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Papers by Shubham Srivastava

8th U.S. National Combustion Meeting, 2013

An opposed laminar flow flame formed with methane/acetylene and oxygen enriched-air was employed ... more An opposed laminar flow flame formed with methane/acetylene and oxygen enriched-air was employed to produce molybdenum oxide nanostructures directly in the gas phase. The composition of the fuel and oxidizer to form the flame was 96%CH 4 +4%C 2 H 2 and 50%O 2 /50%N 2 , respectively. Raw material was introduced into oxidizer side of the flame in the form of solid molybdenum wires with 99% purity. The high temperature and the oxygen rich chemical environment of the flame resulted in fast surface oxidation of the probes and material etching from their surfaces. Upon their interaction with the flame, the probes generated molybdenum trioxide vapors. The vapors were transported in the direction of the stagnation plane of the flame and reduced to molybdenum dioxide as they entered the low temperature fuel rich zone. The velocity gradient and thermophoretic forces in the flame affected the transport of the molybdenum dioxide precursors. These precursors in the gas phase formed nanostructures that were thermophoretically collected from the flame volume. Essential morphological variations of generated nanomaterials were observed depending on flame and probe parameters. The distance of the collection plane from the molybdenum probe also played an important role in the morphology of generated nanoforms. The molybdenum probes with diameters of 0.75 mm and 1 mm were used to achieve two distinct synthesis conditions. The variation of probe diameter affected probe temperature and resulted in different supersaturation levels of molybdenum dioxide vapors. Experiments with 1.0 mm diameter corresponded to lower supersaturation levels and resulted in the synthesis of well-defined convex polyhedron nanocrystals and nanorods. Higher material etching rates and, hence, supersaturation levels were obtained with 0.75 mm diameter probes. These conditions resulted in synthesis of mainly spherical molybdenum oxide nanomaterials agglomerated in soot-like fractal aggregates. The effect of flame parameters and material concentration on shape and structure of generated nanomaterial is also studied numerically. The underlying mechanisms governing the morphological variation of molybdenum oxide nanocrystals are analyzed using the following steps: monomers formation, nucleation, and growth. The nucleation model is based on the classical nucleation theory, and the growth model considers agglomeration and diffusion in the varying thermal environment using thermophoretic analysis. The model predictions are in good qualitative agreement with the experimental data.

Computers & Fluids, 2013

A multi-scale approach for coupling a coarse-grained (CG) deterministic solution for a reacting f... more A multi-scale approach for coupling a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution is proposed. The model includes a CG solution for the mass density and momentum and a FG solution for the temperature. A model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. A common variable is obtained from these solutions based on a CG density field defined from continuity on the coarse scales and the spatial filtering of the density derived from the state equation in the FG solution. Kalman filtering is used to combine these two solutions. The resulting CG density is both smooth and steered by heat release from the FG solution. The algorithm is demonstrated on a 1D model combining continuity and the Burgers' equation for the CG solution and the temperature equation with heat release for the FG solution. The results establish the feasibility of Kalman filtering in coupling deter-ministic CG solutions and stochastic FG solutions in reacting flow applications.

Proceedings of the Combustion Institute, 2015

A laminar counter-flow diffusion flame formed with methane/acetylene and oxygen enriched-air was ... more A laminar counter-flow diffusion flame formed with methane/acetylene and oxygen enriched-air was used for controlled synthesis of 1-D molybdenum oxide nanostructures directly in the gas phase. Raw material was introduced into the oxidizer side of the flame in the form of solid molybdenum wires with ~99% purity. Molybdenum oxide vapors formed in the gas phase were transported by the gas flow in the flame environment possessing strong thermal and chemical gradients. The generated nanostructures were collected thermophoretically from the flame volume. Essential morphological variations of generated nanomaterials were observed depending on sampling position within the flame volume and probe parameters. The mechanism behind the synthesis of the spherical and 1-D nanoforms is analyzed and modeled numerically. The nanorod growth model involves monomer transport, nucleation and growth. The monomer formation is through the oxidation and vaporization of the probe material. The nucleation model is based on the classical nucleation theory. The model predicts the trajectory and growth of the formed nuclei as they are transported in the flame volume. It is considered that the ends of the cylindrical 1-D nanorods grow by the phenomenon of rough growth while the lateral faces exhibit layered growth. The growth model also considers the contribution of the monomers diffusing on the nanoparticle surface as well as the effect of the atoms impinging directly onto the growth sites and compares their relative contributions. The model qualitatively predicts the variation of aspect ratio of the formed nanomaterials with increase of monomer concentration as observed in the experiments.

