APS News

Fluid Researchers Gather for 1995 DFD Meeting

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.

New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer. New studies of various aspects of turbulence and the behavior of single strands of DNA in aqueous suspensions were among the highlights of the 1995 fall meeting of the APS Division of Fluid Dynamics, held 19-21 November in Irvine, California. More than 850 contributed papers were presented, in addition to several invited lectures. The meeting also featured the 13th Annual Gallery of Fluid Motion, an exhibit of contributed photographs and videos of experimental fluid dynamics. Outstanding entries, selected for originality and their ability to convey and exchange information, will appear in the September 1996 issue of Physics of Fluids.

Breakdown Into Turbulence of Propagating Internal Waves. Internal waves are ubiquitous phenomena in the stably-stratified regions of the atmosphere and oceans, and it is thought that much of the turbulence in these regions is due to the breakdown into turbulence of these waves, according to James Riley of the University of Washington. As examples, he offered internal wave breakdown as playing a major role in the overall mixing and resultant diapycnal heat and mass transfer in oceans. Atmospheric wave breakdown is considered a source of clear air turbulence and provides a potentially important mechanism for the exchange of tropospheric and stratospheric air mass.

He has concluded from stability analysis that internal waves are unstable, even at small amplitudes, due to a parametric resonance. Riley's observations revealed that wave breakdown often occurs through wave intensification and steepening caused, for example, by interaction with ambient currents, or by reflection off sloping terrain.

Viscoelastic DNA Suspensions. Recent experiments at AT&T Bell Laboratories on the behavior of single DNA strands in aqueous suspensions have shown that the molecular relaxation can often endow such fluids with a viscoelastic time of seconds, with a viscosity similar to that of water. According to AT&T's Paul Kolodner, this has opened the way to experimental observation of oscillatory convective states resulting from viscoelasticity. Performed in a long, narrow, annular convection cell, the experiments revealed that the traveling waves (which represented the flow patterns) are much slower than expected: the oscillation periods are hours, while the relaxation times are typically 30 seconds.

Turbulence Stress Tensors. Turbulence subgrid-scale stresses - defined as the difference between spatially filtered momentum fluxes and momentum fluxes of large scales - are random variables that must be parametrized in terms of large-scale quantities. C. Meneveau of Johns Hopkins University discussed how hyperviscosity and non-local eddy-viscosity models can be motivated by more general constraints than the specific correlation functions usually associated with the function.

Meneveau studied the response of subgrid-scale stresses to a rapidly applied, irrotational straining field through a series of experiments in a water-tank, in which quasi-isotropic turbulence was subjected to rapid axisymmetric expansion.

Optical Studies of Wall Turbulence. According to the University of Illinois' R.J. Adrian, techniques based on particle image velocimetry for the measurement of velocity fields make is possible to observe spatial scales over more than two decades, a sufficient range in which to observe the large and small scales of turbulence simultaneously. Adrian reported on a number of different experiments on wall flows, such as pipe flow and channel flow, which afforded direct observation of the form of various fundamental structural elements at elevated Reynolds numbers, often for the first time.

New Prospects for Lagrangian Methods. A. Leonard of the California Institute of Technology reviewed recent efforts to develop a robust vortex particle method for two- and three-dimensional, incompressible flows. His scheme includes a novel treatment of viscous effects to allow for the accurate representation of boundary layer mechanics, including unsteady separation.

Prize and Award Lectures. In addition to the regular technical program, three APS prize recipients gave lectures at the meeting. Harry Swinney (University of Texas at Austin), recipient of the 1995 APS Fluid Dynamics Prize, spoke on anomalous diffusion and Levy flights in quaigeostrophic flow. The 1995 Otto LaPorte Award recipient, Katepalli Sreenivasan of Yale University, spoke on multifractals and turbulence. Joseph A. Johnson III, recipient of the 1995 Boucher Award (formerly the Minority Lectureship Award) spoke on natural turbulence closure in a supersonic free shear layer.


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