We consider the effect of acoustical radiation upon the particle size distribution in pharmaceuti... more We consider the effect of acoustical radiation upon the particle size distribution in pharmaceutical sprays. A mixed particle hydrodynamic-Eulerian technique is used to model the propagation of acoustic waves through the spray and the effect of the acoustic radiation upon spray droplets. A model for droplet breakdown based upon normal mode oscillations is employed to capture acoustically induced modifications of
Many proto-planetary nebulae (PPN) appear as narrow collimated structures sometimes showing multi... more Many proto-planetary nebulae (PPN) appear as narrow collimated structures sometimes showing multiple, roughly aligned lobes. In addition, many PPN flows have been shown to have short acceleration times. In this paper we explore whether jet or ``bullet'' (a massive clump) models fit the observations of individual collimated lobes adequately by comparing simulations of both radiatively cooled (stable) jets and bullets.
We present an exact solution for a moving wall in the presence of an unstable density stratificat... more We present an exact solution for a moving wall in the presence of an unstable density stratification. We discuss the linear stability of the system through the analysis of the associated Orr-Somerfeld type eigenvalue problem. Time permitting, full simulations of the nonlinear system based on pseudospectral projection methods will be presented.
Determine whether quantitative geometric measures and a computational fluid dynamic (CFD) model d... more Determine whether quantitative geometric measures and a computational fluid dynamic (CFD) model derived from medical imaging of children with subglottic stenosis (SGS) can be effective diagnostic and treatment planning tools. Retrospective chart and imaging review in a tertiary care hospital. Computed tomography scans (n = 17) of children with SGS were analyzed by geometric and CFD methods. Polysomnograms (n = 15) were also analyzed. Radiographic data were age/weight flow normalized and were compared to an atlas created from radiographically normal airways. Five geometric, seven CFD, and five polysomnography measures were analyzed. Statistical analysis utilized a two-sample t test with Bonferroni correction and area under the curve analysis. Two geometric indices (the ratio of the subglottic to midtracheal airway, the percent relative reduction of the subglottic airway) and one CFD measure (the percent relative reduction of the hydraulic diameter of the subglottic airway) were significant for determining which children with SGS received surgical intervention. Optimal cutoffs for these values were determined. Polysomnography, the respiratory effort-related arousals index, was significant only prior to Bonferroni correction for determining which children received surgical intervention. Geometric and CFD variables were sensitive at determining which patients with SGS received surgical intervention. Discrete quantitative assessment of the pediatric airway was performed, yielding preliminary data regarding possible objective thresholds for surgical versus nonsurgical treatment of disease. This study is limited by its small, retrospective, single-institution nature. Further studies to validate these findings and possibly optimize treatment threshold recommendations are warranted. 4 Laryngoscope, 2015.
We develop a hierarchy of approximations to the master equation for systems that exhibit translat... more We develop a hierarchy of approximations to the master equation for systems that exhibit translational invariance and finite-range spatial correlation. Each approximation within the hierarchy is a set of ordinary differential equations that considers spatial correlations of varying lattice distance; the assumption is that the full system will have finite spatial correlations and thus the behavior of the models within the hierarchy will approach that of the full system. We provide evidence of this convergence in the context of one- and two-dimensional numerical examples. Lower levels within the hierarchy that consider shorter spatial correlations are shown to be up to three orders of magnitude faster than traditional kinetic Monte Carlo methods (KMC) for one-dimensional systems, while predicting similar system dynamics and steady states as KMC methods. We then test the hierarchy on a two-dimensional model for the oxidation of CO on RuO2(110), showing that low-order truncations of the...
36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2000
Perot's turbulent potential model introduces a Helmholtz representation of the diver... more Perot's turbulent potential model introduces a Helmholtz representation of the divergence of the Reynolds stress tensor into a scalar and a vector potential. Transport equations for the potentials are solved in order to compute Reynolds stresses. The model constants for these transport equations had previously been determined by analogy to other turbulence models and considerations of certain simplified turbulent flows. The applicability of these constants to the complex turbulent flows encountered in turbomachinery is undetermined. In this work a large eddy ...