International Journal for Multiscale Computational Engineering, 2017

The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting... more The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution. The proposed method investigates the feasibility of implementing a multiscale approach for turbulent reacting flows based on large-eddy simulation (LES) coupled with a low-dimensional fine-grained stochastic solution for the subfilter scales reaction and transport. In this study, a model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. The solution for the continuity and momentum (the Burgers' equation) equations are implemented in 1D. The filtered densities obtained through the FG and the CG solutions are combined using the particle filter to obtain an updated density for the coarse solution that combines the effects of heat release (from the FG solution) and flow dynamics (from the CG solution). The results demonstrate that the particle filter may be a viable tool to couple deterministic CG solutions and stochastic FG solutions in reacting flow applications.

The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting... more The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution. The proposed method investigates the feasibility of implementing a multiscale approach for turbulent reacting flows based on largeeddy simulation (LES) coupled with a low-dimensional fine-grained stochastic solution for the subfilter scales reaction and transport. In this study, a model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. The solution for the continuity and momentum (the Burgers' equation) equations are implemented in 1D. The filtered densities obtained through the FG and the CG solutions are combined using the particle filter to obtain an updated density for the coarse solution that combines the effects of heat release (from the FG solution) and flow dynamics (from the CG solution). The results demonstrate that the particle filter may be a viable tool to couple deterministic CG solutions and stochastic FG solutions in reacting flow applications.

Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2019

The injection of choked gaseous jets into the still air is investigated experimentally motivated ... more The injection of choked gaseous jets into the still air is investigated experimentally motivated by many industrial applications including flares and burners. The objective is to study the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air, seeded with water fog. The computational methods consisted of 7.7 million cells simulation using Star CCM+. The test conditions include injection angles of 0°, 15°, and 30°. The results including mean and fluctuating velocities and the flow vorticity are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

AIAA SciTech, 2020

The injection of choked gaseous jets into still air is investigated computationally and experimen... more The injection of choked gaseous jets into still air is investigated computationally and experimentally. The objective is to compare the performance of three turbulence models-Realizable k-, SST k- and Reynolds Stress Transport to resolve the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air that has been seeded with water fog. The test conditions include injection angles of 0° and 15°. The results including jet velocities and the vorticity field are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

 Study and understand the physics underlying the controlled synthesis of 1-D metal oxide nanostr... more  Study and understand the physics underlying the controlled synthesis of 1-D metal oxide nanostructures in the gas phase using the Flame Gradient Method  Numerically simulate the growth characteristics of nanorods in the flame environment  Simulate the variation in the morphology of the nanoparticles with the change in the synthesis conditions.

An Ensemble Kalman Filter (EnKF) algorithm has been developed and implemented on chaotic Lorenz 6... more An Ensemble Kalman Filter (EnKF) algorithm has been developed and implemented on chaotic Lorenz 63 model. The EnKF has been given noisy data and used to find the optimum state of the system. The EnKF output has been compared to the actual output.

A dynamic 1D mathematical model is set up to simulate the formation of vescicle traps in fast axo... more A dynamic 1D mathematical model is set up to simulate the formation of vescicle traps in fast axonal transport occuring in neurons. The model developed helps in understanding how organelle polarity mismatch leads to formation of organelle traps and how, as a consequence axonal transport is affected. The model is solved using the COMSOL multiphysics package. The results show that the organelle build up in the traps leading to jams takes a long time. The time taken to reach steady state is around 150s as compared to 30s for normal healthy axon.

To understand the effect of various engine parameters, chiefly compression ratio on the C.I. comb... more To understand the effect of various engine parameters, chiefly compression ratio on the C.I. combustion, it was decided to develop a mathematical simulation for a single cylinder diesel engine fueled with diesel. The model will predict all the working characteristics of the engine like pressure, temperature and the cylinder volume at each crank angle and thermal efficiency. A separate mathematical code has also been developed which can predict the mole fractions of twelve equilibrium species formed during combustion with any type of fuel. The program also predicts changes in Cp, Cv, enthalpy, gas constant and molecular weight of the exhaust gas.

For better efficiency of any component the wear of the component should be minimized. It is well ... more For better efficiency of any component the wear of the component should be minimized. It is well known that the presence of residual compressive stress in a component reduces wear and crack initiation. Here an attempt has been made to induce residual compressive stress in Aluminium AA6063-T6 samples through ‘Oil Jet Peening’. Friction and wear characteristics of the peened component were evaluated using cylindrical specimens in a pin-on-disc sliding apparatus under dry conditions.

