Idris Adebayo - Academia.edu (original) (raw)

Papers by Idris Adebayo

arXiv (Cornell University), Jul 23, 2020

Nigerian Journal of Technological Research, 2017

In demonstration of the effectiveness of immobilized Moringa oleifera (M. oleifera) leaves (IMOL)... more In demonstration of the effectiveness of immobilized Moringa oleifera (M. oleifera) leaves (IMOL) for the removal of metal ions from wastewater, the leaves of M. Oleifera were immobilized by entrapping them within a polymeric matrix of calcium alginate. The concentration of residual metal ions after sorption was determined using atomic absorption spectrophotometer (AAS). The result of sorption capacity of Cd 2+ , Cu 2+ and Pb 2+ were found to be 99.59±0.061, 99.58±0.063 and 46.15±0.032% respectively . There was an increase in sorption capacity as contact time, pH and initial metal ion concentration increased, and decrease in sorption capacity as ionic strength increased. The possibility of M. oleifera leaves to absorb Cd 2+ , Cu 2+ and Pb 2+ proved the result as an effective technology for wastewater treatment and cheaper means of metal ion removal from wastewater compared to other standard methods. Keywords : M. oleifera leaves, immobilization, sorption capacity, metal ions Cite th...

Environmental Fluid Mechanics, 2022

In this article, we present a full three-dimensional numerical study of thin liquid films falling... more In this article, we present a full three-dimensional numerical study of thin liquid films falling on a vertical surface, by solving the full three-dimensional Navier–Stokes equations with a hybrid front-tracking/level-set method for tracking the interface. General falling film flow applications span across many types of process industries but also occur in a multitude of natural and environmental applications such as ice sheets, glaciology and even volcanic lava flows. In this study, we propose three configurations of falling films. Two of them, with small and moderate Reynolds number, are set to mimic pulsed and forced falling film types inside a minimum periodic domain, able to cover entirely the temporal evolution of a single wave. The latest example, corresponding to a high Reynolds number, is initialised with a flat interface without any specific perturbations. For the first time, this study highlights the natural transition from a non-deformed interface to its first streamwise...

Bulletin of the American Physical Society, 2017

Submitted for the DFD16 Meeting of The American Physical Society Doubly-excited pulse-waves on fl... more Submitted for the DFD16 Meeting of The American Physical Society Doubly-excited pulse-waves on flowing liquid films: experiments and numerical simulations1 IDRIS ADEBAYO, ZHIHUA XIE, Imperial College London, ZHIZHAO CHE, Tianjin University, China, ALEX WRAY, OMAR MATAR, Imperial College London — The interaction patterns between doublyexcited pulse waves on a flowing liquid film are studied both experimentally and numerically. The flowing film is constituted on an inclined glass substrate while pulse-waves are excited on the film surface by means of a solenoid valve connected to a relay which receives signals from customised Matlab routines. The effect of varying the system parameters i.e. film flow rate, inter-pulse interval and substrate inclination angle on the pulse interaction patterns are then studied. Results show that different interaction patterns exist for these binary pulses; which include a singular behaviour, complete merger, partial merger and total non-coalescence. A r...

Bulletin of the American Physical Society, 2017

Bulletin of the American Physical Society, 2016

London-The interaction patterns between doublyexcited pulse waves on a flowing liquid film are st... more London-The interaction patterns between doublyexcited pulse waves on a flowing liquid film are studied both experimentally and numerically. The flowing film is constituted on an inclined glass substrate while pulse-waves are excited on the film surface by means of a solenoid valve connected to a relay which receives signals from customised Matlab routines. The effect of varying the system parameters i.e. film flow rate, inter-pulse interval and substrate inclination angle on the pulse interaction patterns are then studied. Results show that different interaction patterns exist for these binary pulses; which include a singular behaviour, complete merger, partial merger and total non-coalescence. A regime map of these patterns is then plotted for each inclination angles examined, based on the film Re and the inter-pulse interval. Finally, the individual effect of the system parameters on the merging distance of these binary pulses in the merger mode is then studied and the results validated using both numerical simulations and mathematical modelling.

