A. Dukler - Academia.edu (original) (raw)
Papers by A. Dukler
Transitions for vertical upflow of gas-liquid systems are modeled. A method for predicting transi... more Transitions for vertical upflow of gas-liquid systems are modeled. A method for predicting transitions is soundly based on the results of the work. With the initial conceptual studies of the transient flow regime behavior complete in this report, it will be possible to write computer programs to explore the ideas in the second report of the study.
International Journal of Multiphase Flow, 1987
ABSTRACT This paper analyzes the hydrodynamics near the discharge of a pipe carrying gas and liqu... more ABSTRACT This paper analyzes the hydrodynamics near the discharge of a pipe carrying gas and liquid in horizontal stratified flow. It is shown that for high-viscosity liquids, pipe length may have a considerable effect on the transition from the stratified to nonstratified (annular or intermittent) flow pattern. This leads to a flow-pattern map which contains the pipe length as a parameter for this transition boundary.
Industrial & Engineering Chemistry Fundamentals, 1970
International Journal of Multiphase Flow, 1976
International Journal of Multiphase Flow, 1977
International Journal of Multiphase Flow, 1993
Glycobiology, 2003
In this study, we use a novel glycan array to analyze the glycan-binding antibody repertoire in a... more In this study, we use a novel glycan array to analyze the glycan-binding antibody repertoire in a pool of affinitypurified IgG collected from a healthy human population. The glycan array used is based on mono-and oligosaccharides covalently linked to the surface via a long linker at their reducing ends. They are thus presented to the medium with a well-defined orientation and are accessible for specific binding by glycan-binding proteins, such as antibodies and lectins. A novel anticellulose antibody was detected that binds specifically to b4-linked saccharides with a preference for glucopyranose over galactopyranose residues. We also found previously known antiglycan antibodies against mono-and oligosaccharides that are constituents of commonly occurring bacterial polysaccharides. We propose that this array can facilitate high-throughput screening of glycan-binding proteins and the search for biomarkers for personalized medicine.
Experiments in Fluids, 1989
... 9 Springer-Verlag 1989 An experimental study of gas-liquid slug flow Zai-Sha Mao and AE Dukle... more ... 9 Springer-Verlag 1989 An experimental study of gas-liquid slug flow Zai-Sha Mao and AE Dukler University of Houston, Dept. of Chemical Engineering, Houston, TX 77204-4792, USA Abstract. ... l~ lrB n u v~, v~ UNLS UNrB voT v~ 12 w (y) X Y O~ ~LS Q ff Too () ...
Chemical Engineering Science, 1991
The numerical method presented in Part I is used to simulate the liquid flow around a single Tayl... more The numerical method presented in Part I is used to simulate the liquid flow around a single Taylor bubble in a vertical tube. A modified low Reynolds number k--E model is incorporated in the simulation for accurate prediction of the wall shear stress when liquid flow is turbulent. A model for free surface damping of turbulence is also included in the numerical process. The predicted rise velocily and the shape of the bubble as well as the film thickness and the wall shear stress are in good agreement with new experiments as well as earlier data.
AIChE Journal, 1991
The structure of thin, wavy falling films was studied to evaluate whether the random-appearing wa... more The structure of thin, wavy falling films was studied to evaluate whether the random-appearing wave structure is a result of deterministic chaos or a purely stochastic process. The time-varying film thickness was obtained at different spatial locations near the point of wave inception for flow rates in the range of Under all conditions the wave structure was aperiodic in nature and displayed none of the known transitions to chaos. However, the power spectra followed an exponential decay law at high frequencies that is characteristic of chaotic systems. The estimated attractor dimension, used to characterize the complexity of a chaotic system, was much higher than those of known model chaotic systems. It is demonstrated that these high values could be explained due to small levels of noise present in experimental situations. Since experimental data are seldom noise free, a basic limitation in applying these methods to experimental measurements is demonstrated.
AIChE Journal, 1989
Three isolated waves of differing amplitude and shape were selected from experimental measurement... more Three isolated waves of differing amplitude and shape were selected from experimental measurements of a falling liquid film at Re = 880 for study using an algorithm developed for solution of the Navier-Stokes equations. The method computes the velocity and pressure fields as well as the velocity of the wave. The results show that large streamwise accelerations exist along with regions of recirculating flow in a moving coordinate system. These features can explain the enhanced rates of heat and mass transfer observed in wavy film flow. Computed wave velocities and wall shear stress were in reasonably good agreement with measurements. Wave velocity is shown to be sensitive to small variations in the wave shape and explains the apparent random variation of wave velocity with amplitude that has been observed experimentally. This numerical experiment points to the shortcomings of the many methods used to model large waves on falling films that have been based on parabolic velocity profiles.