"Konkan Railway is developing an Anti Collision Device using Global Positioning System. This devi... more "Konkan Railway is developing an Anti Collision Device using Global Positioning System. This device will cost Rs 350 million just for the Konkan track and Rs 16 billion for the entire country network. It is a complex system and very costly for a country like ours.
Here we attempt to develop an Anti Collision System which is cost effective, simpler and works perfectly in all conditions.
We have used pressure sensors, micro controllers, transmitters and receivers to develop our system. The entire railway network has been divided into zones and each train communicates with the controller of the zone which monitors its position and prevents accident.
Our system does not require GPS, uses indigenous technology and is very cheap.
Every collision situation has been tested by a computer software.
Signals and railway crossings can also be controlled by this system."

Thesis Chapters by Shubham Srivastava

North Carolina State University, 2014

The past few decades have seen a great amount of interest in the field of nanotechnology. As our ... more The past few decades have seen a great amount of interest in the field of nanotechnology. As our world moves towards miniaturized devices nanotechnology is set to revolutionize the electronics, storage and sensing industry. Various methods for synthesis of different types of nanoparticles are being explored. A few of these processes that hold great promise for the future are the flame synthesis methods. These methods are highly efficient but at the same time it is difficult to control the morphology of the produced nanoparticles due to a high number of control parameters involved because of the complex flow processes. These issues demand a better understanding before these processes can be exploited to their maximum
potential.
Most numerical methods developed cater to the simulation of spherical nanoparticles.
However, it is now being increasingly understood that the shape and structure of a nanoparticle plays critical role in determining its chemical, physical and electronic properties. Therefore a high level of control on the shape of nanoparticles is highly imperative. With this purpose in mind this work proposes a novel numerical scheme to simulate the synthesis of one-dimensional nanorods and further presents mathematical simulations based on it followed by validation with experimental results.
The ability to predict the morphology of a nanoparticle formed by a synthesis process adds a distinct advantage. Therefore, intricate solutions have been found for the fluid flow and these have been coupled to each stage of nanoparticle development, namely monomer formation, nucleation, particle growth and particle transport. The numerical scheme takes into account all the details of the complex surface phenomena taking place on a nanorod. Later, factors are studied which transition the growth characteristics of a nanoparticle from one dimensional to a spherical structure, thus encompassing all the factors that influence the particle shape.
Group characteristics of nanoparticles have also been modeled by employing methods that track the growth of the entire set of nanoparticles in the flame volume. This gives a clear picture of the growth of the particle ensemble in addition to the individual particles.
This work provides a first of its kind numerical model for one-dimensional growth of nanoparticles and establishes the control parameters to achieve controlled growth of nanorods in flames

North Carolina State University, 2011

A multi-scale combustion model involving the Kalman and Particle filters is developed and validat... more A multi-scale combustion model involving the Kalman and Particle filters is developed and validated. The coarse-scale model consists of 1D grid which handles the mass conservation and momentum equations. In 3D this model emulates Large Eddy Simulation (LES) for turbulent variable density flow. The fine scale solution is handled using the Linear Eddy Model (LEM). The fine scale processes combine a deterministic implementation of reaction, diffusion and large scale transport with a stochastic implementation of fine scale transport.
Here, turbulent stirring is represented by random, instantaneous rearrangements of the fields of transported variables along a one dimensional line via ‘triplet maps’, which emulate the rotational effect of turbulent eddies. The algorithm has the continuity equation and the Burger’s equation on the coarse scale and the temperature equation with heat release on the fine scale.
The density computed on the fine scale has to be passed from the fine scale to the coarse scale. This density passed contributes directly to the accuracy of the solution. The behavior of finer scale data also depends on the number of points embedded in each coarse grid cell.
Therefore the values being passed should be spectrally smooth.
This work has been carried out in two parts. In the first part Kalman filter has been employed to combine these two scale solutions and in the second part Particle filter has been used to do the same. These filters have been used to remove the statistical errors in the data being passed and to make them as accurate as possible. The results convincingly establish the potential role of Kalman and Particle filters in coupling the deterministic coarse grained solutions and stochastic fine-grained solutions in reacting flow applications.

