and dynamics of various flow structures. The work ends with addressing the present issues, the existing knowledge gaps, and the path forward in this field. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8012506

Dynamics of flow structures and transport phenomena, 2. relationship with design objectives and design optimization / Channamallikarjun S. Mathpati in Industrial & engineering chemistry research, Vol. 48 N° 17 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8285–8311 Titre : Dynamics of flow structures and transport phenomena, 2. relationship with design objectives and design optimization Type de document : texte imprimé Auteurs : Channamallikarjun S. Mathpati, Auteur ; Mandar V. Tabib, Auteur ; Sagar S. Deshpande, Auteur Année de publication : 2009 Article en page(s) : pp. 8285–8311 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Flow  structures  Fluid  dynamics  techniques  Computational  fluid  dynamics  techniques Résumé : There have been several approaches in the literature to identify and characterize flow structures qualitatively as well as quantitatively. In the first part of this review, the methodologies and applications of various experimental fluid dynamics and computational fluid dynamics techniques, as well as mathematical techniques, have been discussed. Their chronological developments, and relative merits and demerits, have been presented to allow readers to make a judgment as to which techniques to adopt. In the present part of the review series, a stepwise procedure is suggested for the design of equipment using flow structure knowledge. An attempt has been made to relate the structure properties (such as age, penetration depth, size, shape, and energy content distribution) to the design parameters (such as mixing time, heat- and mass-transfer coefficient, drag coefficient, dissipation rate, etc.). This understanding of flow structures has brought improvements in the formulations of heuristic models of mass and heat transfer. This review makes an effort in developing insights into the views of earlier established analytic and heuristic theories of heat and mass transfer. The recently revealed dynamics of flow structures (as uncovered through the use of various techniques) has helped in furthering the efforts of developing new theories of heat, mass, and momentum transfer. Such an understanding between the structure dynamics and the transport phenomena has helped in the optimization of flow pattern (for instance, maximization of ratios of heat and mass transfer, as well as mixing, with respect to energy input). In this direction, some success stories have been described that have already been implemented in industry and have good potential for implementation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900396k [article] Dynamics of flow structures and transport phenomena, 2. relationship with design objectives and design optimization [texte imprimé] / Channamallikarjun S. Mathpati, Auteur ; Mandar V. Tabib, Auteur ; Sagar S. Deshpande, Auteur . - 2009 . - pp. 8285–8311. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 17 (Septembre 2009) . - pp. 8285–8311 Mots-clés : Flow  structures  Fluid  dynamics  techniques  Computational  fluid  dynamics  techniques Résumé : There have been several approaches in the literature to identify and characterize flow structures qualitatively as well as quantitatively. In the first part of this review, the methodologies and applications of various experimental fluid dynamics and computational fluid dynamics techniques, as well as mathematical techniques, have been discussed. Their chronological developments, and relative merits and demerits, have been presented to allow readers to make a judgment as to which techniques to adopt. In the present part of the review series, a stepwise procedure is suggested for the design of equipment using flow structure knowledge. An attempt has been made to relate the structure properties (such as age, penetration depth, size, shape, and energy content distribution) to the design parameters (such as mixing time, heat- and mass-transfer coefficient, drag coefficient, dissipation rate, etc.). This understanding of flow structures has brought improvements in the formulations of heuristic models of mass and heat transfer. This review makes an effort in developing insights into the views of earlier established analytic and heuristic theories of heat and mass transfer. The recently revealed dynamics of flow structures (as uncovered through the use of various techniques) has helped in furthering the efforts of developing new theories of heat, mass, and momentum transfer. Such an understanding between the structure dynamics and the transport phenomena has helped in the optimization of flow pattern (for instance, maximization of ratios of heat and mass transfer, as well as mixing, with respect to energy input). In this direction, some success stories have been described that have already been implemented in industry and have good potential for implementation. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900396k