Droplet impact on flowing liquid films constitutes an important research area due to its manifold... more Droplet impact on flowing liquid films constitutes an important research area due to its manifold applications both in industry and day-today living. Previous studies have, however, ignored the contributions of stochastic waves to the drop impact dynamics. In this project, an experimental study of droplet impact on controlled flowing liquid films is carried out. The aim of the study is to provide an understanding of the contributions of the spatial structures of waves to drop impact dynamics on flowing films. The experimental facility consists of a falling film rig which comprises film flow, film control, and droplet-generation units, as well as a high-speed imaging system. In a preliminary study, the effect of film control on the dominant wave propagation modes is investigated. Two classes of waves are identified, namely the gamma I and II wave families, which are characterised both qualitatively and quantitatively and confirmed to be in good agreement with previous studies in the literature. Studies on the interaction patterns between doubly-excited planar pulse waves on an uncontrolled flowing film surface are then carried out to provide insight into the interaction patterns of waveforms on flowing liquid films. Distinct interaction modes are found to be of central importance to understanding the complex wave interactions which could lead to interfacial 'turbulence'. The effect of film control on the impact dynamics of both low and highinertia drops is then studied. In both studies, the impact surface is divided into the "wave hump", "flat film", and "capillary waves" regions. For low-inertia drop impacts, film control is observed to have a qualitative and quantitative effect on the length of liquid columns formed in a partial coalescence outcome, the pinch-off time, as well as the size of the ejected daughter droplets. Qualitative differences included a complete change of the outcome, with other outcomes such as 'bouncing', 'sliding', and 'total coalescence' observed in the low-inertia drop impact scenario. For high-inertia drop impacts, the effect of film control is studied in the morphology of the crown produced in a splash outcome as well as the distinctive attributes of the ejected droplets.

NaOH, Ca(OH) 2 and Na 2 CO 3 were used as the precipitants in this study. The reaction time was s... more NaOH, Ca(OH) 2 and Na 2 CO 3 were used as the precipitants in this study. The reaction time was set at 45 min, temperature at 50o C, pH at 9 for the hydroxides and 10 for the carbonate. Heavy metal ions precipitated includes; Pb 2+ , Cu 2+ , Mn 2+ , Zn 2+ and Fe 3+ . NaOH exhibited highest precipitation for Cu 2+ (99.2 %) and least for Zn 2+ (75.2 %), Ca(OH) 2 exhibited highest precipitation for Cu 2+ (100 %) and least for Pb 2+ (71.9 %), while Na 2 CO 3 exhibited highest precipitation for Fe 3+ (97.6 %) and least for Pb 2+ (75 %). The precipitation of all the heavy metals ions were also compared for the precipitants. All precipitant are capable of removing at least 70% of the heavy metal ions studied form their aqueous solution while a narrow selection might take the value as high as 100%, hence showing adequate potentials of the precipitants in the removal of aqueous heavy metal ions at the set conditions form wastewater prior to discharge into sewerage.

Bulletin of the American Physical Society, 2015

speed photography. The flowing liquid films are generated on an inclined substrate. The flow rate... more speed photography. The flowing liquid films are generated on an inclined substrate. The flow rate of the liquid film, the inclination angle, and the droplet speed are controlled and their effects on the splashing process studied. Due to the flow in the liquid film and the oblique impact direction, the splashing process is asymmetric. The propagation of the asymmetric crown and the generation of secondary droplets on the rim of the crown are analysed through image processing. The results show that the flow in the liquid films significantly affects the propagation of the liquid crown and the generation of secondary droplets.

Bulletin of the American Physical Society, 2016

is applied to ensure that droplet impact occurs on different, targeted regions of a controlled fi... more is applied to ensure that droplet impact occurs on different, targeted regions of a controlled film surface viz. capillary waves preceding a large-amplitude wave, flat film regions, and wave humps. The outcomes of droplet impact on these different regions are then compared and the differences discussed. The effect of varying the film flow rate, droplet speed, and droplet size on a number of droplet impact outcomes is also studied and the results further compared with those from uncontrolled as well as quiescent liquid films.