8th U.S. National Combustion Meeting, 2013

An opposed laminar flow flame formed with methane/acetylene and oxygen enriched-air was employed ... more An opposed laminar flow flame formed with methane/acetylene and oxygen enriched-air was employed to produce molybdenum oxide nanostructures directly in the gas phase. The composition of the fuel and oxidizer to form the flame was 96%CH 4 +4%C 2 H 2 and 50%O 2 /50%N 2 , respectively. Raw material was introduced into oxidizer side of the flame in the form of solid molybdenum wires with 99% purity. The high temperature and the oxygen rich chemical environment of the flame resulted in fast surface oxidation of the probes and material etching from their surfaces. Upon their interaction with the flame, the probes generated molybdenum trioxide vapors. The vapors were transported in the direction of the stagnation plane of the flame and reduced to molybdenum dioxide as they entered the low temperature fuel rich zone. The velocity gradient and thermophoretic forces in the flame affected the transport of the molybdenum dioxide precursors. These precursors in the gas phase formed nanostructures that were thermophoretically collected from the flame volume. Essential morphological variations of generated nanomaterials were observed depending on flame and probe parameters. The distance of the collection plane from the molybdenum probe also played an important role in the morphology of generated nanoforms. The molybdenum probes with diameters of 0.75 mm and 1 mm were used to achieve two distinct synthesis conditions. The variation of probe diameter affected probe temperature and resulted in different supersaturation levels of molybdenum dioxide vapors. Experiments with 1.0 mm diameter corresponded to lower supersaturation levels and resulted in the synthesis of well-defined convex polyhedron nanocrystals and nanorods. Higher material etching rates and, hence, supersaturation levels were obtained with 0.75 mm diameter probes. These conditions resulted in synthesis of mainly spherical molybdenum oxide nanomaterials agglomerated in soot-like fractal aggregates. The effect of flame parameters and material concentration on shape and structure of generated nanomaterial is also studied numerically. The underlying mechanisms governing the morphological variation of molybdenum oxide nanocrystals are analyzed using the following steps: monomers formation, nucleation, and growth. The nucleation model is based on the classical nucleation theory, and the growth model considers agglomeration and diffusion in the varying thermal environment using thermophoretic analysis. The model predictions are in good qualitative agreement with the experimental data.

Computers & Fluids, 2013

A multi-scale approach for coupling a coarse-grained (CG) deterministic solution for a reacting f... more A multi-scale approach for coupling a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution is proposed. The model includes a CG solution for the mass density and momentum and a FG solution for the temperature. A model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. A common variable is obtained from these solutions based on a CG density field defined from continuity on the coarse scales and the spatial filtering of the density derived from the state equation in the FG solution. Kalman filtering is used to combine these two solutions. The resulting CG density is both smooth and steered by heat release from the FG solution. The algorithm is demonstrated on a 1D model combining continuity and the Burgers' equation for the CG solution and the temperature equation with heat release for the FG solution. The results establish the feasibility of Kalman filtering in coupling deter-ministic CG solutions and stochastic FG solutions in reacting flow applications.

Proceedings of the Combustion Institute, 2015

A laminar counter-flow diffusion flame formed with methane/acetylene and oxygen enriched-air was ... more A laminar counter-flow diffusion flame formed with methane/acetylene and oxygen enriched-air was used for controlled synthesis of 1-D molybdenum oxide nanostructures directly in the gas phase. Raw material was introduced into the oxidizer side of the flame in the form of solid molybdenum wires with ~99% purity. Molybdenum oxide vapors formed in the gas phase were transported by the gas flow in the flame environment possessing strong thermal and chemical gradients. The generated nanostructures were collected thermophoretically from the flame volume. Essential morphological variations of generated nanomaterials were observed depending on sampling position within the flame volume and probe parameters. The mechanism behind the synthesis of the spherical and 1-D nanoforms is analyzed and modeled numerically. The nanorod growth model involves monomer transport, nucleation and growth. The monomer formation is through the oxidation and vaporization of the probe material. The nucleation model is based on the classical nucleation theory. The model predicts the trajectory and growth of the formed nuclei as they are transported in the flame volume. It is considered that the ends of the cylindrical 1-D nanorods grow by the phenomenon of rough growth while the lateral faces exhibit layered growth. The growth model also considers the contribution of the monomers diffusing on the nanoparticle surface as well as the effect of the atoms impinging directly onto the growth sites and compares their relative contributions. The model qualitatively predicts the variation of aspect ratio of the formed nanomaterials with increase of monomer concentration as observed in the experiments.