Lecture Notes in Computational Science and Engineering, 2005
Adaptive Mesh Refinement methods combined with modern shock-capturing techniques hold great promi... more Adaptive Mesh Refinement methods combined with modern shock-capturing techniques hold great promise for the simulation of many astrophysical fluid dynamics environments. This is particularly true of problems involving strong shocks followed by efficient cooling via radiative losses. The high degrees of compression achieved in such circumstances require high resolutions that can tax the computational resources of many research groups. The need to accurately compute various micro-physical processes (non-equilibrium ionization, ...
Many proto-planetary nebulae (PPNs) appear as narrow collimated structures sometimes showing mult... more Many proto-planetary nebulae (PPNs) appear as narrow collimated structures sometimes showing multiple, roughly aligned lobes. In addition, many PPN flows have been shown to have short acceleration times. In this paper we explore whether jet or ``bullet'' (a massive clump) models fit the observations of individual collimated lobes adequately by comparing simulations of both radiatively cooled (stable) jets and bullets.
Studies in Mechanobiology, Tissue Engineering and Biomaterials, 2010
Cellular blebbing occurs when detachment of the underlying cytoskeleton from a portion of the pla... more Cellular blebbing occurs when detachment of the underlying cytoskeleton from a portion of the plasma membrane leads to the formation of protrusions under the influence of cytosol pressure. Blebbing is associated with cellular apoptosis and has been linked to diseased states such as cancer. Multiple phenomena at disparate scales occur during blebbing. At the molecular scale there are biochemical reactions governing actin polymerization, cross-linkage, and formation of membrane adhesion complexes. At the cellular level, forces on ...
... Solving an AdvectionDiffusion Equation by a Finite Element Method ... 1 Numerical Approximati... more ... Solving an AdvectionDiffusion Equation by a Finite Element Method ... 1 Numerical Approximation of Model Partial Differential Equations Project Summary Levelofdifficulty: 1 ... Linear differentialequations; numerical integration methods; finite difference schemes: Euler schemes ...
Many astrophysical flows occur in inhomogeneous media. We briefly discuss some general properties... more Many astrophysical flows occur in inhomogeneous media. We briefly discuss some general properties of the adiabatic and radiative inhomogeneous systems and discuss the relevance of those properties to the planetary nebulae systems. We then focus on radiative hypersonic bullets and the applicability of this model to planetary and protoplanetary systems such as CRL 618, NGC 6543, Hen 3-1475.
We consider the effect of acoustical radiation upon the particle size distribution in pharmaceuti... more We consider the effect of acoustical radiation upon the particle size distribution in pharmaceutical sprays. A mixed particle hydrodynamic-Eulerian technique is used to model the propagation of acoustic waves through the spray and the effect of the acoustic radiation upon spray droplets. A model for droplet breakdown based upon normal mode oscillations is employed to capture acoustically induced modifications of
Many proto-planetary nebulae (PPN) appear as narrow collimated structures sometimes showing multi... more Many proto-planetary nebulae (PPN) appear as narrow collimated structures sometimes showing multiple, roughly aligned lobes. In addition, many PPN flows have been shown to have short acceleration times. In this paper we explore whether jet or ``bullet'' (a massive clump) models fit the observations of individual collimated lobes adequately by comparing simulations of both radiatively cooled (stable) jets and bullets.
We present an exact solution for a moving wall in the presence of an unstable density stratificat... more We present an exact solution for a moving wall in the presence of an unstable density stratification. We discuss the linear stability of the system through the analysis of the associated Orr-Somerfeld type eigenvalue problem. Time permitting, full simulations of the nonlinear system based on pseudospectral projection methods will be presented.
Determine whether quantitative geometric measures and a computational fluid dynamic (CFD) model d... more Determine whether quantitative geometric measures and a computational fluid dynamic (CFD) model derived from medical imaging of children with subglottic stenosis (SGS) can be effective diagnostic and treatment planning tools. Retrospective chart and imaging review in a tertiary care hospital. Computed tomography scans (n = 17) of children with SGS were analyzed by geometric and CFD methods. Polysomnograms (n = 15) were also analyzed. Radiographic data were age/weight flow normalized and were compared to an atlas created from radiographically normal airways. Five geometric, seven CFD, and five polysomnography measures were analyzed. Statistical analysis utilized a two-sample t test with Bonferroni correction and area under the curve analysis. Two geometric indices (the ratio of the subglottic to midtracheal airway, the percent relative reduction of the subglottic airway) and one CFD measure (the percent relative reduction of the hydraulic diameter of the subglottic airway) were significant for determining which children with SGS received surgical intervention. Optimal cutoffs for these values were determined. Polysomnography, the respiratory effort-related arousals index, was significant only prior to Bonferroni correction for determining which children received surgical intervention. Geometric and CFD variables were sensitive at determining which patients with SGS received surgical intervention. Discrete quantitative assessment of the pediatric airway was performed, yielding preliminary data regarding possible objective thresholds for surgical versus nonsurgical treatment of disease. This study is limited by its small, retrospective, single-institution nature. Further studies to validate these findings and possibly optimize treatment threshold recommendations are warranted. 4 Laryngoscope, 2015.
