Seim Timung - Academia.edu (original) (raw)
Papers by Seim Timung
Lecture Notes in Mechanical Engineering
9TH NATIONAL CONFERENCE ON RECENT DEVELOPMENTS IN MECHANICAL ENGINEERING [RDME 2021], 2022
This book is based on my M. Tech work on prediction of flow patterns of gas-liquid flow in microc... more This book is based on my M. Tech work on prediction of flow patterns of gas-liquid flow in microchannel using probabilistic neural network (PNN). It also contains a brief description on PNN and steps to develop a PNN in MATLAB R2008a. The analytical models present in literature, to predict the gas-liquid flow patterns employs different physics involved. So, for each flow pattern there are separate models being developed. This present work is aim to develop a single PNN model for predicting the flow patterns. The advantage of using a PNN is the ability to predict without any detail knowledge and understanding of the physics involved.
Introduction: The study of multiphase flows inside the microfluidic devices have received much at... more Introduction: The study of multiphase flows inside the microfluidic devices have received much attention recently because of its variety of application related to heat and mass transfer, mixing, microreaction, and emulsification [1]. Many researchers have concentrated on the influence of flow rate of the fluids, fluid properties such as surface or interfacial tensions, contact angle and viscosity of the liquids on the interfacial morphologies and their transitions [2]. The results suggest that a host of interesting flow patterns can be achieved by controlling the fluid properties (interfacial tension, viscosity) and flow conditions (flow rate). Use of COMSOL Multiphysics: In the present study, we explore the pathways to control the flow morphologies of a liquid-liquid multiphase flow employing an external electrostatic field. The oil-water multiphase system is modelled employing the commercial software COMSOL MULTIPHYSICS. The electrohydrodynamics (EHD) of the multiphase system is n...
Journal of Colloid and Interface Science
Nanoscale Advances
A droplet energy harvester (DEH) composed of aqueous salt solution could generate electrical ener... more A droplet energy harvester (DEH) composed of aqueous salt solution could generate electrical energy from light when placed on metal-semiconductor Schottky-junction emulating the principles of electrochemical photovoltaics (ECPV). The maximum...
ELECTROPHORESIS, 2016
We report a facile and non-invasive way to disintegrate a microdroplet into a string of further m... more We report a facile and non-invasive way to disintegrate a microdroplet into a string of further miniaturized ones under the influence of an external electrohydrodynamic field inside a microchannel. The deformation and breakup of the droplet was engendered by the Maxwell's stress originating from the accumulation of induced and free charges at the oil-water interface. While at smaller field intensities, e.g. less than 1 MV/m, the droplet deformed into a plug, at relatively higher field intensities, e.g. ∼1.16 MV/m, a pair of droplets having opposite surface charge was formed. The charged droplets showed an interesting periodic bridging and breakup during their translation motion across the channel. For even higher field intensities, e.g. more than 1.2 MV/m, the entire droplet underwent dielectrophoresis towards one of the electrodes before experiencing a strong attractive force from the other electrode to deform into a shape of a Taylor cone. With progress in time, mimicking the electrospraying phenomenon, the cone-tip periodically ejected a string of miniaturized water droplets to form a microemulsion inside the channel. The frequency and size of the droplet ejection could be tuned by varying the applied field intensity. A water droplet of ∼214 μm diameter could continuously eject droplets of size ∼10 μm or even smaller to form a microemulsion inside the channel. This article is protected by copyright. All rights reserved.
ELECTROPHORESIS, 2016
Numerical simulations supplemented by experiments together uncovered that strategic integration o... more Numerical simulations supplemented by experiments together uncovered that strategic integration of discrete electric fields in a non-invasive manner could substantially miniaturize the droplets into smaller parts in a pressure driven oil-water flow inside microchannels. The Maxwell's stress generated from the electric field at the oil-water interface could deform, stretch, neck, pin, and disintegrate a droplet into many miniaturized daughter droplets, which eventually ushered a one-step method to form water-in-oil microemulsion employing microchannels. The interplay between electrostatic, inertial, capillary, and viscous forces led to various pathways of droplet breaking, namely, fission, cascade, or Rayleigh modes. While a localized electric field in the fission mode could split a droplet into a number of daughter droplets of smaller size, the cascade or the Rayleigh mode led to the formation of an array of miniaturized droplets when multiple electrodes generating different field intensities were ingeniously assembled around the microchannel. The droplets size and frequency could be tuned by varying the field intensity, channel diameter, electrode locations, interfacial tension, and flow ratio. The proposed methodology shows a simple methodology to transform a microdroplet into an array of miniaturized ones inside a straight microchannel for enhanced mass, energy, and momentum transfer, and higher throughput.