Bulletin of the American Physical Society, 2017

study the outcome of droplet impact on controlled flowing liquid films using a massively-parallel... more study the outcome of droplet impact on controlled flowing liquid films using a massively-parallelised three-dimensional simulation code Blue. The code utilises a domain-decomposition strategy for parallelization with MPI, while the fluid interface solver is based on a parallel implementation of a hybrid front-tracking/level set method. We control the film surface dynamics by an application of periodic inlet-forcing of the film flowrate, which ensures that droplet impact occurs on different, targeted regions of spatio-temporal regularly forming solitary waves, namely flat film, wave humps and capillary waves preceding a largeamplitude wave. The uniqueness and differences between outcomes obtained on these individual regions are then compared qualitatively and quantitatively. Finally, the individual contributions of the film flow rate, droplet speed, and droplet size on the droplet impact outcomes are also studied, and the results validated against previous experimental studies.

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic ... more Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

Journal of Visualized Experiments, 2018

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic ... more Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

Soft Matter, 2017

Waves! Spatial structures on flowing liquid films contribute immensely to drop impact dynamics an... more Waves! Spatial structures on flowing liquid films contribute immensely to drop impact dynamics and notably alter the impact outcomes.

Physical Review E, 2017

The interaction patterns between doubly excited pulse waves on thin liquid films flowing down an ... more The interaction patterns between doubly excited pulse waves on thin liquid films flowing down an inclined plane are studied both experimentally and numerically. The effect of varying the film flow rate, interpulse interval, and substrate inclination angle on the pulse interaction patterns is examined. Our results show that different interaction patterns exist for these binary pulses, which include solitary wave behavior, partial or complete pulse coalescence, and pulse noncoalescence. A regime map of these patterns is plotted for each inclination angle examined, parametrized by the film Reynolds number and interpulse interval. Finally, the individual effect of the system parameters mentioned above on the coalescence distance of binary pulses in the "complete pulse coalescence" mode is studied; the results are compared to numerical simulations of the two-dimensional Navier-Stokes equations yielding good agreement.

AIAA Journal, 1991

A numerical model is developed for the investigation of boundary-layer transition control of spat... more A numerical model is developed for the investigation of boundary-layer transition control of spatially evolving instability waves. Active control of a periodically forced boundary layer in an incompressible fluid is simulated using surface beating techniques. The Navier-Stokes and energy equations are solved using a fully implicit finite-difference/spectral method. Temperature perturbations are introduced locally along finite heater strips to directly attenuate instability waves in the flow. A Feedback control loop is employed in which a downstream sensor is used to monitor wall shear stress fluctuations

arXiv (Cornell University), Jul 23, 2020

Nigerian Journal of Technological Research, 2017

In demonstration of the effectiveness of immobilized Moringa oleifera (M. oleifera) leaves (IMOL)... more In demonstration of the effectiveness of immobilized Moringa oleifera (M. oleifera) leaves (IMOL) for the removal of metal ions from wastewater, the leaves of M. Oleifera were immobilized by entrapping them within a polymeric matrix of calcium alginate. The concentration of residual metal ions after sorption was determined using atomic absorption spectrophotometer (AAS). The result of sorption capacity of Cd 2+ , Cu 2+ and Pb 2+ were found to be 99.59±0.061, 99.58±0.063 and 46.15±0.032% respectively . There was an increase in sorption capacity as contact time, pH and initial metal ion concentration increased, and decrease in sorption capacity as ionic strength increased. The possibility of M. oleifera leaves to absorb Cd 2+ , Cu 2+ and Pb 2+ proved the result as an effective technology for wastewater treatment and cheaper means of metal ion removal from wastewater compared to other standard methods. Keywords : M. oleifera leaves, immobilization, sorption capacity, metal ions Cite th...

Environmental Fluid Mechanics, 2022

In this article, we present a full three-dimensional numerical study of thin liquid films falling... more In this article, we present a full three-dimensional numerical study of thin liquid films falling on a vertical surface, by solving the full three-dimensional Navier–Stokes equations with a hybrid front-tracking/level-set method for tracking the interface. General falling film flow applications span across many types of process industries but also occur in a multitude of natural and environmental applications such as ice sheets, glaciology and even volcanic lava flows. In this study, we propose three configurations of falling films. Two of them, with small and moderate Reynolds number, are set to mimic pulsed and forced falling film types inside a minimum periodic domain, able to cover entirely the temporal evolution of a single wave. The latest example, corresponding to a high Reynolds number, is initialised with a flat interface without any specific perturbations. For the first time, this study highlights the natural transition from a non-deformed interface to its first streamwise...