We develop a hierarchy of approximations to the master equation for systems that exhibit translat... more We develop a hierarchy of approximations to the master equation for systems that exhibit translational invariance and finite-range spatial correlation. Each approximation within the hierarchy is a set of ordinary differential equations that considers spatial correlations of varying lattice distance; the assumption is that the full system will have finite spatial correlations and thus the behavior of the models within the hierarchy will approach that of the full system. We provide evidence of this convergence in the context of one- and two-dimensional numerical examples. Lower levels within the hierarchy that consider shorter spatial correlations are shown to be up to three orders of magnitude faster than traditional kinetic Monte Carlo methods (KMC) for one-dimensional systems, while predicting similar system dynamics and steady states as KMC methods. We then test the hierarchy on a two-dimensional model for the oxidation of CO on RuO2(110), showing that low-order truncations of the...
36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2000
Perot's turbulent potential model introduces a Helmholtz representation of the diver... more Perot's turbulent potential model introduces a Helmholtz representation of the divergence of the Reynolds stress tensor into a scalar and a vector potential. Transport equations for the potentials are solved in order to compute Reynolds stresses. The model constants for these transport equations had previously been determined by analogy to other turbulence models and considerations of certain simplified turbulent flows. The applicability of these constants to the complex turbulent flows encountered in turbomachinery is undetermined. In this work a large eddy ...
Lecture Notes in Computational Science and Engineering, 2005
Adaptive Mesh Refinement methods combined with modern shock-capturing techniques hold great promi... more Adaptive Mesh Refinement methods combined with modern shock-capturing techniques hold great promise for the simulation of many astrophysical fluid dynamics environments. This is particularly true of problems involving strong shocks followed by efficient cooling via radiative losses. The high degrees of compression achieved in such circumstances require high resolutions that can tax the computational resources of many research groups. The need to accurately compute various micro-physical processes (non-equilibrium ionization, ...
Many proto-planetary nebulae (PPNs) appear as narrow collimated structures sometimes showing mult... more Many proto-planetary nebulae (PPNs) appear as narrow collimated structures sometimes showing multiple, roughly aligned lobes. In addition, many PPN flows have been shown to have short acceleration times. In this paper we explore whether jet or ``bullet'' (a massive clump) models fit the observations of individual collimated lobes adequately by comparing simulations of both radiatively cooled (stable) jets and bullets.
Studies in Mechanobiology, Tissue Engineering and Biomaterials, 2010
Cellular blebbing occurs when detachment of the underlying cytoskeleton from a portion of the pla... more Cellular blebbing occurs when detachment of the underlying cytoskeleton from a portion of the plasma membrane leads to the formation of protrusions under the influence of cytosol pressure. Blebbing is associated with cellular apoptosis and has been linked to diseased states such as cancer. Multiple phenomena at disparate scales occur during blebbing. At the molecular scale there are biochemical reactions governing actin polymerization, cross-linkage, and formation of membrane adhesion complexes. At the cellular level, forces on ...
... Solving an AdvectionDiffusion Equation by a Finite Element Method ... 1 Numerical Approximati... more ... Solving an AdvectionDiffusion Equation by a Finite Element Method ... 1 Numerical Approximation of Model Partial Differential Equations Project Summary Levelofdifficulty: 1 ... Linear differentialequations; numerical integration methods; finite difference schemes: Euler schemes ...
Many astrophysical flows occur in inhomogeneous media. We briefly discuss some general properties... more Many astrophysical flows occur in inhomogeneous media. We briefly discuss some general properties of the adiabatic and radiative inhomogeneous systems and discuss the relevance of those properties to the planetary nebulae systems. We then focus on radiative hypersonic bullets and the applicability of this model to planetary and protoplanetary systems such as CRL 618, NGC 6543, Hen 3-1475.
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Papers by Sorin Mitran