The flow morphology of two immiscible fluids in a microfluidic device finds numerous applications... more The flow morphology of two immiscible fluids in a microfluidic device finds numerous applications such as emulsification, synthesis of nanomaterials [1], lab-on-a-chip devices and biological analysis [2]. It offers many advantages over the conventional macroscopic devices because of its availability for higher surface to volume ratio, ability to handle small volume of fluids, easier process control and reduction in operating cost [3]. But the flows in such microscale devices are mostly influenced by surface and viscous forces, where gravitational and inertial forces have very less impact. Thus, large size flow structures such as slug and plug flow are often encountered, which may not be desirable for processes where higher degree of mixing is required. In this regard, it is very important to identify the flow conditions for developing smaller size flow structures with higher surface to volume ratio. Previous studies have accomplished these objectives by varying the velocity of fluid...
The Canadian Journal of Chemical Engineering, 2015
RSC Adv., 2015
An externally applied alternating current (AC) electrostatic field can deform the interface of a ... more An externally applied alternating current (AC) electrostatic field can deform the interface of a pair of weakly conducting liquids to engender droplet flow patterns inside the ‘T’ shaped microchannels.
Applied Soft Computing, 2013
ABSTRACT The present study attempts to develop a flow pattern indicator for gas–liquid flow in mi... more ABSTRACT The present study attempts to develop a flow pattern indicator for gas–liquid flow in microchannel with the help of artificial neural network (ANN). Out of many neural networks present in literature, probabilistic neural network (PNN) has been chosen for the present study due to its speed in operation and accuracy in pattern recognition. The inbuilt code in MATLAB R2008a has been used to develop the PNN. During training, superficial velocity of gas and liquid phase, channel diameter, angle of inclination and fluid properties such as density, viscosity and surface tension have been considered as the governing parameters of the flow pattern. Data has been collected from the literature for air–water and nitrogen–water flow through different circular microchannel diameters (0.53, 0.25, 0.100 and 0.050 mm for nitrogen–water and 0.53, 0.22 mm for air–water). For the convenience of the study, the flow patterns available in literature have been classified into six categories namely; bubbly, slug, annular, churn, liquid ring and liquid lump flow. Single PNN model is unable to predict the flow pattern for the whole range (0.53 mm–0.050 mm) of microchannel diameter. That is why two separate PNN models has been developed to predict the flow patterns of gas–liquid flow through different channel diameter, one for diameter ranging from 0.53 mm to 0.22 mm and another for 0.100 mm–0.05 mm. The predicted map and their transition boundaries have been compared with the corresponding experimental data and have been found to be in good agreement. Whereas accuracy in prediction of transition boundary obtained from available analytical models used for conventional channel is less for all diameter of channel as compared to the present work. The percentage accuracy of PNN (∼94% for 0.53 mm ID and ∼73% for 0.100 mm ID channel) has also been found to be higher than the model based on Weber number (∼86% for 0.53 mm ID and ∼36% for 0.05 mm ID channel).
Lecture Notes in Mechanical Engineering
9TH NATIONAL CONFERENCE ON RECENT DEVELOPMENTS IN MECHANICAL ENGINEERING [RDME 2021], 2022
This book is based on my M. Tech work on prediction of flow patterns of gas-liquid flow in microc... more This book is based on my M. Tech work on prediction of flow patterns of gas-liquid flow in microchannel using probabilistic neural network (PNN). It also contains a brief description on PNN and steps to develop a PNN in MATLAB R2008a. The analytical models present in literature, to predict the gas-liquid flow patterns employs different physics involved. So, for each flow pattern there are separate models being developed. This present work is aim to develop a single PNN model for predicting the flow patterns. The advantage of using a PNN is the ability to predict without any detail knowledge and understanding of the physics involved.
Introduction: The study of multiphase flows inside the microfluidic devices have received much at... more Introduction: The study of multiphase flows inside the microfluidic devices have received much attention recently because of its variety of application related to heat and mass transfer, mixing, microreaction, and emulsification [1]. Many researchers have concentrated on the influence of flow rate of the fluids, fluid properties such as surface or interfacial tensions, contact angle and viscosity of the liquids on the interfacial morphologies and their transitions [2]. The results suggest that a host of interesting flow patterns can be achieved by controlling the fluid properties (interfacial tension, viscosity) and flow conditions (flow rate). Use of COMSOL Multiphysics: In the present study, we explore the pathways to control the flow morphologies of a liquid-liquid multiphase flow employing an external electrostatic field. The oil-water multiphase system is modelled employing the commercial software COMSOL MULTIPHYSICS. The electrohydrodynamics (EHD) of the multiphase system is n...
Journal of Colloid and Interface Science
Nanoscale Advances
A droplet energy harvester (DEH) composed of aqueous salt solution could generate electrical ener... more A droplet energy harvester (DEH) composed of aqueous salt solution could generate electrical energy from light when placed on metal-semiconductor Schottky-junction emulating the principles of electrochemical photovoltaics (ECPV). The maximum...