International Journal for Multiscale Computational Engineering, 2017

The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting... more The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution. The proposed method investigates the feasibility of implementing a multiscale approach for turbulent reacting flows based on large-eddy simulation (LES) coupled with a low-dimensional fine-grained stochastic solution for the subfilter scales reaction and transport. In this study, a model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. The solution for the continuity and momentum (the Burgers' equation) equations are implemented in 1D. The filtered densities obtained through the FG and the CG solutions are combined using the particle filter to obtain an updated density for the coarse solution that combines the effects of heat release (from the FG solution) and flow dynamics (from the CG solution). The results demonstrate that the particle filter may be a viable tool to couple deterministic CG solutions and stochastic FG solutions in reacting flow applications.

The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting... more The particle filter is used to couple a coarse-grained (CG) deterministic solution for a reacting flow with a fine-grained (FG) stochastic solution. The proposed method investigates the feasibility of implementing a multiscale approach for turbulent reacting flows based on largeeddy simulation (LES) coupled with a low-dimensional fine-grained stochastic solution for the subfilter scales reaction and transport. In this study, a model for the turbulent transport in the FG solution is implemented using the linear-eddy model (LEM), which combines a deterministic implementation for reaction, diffusion and large-scale transport with a stochastic implementation for fine-scale transport. The solution for the continuity and momentum (the Burgers' equation) equations are implemented in 1D. The filtered densities obtained through the FG and the CG solutions are combined using the particle filter to obtain an updated density for the coarse solution that combines the effects of heat release (from the FG solution) and flow dynamics (from the CG solution). The results demonstrate that the particle filter may be a viable tool to couple deterministic CG solutions and stochastic FG solutions in reacting flow applications.

Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2019

The injection of choked gaseous jets into the still air is investigated experimentally motivated ... more The injection of choked gaseous jets into the still air is investigated experimentally motivated by many industrial applications including flares and burners. The objective is to study the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air, seeded with water fog. The computational methods consisted of 7.7 million cells simulation using Star CCM+. The test conditions include injection angles of 0°, 15°, and 30°. The results including mean and fluctuating velocities and the flow vorticity are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

AIAA SciTech, 2020

The injection of choked gaseous jets into still air is investigated computationally and experimen... more The injection of choked gaseous jets into still air is investigated computationally and experimentally. The objective is to compare the performance of three turbulence models-Realizable k-, SST k- and Reynolds Stress Transport to resolve the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air that has been seeded with water fog. The test conditions include injection angles of 0° and 15°. The results including jet velocities and the vorticity field are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

 Study and understand the physics underlying the controlled synthesis of 1-D metal oxide nanostr... more  Study and understand the physics underlying the controlled synthesis of 1-D metal oxide nanostructures in the gas phase using the Flame Gradient Method  Numerically simulate the growth characteristics of nanorods in the flame environment  Simulate the variation in the morphology of the nanoparticles with the change in the synthesis conditions.

An Ensemble Kalman Filter (EnKF) algorithm has been developed and implemented on chaotic Lorenz 6... more An Ensemble Kalman Filter (EnKF) algorithm has been developed and implemented on chaotic Lorenz 63 model. The EnKF has been given noisy data and used to find the optimum state of the system. The EnKF output has been compared to the actual output.

A dynamic 1D mathematical model is set up to simulate the formation of vescicle traps in fast axo... more A dynamic 1D mathematical model is set up to simulate the formation of vescicle traps in fast axonal transport occuring in neurons. The model developed helps in understanding how organelle polarity mismatch leads to formation of organelle traps and how, as a consequence axonal transport is affected. The model is solved using the COMSOL multiphysics package. The results show that the organelle build up in the traps leading to jams takes a long time. The time taken to reach steady state is around 150s as compared to 30s for normal healthy axon.

To understand the effect of various engine parameters, chiefly compression ratio on the C.I. comb... more To understand the effect of various engine parameters, chiefly compression ratio on the C.I. combustion, it was decided to develop a mathematical simulation for a single cylinder diesel engine fueled with diesel. The model will predict all the working characteristics of the engine like pressure, temperature and the cylinder volume at each crank angle and thermal efficiency. A separate mathematical code has also been developed which can predict the mole fractions of twelve equilibrium species formed during combustion with any type of fuel. The program also predicts changes in Cp, Cv, enthalpy, gas constant and molecular weight of the exhaust gas.