Effect of flow structures on heat transfer in single and multiphase jet reactors / Sagar S. Deshpande in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9428–9440 Titre : Effect of flow structures on heat transfer in single and multiphase jet reactors Type de document : texte imprimé Auteurs : Sagar S. Deshpande, Auteur ; Channamallikarjun S. Mathpati, Auteur ; Sagar S. Gulawani, Auteur Année de publication : 2010 Article en page(s) : pp. 9428–9440 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hot  film  anemometry  Heat  transfer  Multiphase  jet  reactors Résumé : High frequency experimental measurements by hot film anemometry (HFA) of liquid velocities and temperature in the region of vapor−liquid (VL) and solid−liquid (SL) interfaces for two important reactor types, namely, condensation jet and jet loop reactors, have been studied for their heat transfer characteristics. An algorithm for flow structure identification has been devised from velocity data based on (i) zero crossings and (ii) continuous wavelet transform. The wavelet transform algorithm is especially found to be useful in accurately estimating both the age and size distributions of eddies near interfaces in a multiscale framework. Using these distributions, it is shown that the calculated values of heat transfer coefficients (HTC) at the SL and VL interfaces show remarkable correspondence with the HTC values obtained experimentally from instantaneous temperature measurements. For this purpose, a modified capacitance model has been proposed that takes into account the information about both the age and size distributions. The results obtained by the present methodology show the improvement possible for calculating the HTC at interfaces when compared with the earlier surface renewal models. It may therefore be used to study the interaction between flow dynamics and heat transfer behavior in chemical process equipment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900052s [article] Effect of flow structures on heat transfer in single and multiphase jet reactors [texte imprimé] / Sagar S. Deshpande, Auteur ; Channamallikarjun S. Mathpati, Auteur ; Sagar S. Gulawani, Auteur . - 2010 . - pp. 9428–9440. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9428–9440 Mots-clés : Hot  film  anemometry  Heat  transfer  Multiphase  jet  reactors Résumé : High frequency experimental measurements by hot film anemometry (HFA) of liquid velocities and temperature in the region of vapor−liquid (VL) and solid−liquid (SL) interfaces for two important reactor types, namely, condensation jet and jet loop reactors, have been studied for their heat transfer characteristics. An algorithm for flow structure identification has been devised from velocity data based on (i) zero crossings and (ii) continuous wavelet transform. The wavelet transform algorithm is especially found to be useful in accurately estimating both the age and size distributions of eddies near interfaces in a multiscale framework. Using these distributions, it is shown that the calculated values of heat transfer coefficients (HTC) at the SL and VL interfaces show remarkable correspondence with the HTC values obtained experimentally from instantaneous temperature measurements. For this purpose, a modified capacitance model has been proposed that takes into account the information about both the age and size distributions. The results obtained by the present methodology show the improvement possible for calculating the HTC at interfaces when compared with the earlier surface renewal models. It may therefore be used to study the interaction between flow dynamics and heat transfer behavior in chemical process equipment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900052s

Evaluation of local turbulent energy dissipation rate using PIV in jet loop reactor / Sagar S. Deshpande in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 5046–5057 Titre : Evaluation of local turbulent energy dissipation rate using PIV in jet loop reactor Type de document : texte imprimé Auteurs : Sagar S. Deshpande, Auteur ; Mayur J. Sathe, Auteur ; Jyeshtharaj B. Joshi, Auteur Année de publication : 2009 Article en page(s) : pp. 5046–5057 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Jet  loop  reactors  Particle  image  velocimetry  Laser  Doppler  velocimetry  Hot  film  anemometry  Turbulent  dissipation  rate Résumé : In the present work, experimental analysis has been carried out for jet loop reactors to investigate the mean and turbulence parameters. Measurements have been made using particle image velocimetry (PIV), laser Doppler velocimetry (LDV), and hot film anemometry (HFA). The major aim of this work is to evaluate the local value of turbulent dissipation rate (ε) using PIV. LDV has been used as a benchmark for analyzing the mean flow quantities, while HFA has been mainly used for the evaluation of energy spectra. Thus, the relative strength of these instruments was harnessed for better understanding of the flow pattern. A method has been proposed for the evaluation of ε from the experimental data from PIV and HFA based on structure function relationships and 3D energy spectrum. Overall energy balance has been satisfied implicitly to make the method of ε estimation more robust. As an application, the values of ε obtained from the CFD predictions (Large eddy simulations) have been compared with that of the experimental values showing opportunity for improved design of turbulence based on local ε variations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007924 [article] Evaluation of local turbulent energy dissipation rate using PIV in jet loop reactor [texte imprimé] / Sagar S. Deshpande, Auteur ; Mayur J. Sathe, Auteur ; Jyeshtharaj B. Joshi, Auteur . - 2009 . - pp. 5046–5057. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 5046–5057 Mots-clés : Jet  loop  reactors  Particle  image  velocimetry  Laser  Doppler  velocimetry  Hot  film  anemometry  Turbulent  dissipation  rate Résumé : In the present work, experimental analysis has been carried out for jet loop reactors to investigate the mean and turbulence parameters. Measurements have been made using particle image velocimetry (PIV), laser Doppler velocimetry (LDV), and hot film anemometry (HFA). The major aim of this work is to evaluate the local value of turbulent dissipation rate (ε) using PIV. LDV has been used as a benchmark for analyzing the mean flow quantities, while HFA has been mainly used for the evaluation of energy spectra. Thus, the relative strength of these instruments was harnessed for better understanding of the flow pattern. A method has been proposed for the evaluation of ε from the experimental data from PIV and HFA based on structure function relationships and 3D energy spectrum. Overall energy balance has been satisfied implicitly to make the method of ε estimation more robust. As an application, the values of ε obtained from the CFD predictions (Large eddy simulations) have been compared with that of the experimental values showing opportunity for improved design of turbulence based on local ε variations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007924