AIChE Journal, 1986
Upward cocurrent gas-liquid annular flow was investigated in a 50.8 mm ID cylindrical vertical pi... more Upward cocurrent gas-liquid annular flow was investigated in a 50.8 mm ID cylindrical vertical pipe. The film flow was studied by measuring instantaneous local film thickness, wall shear stress, and pressure gradient. Analysis of these data revealed that at low gas flow rates the film motion is controlled by a switching mechanism, as speculated by Moalem-Maron and Dukler (1984). In the region of high gas flow rates the switching process is suppressed and traveling roll waves characterize the film motion. the mixing processes associated with heat or mass transfer must be based on the dynamics of switching rather than on wave motion. At high gas flow rates the interface is characteristic of a sequence of traveling roll waves as described by others. The switching is suppressed.
AIChE Journal, 1990
Numerical simulations of mass transfer into falling liquid films, both through the wavy interface... more Numerical simulations of mass transfer into falling liquid films, both through the wavy interface and from the wall, have been performed for experimentally measured large waves within which the flow fields have been computed. Experiments have shown that the occurrence of waves on free falling films causes dramatic increases in mass transfer into the film, even under laminar flow conditions. Wave effects have been modeled in several ways, none of which predicts the observed rate of enhancement. The present numerical procedure includes solving the convective-diffusion equation for wavy films by extending a technique developed for hydrodynamic simulation. The presence of waves is shown to cause significant velocities normal to each interface. In conjunction with recirculation within the large waves, these flow patterns produce transfer rates for large waves that are several times larger than predicted for quasiparallel velocity fields. Experimental wave structure data were used to define the dimensions and frequency of an average large wave and surrounding substrate. Computed transfer rates at both the gas-liquid interface and the wall for a film composed of a periodic sequence of average waves agree well with published data. These simulations confirm the inadequacy of parabolic, or Kapitza-type velocity profiles in formulating transport models.
AIChE Journal, 1988
The structure of the wavy interface on a falling liquid film is studied for conditions of counter... more The structure of the wavy interface on a falling liquid film is studied for conditions of countercurrent gas flow in order to investigate mechanisms for flooding. Measurements taken just below the liquid feed and at 1.7 m down the tube show that under all conditions, including flooding, the waves propagate only downward and are never of such amplitude as to bridge the tube. These observations are in contrast to speculations in the literature that upward flow of waves or bridging of liquid due to waves cause flooding. In the mechanism suggested, flooding is due to flow reversal in the film just at the liquid entry.
International Journal of Multiphase Flow, 1980
Transitions for vertical upflow of gas-liquid systems are modeled. A method for predicting transi... more Transitions for vertical upflow of gas-liquid systems are modeled. A method for predicting transitions is soundly based on the results of the work. With the initial conceptual studies of the transient flow regime behavior complete in this report, it will be possible to write computer programs to explore the ideas in the second report of the study.
International Journal of Multiphase Flow, 1987
ABSTRACT This paper analyzes the hydrodynamics near the discharge of a pipe carrying gas and liqu... more ABSTRACT This paper analyzes the hydrodynamics near the discharge of a pipe carrying gas and liquid in horizontal stratified flow. It is shown that for high-viscosity liquids, pipe length may have a considerable effect on the transition from the stratified to nonstratified (annular or intermittent) flow pattern. This leads to a flow-pattern map which contains the pipe length as a parameter for this transition boundary.
Industrial & Engineering Chemistry Fundamentals, 1970
International Journal of Multiphase Flow, 1976
International Journal of Multiphase Flow, 1977
International Journal of Multiphase Flow, 1993
Glycobiology, 2003
In this study, we use a novel glycan array to analyze the glycan-binding antibody repertoire in a... more In this study, we use a novel glycan array to analyze the glycan-binding antibody repertoire in a pool of affinitypurified IgG collected from a healthy human population. The glycan array used is based on mono-and oligosaccharides covalently linked to the surface via a long linker at their reducing ends. They are thus presented to the medium with a well-defined orientation and are accessible for specific binding by glycan-binding proteins, such as antibodies and lectins. A novel anticellulose antibody was detected that binds specifically to b4-linked saccharides with a preference for glucopyranose over galactopyranose residues. We also found previously known antiglycan antibodies against mono-and oligosaccharides that are constituents of commonly occurring bacterial polysaccharides. We propose that this array can facilitate high-throughput screening of glycan-binding proteins and the search for biomarkers for personalized medicine.
Experiments in Fluids, 1989
... 9 Springer-Verlag 1989 An experimental study of gas-liquid slug flow Zai-Sha Mao and AE Dukle... more ... 9 Springer-Verlag 1989 An experimental study of gas-liquid slug flow Zai-Sha Mao and AE Dukler University of Houston, Dept. of Chemical Engineering, Houston, TX 77204-4792, USA Abstract. ... l~ lrB n u v~, v~ UNLS UNrB voT v~ 12 w (y) X Y O~ ~LS Q ff Too () ...
