satish kumar - Academia.edu (original) (raw)

Papers by satish kumar

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.

2009 American Control Conference, 2009

Polymer, 2005

Polymer solution above a critical concentration is generally required for making a uniform diamet... more Polymer solution above a critical concentration is generally required for making a uniform diameter nano fiber by electrospinning. Below this critical concentration, nanofibers are accompanied with bead formation and, therefore, this concentration region has not received much attention. A systematic investigation reveals that unique particle shapes can be obtained by electroprocessing within this lower concentration range. Several micrometer diameter poly(methyl methacrylate) PMMA cups with wall thickness in the 200-800 nm range and 50-300 nm size pores have been obtained by electroprocessing in high dielectric constant solvents. q

Physics of Fluids, 1999

When a container of liquid is subject to vertical sinusoidal oscillation, the free surface become... more When a container of liquid is subject to vertical sinusoidal oscillation, the free surface becomes unstable at a critical driving acceleration and gives rise to standing waves. Here, we consider containers of finite depth, neglect the influence of lateral boundaries, and perform a linear stability analysis for viscoelastic liquids. Floquet theory is applied to transform the linearized governing equations into a recursion relation for the temporal modes of the free surface deformation. The recursion relation is studied both numerically and analytically for the case where the polymer stresses are described by a single-mode Maxwell model. When surface tension forces are sufficiently strong relative to elastic forces, the standing waves respond subharmonically to the driving frequency. When elastic forces become sufficiently strong relative to surface tension forces, the standing waves can respond harmonically if the product of the driving frequency and the liquid relaxation time is not too large or too small. Dramatic changes are seen in the behavior of the neutral stability curves, dispersion relations, and instability thresholds. The results of this study indicate that the behavior of parametrically driven surface waves is very sensitive to the liquid relaxation time, and suggest that such waves may serve as a useful tool for the measurement of rheological properties.