ELECTROPHORESIS, 2016
We report a facile and non-invasive way to disintegrate a microdroplet into a string of further m... more We report a facile and non-invasive way to disintegrate a microdroplet into a string of further miniaturized ones under the influence of an external electrohydrodynamic field inside a microchannel. The deformation and breakup of the droplet was engendered by the Maxwell's stress originating from the accumulation of induced and free charges at the oil-water interface. While at smaller field intensities, e.g. less than 1 MV/m, the droplet deformed into a plug, at relatively higher field intensities, e.g. ∼1.16 MV/m, a pair of droplets having opposite surface charge was formed. The charged droplets showed an interesting periodic bridging and breakup during their translation motion across the channel. For even higher field intensities, e.g. more than 1.2 MV/m, the entire droplet underwent dielectrophoresis towards one of the electrodes before experiencing a strong attractive force from the other electrode to deform into a shape of a Taylor cone. With progress in time, mimicking the electrospraying phenomenon, the cone-tip periodically ejected a string of miniaturized water droplets to form a microemulsion inside the channel. The frequency and size of the droplet ejection could be tuned by varying the applied field intensity. A water droplet of ∼214 μm diameter could continuously eject droplets of size ∼10 μm or even smaller to form a microemulsion inside the channel. This article is protected by copyright. All rights reserved.
ELECTROPHORESIS, 2016
Numerical simulations supplemented by experiments together uncovered that strategic integration o... more Numerical simulations supplemented by experiments together uncovered that strategic integration of discrete electric fields in a non-invasive manner could substantially miniaturize the droplets into smaller parts in a pressure driven oil-water flow inside microchannels. The Maxwell's stress generated from the electric field at the oil-water interface could deform, stretch, neck, pin, and disintegrate a droplet into many miniaturized daughter droplets, which eventually ushered a one-step method to form water-in-oil microemulsion employing microchannels. The interplay between electrostatic, inertial, capillary, and viscous forces led to various pathways of droplet breaking, namely, fission, cascade, or Rayleigh modes. While a localized electric field in the fission mode could split a droplet into a number of daughter droplets of smaller size, the cascade or the Rayleigh mode led to the formation of an array of miniaturized droplets when multiple electrodes generating different field intensities were ingeniously assembled around the microchannel. The droplets size and frequency could be tuned by varying the field intensity, channel diameter, electrode locations, interfacial tension, and flow ratio. The proposed methodology shows a simple methodology to transform a microdroplet into an array of miniaturized ones inside a straight microchannel for enhanced mass, energy, and momentum transfer, and higher throughput.
The flow morphology of two immiscible fluids in a microfluidic device finds numerous applications... more The flow morphology of two immiscible fluids in a microfluidic device finds numerous applications such as emulsification, synthesis of nanomaterials [1], lab-on-a-chip devices and biological analysis [2]. It offers many advantages over the conventional macroscopic devices because of its availability for higher surface to volume ratio, ability to handle small volume of fluids, easier process control and reduction in operating cost [3]. But the flows in such microscale devices are mostly influenced by surface and viscous forces, where gravitational and inertial forces have very less impact. Thus, large size flow structures such as slug and plug flow are often encountered, which may not be desirable for processes where higher degree of mixing is required. In this regard, it is very important to identify the flow conditions for developing smaller size flow structures with higher surface to volume ratio. Previous studies have accomplished these objectives by varying the velocity of fluid...
The Canadian Journal of Chemical Engineering, 2015
RSC Adv., 2015
An externally applied alternating current (AC) electrostatic field can deform the interface of a ... more An externally applied alternating current (AC) electrostatic field can deform the interface of a pair of weakly conducting liquids to engender droplet flow patterns inside the ‘T’ shaped microchannels.
Applied Soft Computing, 2013
ABSTRACT The present study attempts to develop a flow pattern indicator for gas–liquid flow in mi... more ABSTRACT The present study attempts to develop a flow pattern indicator for gas–liquid flow in microchannel with the help of artificial neural network (ANN). Out of many neural networks present in literature, probabilistic neural network (PNN) has been chosen for the present study due to its speed in operation and accuracy in pattern recognition. The inbuilt code in MATLAB R2008a has been used to develop the PNN. During training, superficial velocity of gas and liquid phase, channel diameter, angle of inclination and fluid properties such as density, viscosity and surface tension have been considered as the governing parameters of the flow pattern. Data has been collected from the literature for air–water and nitrogen–water flow through different circular microchannel diameters (0.53, 0.25, 0.100 and 0.050 mm for nitrogen–water and 0.53, 0.22 mm for air–water). For the convenience of the study, the flow patterns available in literature have been classified into six categories namely; bubbly, slug, annular, churn, liquid ring and liquid lump flow. Single PNN model is unable to predict the flow pattern for the whole range (0.53 mm–0.050 mm) of microchannel diameter. That is why two separate PNN models has been developed to predict the flow patterns of gas–liquid flow through different channel diameter, one for diameter ranging from 0.53 mm to 0.22 mm and another for 0.100 mm–0.05 mm. The predicted map and their transition boundaries have been compared with the corresponding experimental data and have been found to be in good agreement. Whereas accuracy in prediction of transition boundary obtained from available analytical models used for conventional channel is less for all diameter of channel as compared to the present work. The percentage accuracy of PNN (∼94% for 0.53 mm ID and ∼73% for 0.100 mm ID channel) has also been found to be higher than the model based on Weber number (∼86% for 0.53 mm ID and ∼36% for 0.05 mm ID channel).