For better efficiency of any component the wear of the component should be minimized. It is well ... more For better efficiency of any component the wear of the component should be minimized. It is well known that the presence of residual compressive stress in a component reduces wear and crack initiation. Here an attempt has been made to induce residual compressive stress in Aluminium AA6063-T6 samples through ‘Oil Jet Peening’. Friction and wear characteristics of the peened component were evaluated using cylindrical specimens in a pin-on-disc sliding apparatus under dry conditions.

"Konkan Railway is developing an Anti Collision Device using Global Positioning System. This devi... more "Konkan Railway is developing an Anti Collision Device using Global Positioning System. This device will cost Rs 350 million just for the Konkan track and Rs 16 billion for the entire country network. It is a complex system and very costly for a country like ours.
Here we attempt to develop an Anti Collision System which is cost effective, simpler and works perfectly in all conditions.
We have used pressure sensors, micro controllers, transmitters and receivers to develop our system. The entire railway network has been divided into zones and each train communicates with the controller of the zone which monitors its position and prevents accident.
Our system does not require GPS, uses indigenous technology and is very cheap.
Every collision situation has been tested by a computer software.
Signals and railway crossings can also be controlled by this system."

North Carolina State University, 2014

The past few decades have seen a great amount of interest in the field of nanotechnology. As our ... more The past few decades have seen a great amount of interest in the field of nanotechnology. As our world moves towards miniaturized devices nanotechnology is set to revolutionize the electronics, storage and sensing industry. Various methods for synthesis of different types of nanoparticles are being explored. A few of these processes that hold great promise for the future are the flame synthesis methods. These methods are highly efficient but at the same time it is difficult to control the morphology of the produced nanoparticles due to a high number of control parameters involved because of the complex flow processes. These issues demand a better understanding before these processes can be exploited to their maximum
potential.
Most numerical methods developed cater to the simulation of spherical nanoparticles.
However, it is now being increasingly understood that the shape and structure of a nanoparticle plays critical role in determining its chemical, physical and electronic properties. Therefore a high level of control on the shape of nanoparticles is highly imperative. With this purpose in mind this work proposes a novel numerical scheme to simulate the synthesis of one-dimensional nanorods and further presents mathematical simulations based on it followed by validation with experimental results.
The ability to predict the morphology of a nanoparticle formed by a synthesis process adds a distinct advantage. Therefore, intricate solutions have been found for the fluid flow and these have been coupled to each stage of nanoparticle development, namely monomer formation, nucleation, particle growth and particle transport. The numerical scheme takes into account all the details of the complex surface phenomena taking place on a nanorod. Later, factors are studied which transition the growth characteristics of a nanoparticle from one dimensional to a spherical structure, thus encompassing all the factors that influence the particle shape.
Group characteristics of nanoparticles have also been modeled by employing methods that track the growth of the entire set of nanoparticles in the flame volume. This gives a clear picture of the growth of the particle ensemble in addition to the individual particles.
This work provides a first of its kind numerical model for one-dimensional growth of nanoparticles and establishes the control parameters to achieve controlled growth of nanorods in flames

North Carolina State University, 2011

A multi-scale combustion model involving the Kalman and Particle filters is developed and validat... more A multi-scale combustion model involving the Kalman and Particle filters is developed and validated. The coarse-scale model consists of 1D grid which handles the mass conservation and momentum equations. In 3D this model emulates Large Eddy Simulation (LES) for turbulent variable density flow. The fine scale solution is handled using the Linear Eddy Model (LEM). The fine scale processes combine a deterministic implementation of reaction, diffusion and large scale transport with a stochastic implementation of fine scale transport.
Here, turbulent stirring is represented by random, instantaneous rearrangements of the fields of transported variables along a one dimensional line via ‘triplet maps’, which emulate the rotational effect of turbulent eddies. The algorithm has the continuity equation and the Burger’s equation on the coarse scale and the temperature equation with heat release on the fine scale.
The density computed on the fine scale has to be passed from the fine scale to the coarse scale. This density passed contributes directly to the accuracy of the solution. The behavior of finer scale data also depends on the number of points embedded in each coarse grid cell.
Therefore the values being passed should be spectrally smooth.
This work has been carried out in two parts. In the first part Kalman filter has been employed to combine these two scale solutions and in the second part Particle filter has been used to do the same. These filters have been used to remove the statistical errors in the data being passed and to make them as accurate as possible. The results convincingly establish the potential role of Kalman and Particle filters in coupling the deterministic coarse grained solutions and stochastic fine-grained solutions in reacting flow applications.