Bulletin of the American Physical Society, 2017

Submitted for the DFD16 Meeting of The American Physical Society Doubly-excited pulse-waves on fl... more Submitted for the DFD16 Meeting of The American Physical Society Doubly-excited pulse-waves on flowing liquid films: experiments and numerical simulations1 IDRIS ADEBAYO, ZHIHUA XIE, Imperial College London, ZHIZHAO CHE, Tianjin University, China, ALEX WRAY, OMAR MATAR, Imperial College London — The interaction patterns between doublyexcited pulse waves on a flowing liquid film are studied both experimentally and numerically. The flowing film is constituted on an inclined glass substrate while pulse-waves are excited on the film surface by means of a solenoid valve connected to a relay which receives signals from customised Matlab routines. The effect of varying the system parameters i.e. film flow rate, inter-pulse interval and substrate inclination angle on the pulse interaction patterns are then studied. Results show that different interaction patterns exist for these binary pulses; which include a singular behaviour, complete merger, partial merger and total non-coalescence. A r...

Bulletin of the American Physical Society, 2017

Bulletin of the American Physical Society, 2016

London-The interaction patterns between doublyexcited pulse waves on a flowing liquid film are st... more London-The interaction patterns between doublyexcited pulse waves on a flowing liquid film are studied both experimentally and numerically. The flowing film is constituted on an inclined glass substrate while pulse-waves are excited on the film surface by means of a solenoid valve connected to a relay which receives signals from customised Matlab routines. The effect of varying the system parameters i.e. film flow rate, inter-pulse interval and substrate inclination angle on the pulse interaction patterns are then studied. Results show that different interaction patterns exist for these binary pulses; which include a singular behaviour, complete merger, partial merger and total non-coalescence. A regime map of these patterns is then plotted for each inclination angles examined, based on the film Re and the inter-pulse interval. Finally, the individual effect of the system parameters on the merging distance of these binary pulses in the merger mode is then studied and the results validated using both numerical simulations and mathematical modelling.

Droplet impact on flowing liquid films constitutes an important research area due to its manifold... more Droplet impact on flowing liquid films constitutes an important research area due to its manifold applications both in industry and day-today living. Previous studies have, however, ignored the contributions of stochastic waves to the drop impact dynamics. In this project, an experimental study of droplet impact on controlled flowing liquid films is carried out. The aim of the study is to provide an understanding of the contributions of the spatial structures of waves to drop impact dynamics on flowing films. The experimental facility consists of a falling film rig which comprises film flow, film control, and droplet-generation units, as well as a high-speed imaging system. In a preliminary study, the effect of film control on the dominant wave propagation modes is investigated. Two classes of waves are identified, namely the gamma I and II wave families, which are characterised both qualitatively and quantitatively and confirmed to be in good agreement with previous studies in the literature. Studies on the interaction patterns between doubly-excited planar pulse waves on an uncontrolled flowing film surface are then carried out to provide insight into the interaction patterns of waveforms on flowing liquid films. Distinct interaction modes are found to be of central importance to understanding the complex wave interactions which could lead to interfacial 'turbulence'. The effect of film control on the impact dynamics of both low and highinertia drops is then studied. In both studies, the impact surface is divided into the "wave hump", "flat film", and "capillary waves" regions. For low-inertia drop impacts, film control is observed to have a qualitative and quantitative effect on the length of liquid columns formed in a partial coalescence outcome, the pinch-off time, as well as the size of the ejected daughter droplets. Qualitative differences included a complete change of the outcome, with other outcomes such as 'bouncing', 'sliding', and 'total coalescence' observed in the low-inertia drop impact scenario. For high-inertia drop impacts, the effect of film control is studied in the morphology of the crown produced in a splash outcome as well as the distinctive attributes of the ejected droplets.

NaOH, Ca(OH) 2 and Na 2 CO 3 were used as the precipitants in this study. The reaction time was s... more NaOH, Ca(OH) 2 and Na 2 CO 3 were used as the precipitants in this study. The reaction time was set at 45 min, temperature at 50o C, pH at 9 for the hydroxides and 10 for the carbonate. Heavy metal ions precipitated includes; Pb 2+ , Cu 2+ , Mn 2+ , Zn 2+ and Fe 3+ . NaOH exhibited highest precipitation for Cu 2+ (99.2 %) and least for Zn 2+ (75.2 %), Ca(OH) 2 exhibited highest precipitation for Cu 2+ (100 %) and least for Pb 2+ (71.9 %), while Na 2 CO 3 exhibited highest precipitation for Fe 3+ (97.6 %) and least for Pb 2+ (75 %). The precipitation of all the heavy metals ions were also compared for the precipitants. All precipitant are capable of removing at least 70% of the heavy metal ions studied form their aqueous solution while a narrow selection might take the value as high as 100%, hence showing adequate potentials of the precipitants in the removal of aqueous heavy metal ions at the set conditions form wastewater prior to discharge into sewerage.