Chemical Engineering Science, 1991
The numerical method presented in Part I is used to simulate the liquid flow around a single Tayl... more The numerical method presented in Part I is used to simulate the liquid flow around a single Taylor bubble in a vertical tube. A modified low Reynolds number k--E model is incorporated in the simulation for accurate prediction of the wall shear stress when liquid flow is turbulent. A model for free surface damping of turbulence is also included in the numerical process. The predicted rise velocily and the shape of the bubble as well as the film thickness and the wall shear stress are in good agreement with new experiments as well as earlier data.
AIChE Journal, 1991
The structure of thin, wavy falling films was studied to evaluate whether the random-appearing wa... more The structure of thin, wavy falling films was studied to evaluate whether the random-appearing wave structure is a result of deterministic chaos or a purely stochastic process. The time-varying film thickness was obtained at different spatial locations near the point of wave inception for flow rates in the range of Under all conditions the wave structure was aperiodic in nature and displayed none of the known transitions to chaos. However, the power spectra followed an exponential decay law at high frequencies that is characteristic of chaotic systems. The estimated attractor dimension, used to characterize the complexity of a chaotic system, was much higher than those of known model chaotic systems. It is demonstrated that these high values could be explained due to small levels of noise present in experimental situations. Since experimental data are seldom noise free, a basic limitation in applying these methods to experimental measurements is demonstrated.
AIChE Journal, 1989
Three isolated waves of differing amplitude and shape were selected from experimental measurement... more Three isolated waves of differing amplitude and shape were selected from experimental measurements of a falling liquid film at Re = 880 for study using an algorithm developed for solution of the Navier-Stokes equations. The method computes the velocity and pressure fields as well as the velocity of the wave. The results show that large streamwise accelerations exist along with regions of recirculating flow in a moving coordinate system. These features can explain the enhanced rates of heat and mass transfer observed in wavy film flow. Computed wave velocities and wall shear stress were in reasonably good agreement with measurements. Wave velocity is shown to be sensitive to small variations in the wave shape and explains the apparent random variation of wave velocity with amplitude that has been observed experimentally. This numerical experiment points to the shortcomings of the many methods used to model large waves on falling films that have been based on parabolic velocity profiles.
AIChE Journal, 1986
Upward cocurrent gas-liquid annular flow was investigated in a 50.8 mm ID cylindrical vertical pi... more Upward cocurrent gas-liquid annular flow was investigated in a 50.8 mm ID cylindrical vertical pipe. The film flow was studied by measuring instantaneous local film thickness, wall shear stress, and pressure gradient. Analysis of these data revealed that at low gas flow rates the film motion is controlled by a switching mechanism, as speculated by Moalem-Maron and Dukler (1984). In the region of high gas flow rates the switching process is suppressed and traveling roll waves characterize the film motion. the mixing processes associated with heat or mass transfer must be based on the dynamics of switching rather than on wave motion. At high gas flow rates the interface is characteristic of a sequence of traveling roll waves as described by others. The switching is suppressed.
AIChE Journal, 1990
Numerical simulations of mass transfer into falling liquid films, both through the wavy interface... more Numerical simulations of mass transfer into falling liquid films, both through the wavy interface and from the wall, have been performed for experimentally measured large waves within which the flow fields have been computed. Experiments have shown that the occurrence of waves on free falling films causes dramatic increases in mass transfer into the film, even under laminar flow conditions. Wave effects have been modeled in several ways, none of which predicts the observed rate of enhancement. The present numerical procedure includes solving the convective-diffusion equation for wavy films by extending a technique developed for hydrodynamic simulation. The presence of waves is shown to cause significant velocities normal to each interface. In conjunction with recirculation within the large waves, these flow patterns produce transfer rates for large waves that are several times larger than predicted for quasiparallel velocity fields. Experimental wave structure data were used to define the dimensions and frequency of an average large wave and surrounding substrate. Computed transfer rates at both the gas-liquid interface and the wall for a film composed of a periodic sequence of average waves agree well with published data. These simulations confirm the inadequacy of parabolic, or Kapitza-type velocity profiles in formulating transport models.
AIChE Journal, 1988
The structure of the wavy interface on a falling liquid film is studied for conditions of counter... more The structure of the wavy interface on a falling liquid film is studied for conditions of countercurrent gas flow in order to investigate mechanisms for flooding. Measurements taken just below the liquid feed and at 1.7 m down the tube show that under all conditions, including flooding, the waves propagate only downward and are never of such amplitude as to bridge the tube. These observations are in contrast to speculations in the literature that upward flow of waves or bridging of liquid due to waves cause flooding. In the mechanism suggested, flooding is due to flow reversal in the film just at the liquid entry.
International Journal of Multiphase Flow, 1980