Bulletin of the American Physical Society, 2015

speed photography. The flowing liquid films are generated on an inclined substrate. The flow rate... more speed photography. The flowing liquid films are generated on an inclined substrate. The flow rate of the liquid film, the inclination angle, and the droplet speed are controlled and their effects on the splashing process studied. Due to the flow in the liquid film and the oblique impact direction, the splashing process is asymmetric. The propagation of the asymmetric crown and the generation of secondary droplets on the rim of the crown are analysed through image processing. The results show that the flow in the liquid films significantly affects the propagation of the liquid crown and the generation of secondary droplets.

Bulletin of the American Physical Society, 2016

is applied to ensure that droplet impact occurs on different, targeted regions of a controlled fi... more is applied to ensure that droplet impact occurs on different, targeted regions of a controlled film surface viz. capillary waves preceding a large-amplitude wave, flat film regions, and wave humps. The outcomes of droplet impact on these different regions are then compared and the differences discussed. The effect of varying the film flow rate, droplet speed, and droplet size on a number of droplet impact outcomes is also studied and the results further compared with those from uncontrolled as well as quiescent liquid films.

Bulletin of the American Physical Society, 2017

study the outcome of droplet impact on controlled flowing liquid films using a massively-parallel... more study the outcome of droplet impact on controlled flowing liquid films using a massively-parallelised three-dimensional simulation code Blue. The code utilises a domain-decomposition strategy for parallelization with MPI, while the fluid interface solver is based on a parallel implementation of a hybrid front-tracking/level set method. We control the film surface dynamics by an application of periodic inlet-forcing of the film flowrate, which ensures that droplet impact occurs on different, targeted regions of spatio-temporal regularly forming solitary waves, namely flat film, wave humps and capillary waves preceding a largeamplitude wave. The uniqueness and differences between outcomes obtained on these individual regions are then compared qualitatively and quantitatively. Finally, the individual contributions of the film flow rate, droplet speed, and droplet size on the droplet impact outcomes are also studied, and the results validated against previous experimental studies.

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic ... more Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

Journal of Visualized Experiments, 2018

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic ... more Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

Soft Matter, 2017

Waves! Spatial structures on flowing liquid films contribute immensely to drop impact dynamics an... more Waves! Spatial structures on flowing liquid films contribute immensely to drop impact dynamics and notably alter the impact outcomes.

Physical Review E, 2017

The interaction patterns between doubly excited pulse waves on thin liquid films flowing down an ... more The interaction patterns between doubly excited pulse waves on thin liquid films flowing down an inclined plane are studied both experimentally and numerically. The effect of varying the film flow rate, interpulse interval, and substrate inclination angle on the pulse interaction patterns is examined. Our results show that different interaction patterns exist for these binary pulses, which include solitary wave behavior, partial or complete pulse coalescence, and pulse noncoalescence. A regime map of these patterns is plotted for each inclination angle examined, parametrized by the film Reynolds number and interpulse interval. Finally, the individual effect of the system parameters mentioned above on the coalescence distance of binary pulses in the "complete pulse coalescence" mode is studied; the results are compared to numerical simulations of the two-dimensional Navier-Stokes equations yielding good agreement.

AIAA Journal, 1991

A numerical model is developed for the investigation of boundary-layer transition control of spat... more A numerical model is developed for the investigation of boundary-layer transition control of spatially evolving instability waves. Active control of a periodically forced boundary layer in an incompressible fluid is simulated using surface beating techniques. The Navier-Stokes and energy equations are solved using a fully implicit finite-difference/spectral method. Temperature perturbations are introduced locally along finite heater strips to directly attenuate instability waves in the flow. A Feedback control loop is employed in which a downstream sensor is used to monitor wall shear stress fluctuations