Svetlana Poroseva - Profile on Academia.edu (original) (raw)
Papers by Svetlana Poroseva
22nd AIAA Computational Fluid Dynamics Conference, 2015
Statistical data obtained from direct numerical simulations (DNS) are often used as reference dat... more Statistical data obtained from direct numerical simulations (DNS) are often used as reference data for validating turbulence models. Thus, accuracy of the DNS data itself is of particular importance for understanding the potential error in Reynolds-averaged Navier-Stokes (RANS) simulations. Recent studies demonstrate that when the DNS data is used to represent budget terms in the RANS equations, simulations of wall-bounded turbulent flows conducted with such equations (herein referred to as RANS-DNS simulations) produce unphysical results. The current paper analyzes the contribution that convergence of DNS statistics makes to this discrepancy. The Reynolds stresses and budget terms in the RANS equations are collected in a fully developed channel flow (
Monte Carlo optimization of a matrix-based power-grid islanding algorithm
Spectral matrix methods are widely used for intelligent intentional islanding of power grids, the... more Spectral matrix methods are widely used for intelligent intentional islanding of power grids, the purposeful partitioning of a utility system to limit cascading disturbances. However, these methods may produce unbalanced islands of generators and loads when applied recursively. While some of the resulting islands have surplus generating capacity, others are deficient. We here implement a Monte Carlo simulated-annealing optimization procedure
Network-theoretical approach to partitioning of real power grids
Modern societies depend critically on their electrical power grids. It is, therefore, essential t... more Modern societies depend critically on their electrical power grids. It is, therefore, essential to understand the grid's large-scale behavior in order to improve its resilience against catastrophic damage. A key factor determining the grid's large-scale behavior is its topology. In particular, an important question is whether a grid topology can be efficiently partitioned into independent communities (``islands'') of densely connected
Optimization of a power-grid islanding algorithm using Monte Carlo simulations
The purposeful partitioning of a utility system to limit the cascading disturbances is called int... more The purposeful partitioning of a utility system to limit the cascading disturbances is called intelligent intentional islanding. Spectral matrix methods for intelligent intentional islanding of power grids may produce unbalanced clusters of generators and loads when applied recursively. While some of the resulting clusters have surplus generating capacity, others are deficient. To limit cascading power failures by isolating highly connected
2008 IEEE/PES Transmission and Distribution Conference and Exposition, 2008
Survivability, or the ability to provide power to consumers/loads in spite of multiple simultaneo... more Survivability, or the ability to provide power to consumers/loads in spite of multiple simultaneous faults caused by natural or hostile disruptions, is a desirable feature of any power system. Topology (or design) is a key factor determining survivability of the power system. In our study, we develop mathematical and numerical tools to analyze the topological survivability of utility power systems. A new web topology of enhanced survivability is suggested.
IEEE Electric Ship Technologies Symposium, 2005., 2005
Future naval platforms will feature an Integrated Power System (IPS) that provides power for all ... more Future naval platforms will feature an Integrated Power System (IPS) that provides power for all ship systems, including propulsion, combat systems, ship service loads and, ultimately, weapons. It is naturally a requirement that the power system be highly reliable and one of the benefits of the all-electric concept is that reliability in general and, specifically, survivability in battle are enhanced by the ability to reassign power components and network paths to dynamically reconfigure the system in response to events. Much research is being directed at the question of how best to reconfigure a system when portions are damaged: this includes choosing the optimal reconfiguration possible in the system, evaluating the effect of transients introduced by the damage and the switching in and out of parts of the network, etc. Little attention has been focused, however, on the how much reconfiguration is possible in a given network, particularly in the event of multiple faults; after all, if there is no alternative path available between source and load, there can be no reconfiguration. Alternatively, little attention has been given to the question of how to design the network so as to give maximum survivability. These questions are vital, regardless of what reconfiguration strategy is chosen.
52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 2011
Survivability, or the ability to deliver service in spite of multiple simultaneous faults caused ... more Survivability, or the ability to deliver service in spite of multiple simultaneous faults caused by natural or hostile disruptions, is a desirable feature of any complex system. Our study is relevant to systems with sources (elements generating a quality of interest) and sinks (elements consuming this quantity). A key factor for such a system to survive is its topology, that is, the number of sources and sinks and their connections with one another. Previously, we developed a methodology for conducting the analysis of the system survivability due to its topology. However, the application of the analysis to real-life systems such as, for example, power systems, is a computational challenge. System topologies usually contain thousands of elements. The problem can be solved in principle by decomposing a topology with multiple sinks and multiple sources into a few sub-topologies with multiple sources and a single sink. An efficient computational procedure for the survivability analysis of a single-sink topology has already been developed in our previous studies. Two other steps that have yet to be developed are i) automatical transformation of a system diagram into a form suitable for the computational analysis and ii) automatical decomposition of a system with multiple sources and sinks into simpler sub-systems. The current paper reports on software development for converting a standard power system diagram into a structured adjacency matrix or list.
Structural analysis for assessment of monitoring possibilities: Application to simple power system topologies
2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century, 2008
Abstract Any power system, either an integrated power system in an all-electric ship or a utility... more Abstract Any power system, either an integrated power system in an all-electric ship or a utility power system, needs to be highly reliable. Reliability of a complex system strongly depends on the possibility of detecting faults and isolating them from each other, ie, on the monitoring potential of the system. The area of power system engineering that is concerned with the fault detection and isolation is called protection. As power systems becoming more and more complex, current standards for their protection should be adjusted accordingly ...
PANS simulations of the turbulent flow over a surface mounted cube
ABSTRACT
Physics of pressure-strain correlation in rapidly distorted turbulence
Rapid distortion calculations of initially anisotropic turbulence are performed to better underst... more Rapid distortion calculations of initially anisotropic turbulence are performed to better understand the physics of pressure-strain correlation. In the talk several interesting aspects of the correlation behavior inferred from the simulations will be presented. Although these features of the correlation appear self-evident, most of the current models violate them. The violations are significant as they appear to directly lead to unrealizable and inconsistent model behavior.
In the paper, a new technique to quantify the accuracy of models for weather prediction in foreca... more In the paper, a new technique to quantify the accuracy of models for weather prediction in forecasting tracks of tropical cyclones using the available best track database is presented. Also a new approach to quantify and improve the accuracy of tropical cyclone track forecasts where no best track positions are available is suggested. Both techniques rely on the mathematical tools of evidence theory, which are customized here for application to total uncertainty in track forecasts.
Laminar solution in an oscillating channel flow and its implication to the turbulent case
ABSTRACT
Simulation of a turbulent rotated pipe flow with the structure - based model
ABSTRACT
Mean rotation induces dynamical effects on turbulence that enter the transport equations through ... more Mean rotation induces dynamical effects on turbulence that enter the transport equations through the non-local pressure-strain-rate correlation. It was shown in and that, to describe this effect accurately using one-point turbulence statistics, a turbulence model should include the transport equations not only for Reynolds stresses, but also for additional tensors providing information on turbulence structure missing from the Reynolds stresses. Two second-rank tensors, dimensionality D ij and circulicity F ij , as well as the third-rank stropholysis tensor Q * ijk along with the Reynolds stresses R ij , form a minimal set of independent tensors necessary for a one-point closure in the case of inhomogeneous turbulence. Relying on these ideas, the structure-based model has been developed in and tested successfully for a wide range of deformations of homogeneous turbulence as well as for some simple wall-bounded flows .
On Further Enhancement of CFD Predictive Algorithms Based on Evidence Theory
The Dempster-Shafer theory of evidence provides two basic tools -- i) belief functions that repre... more The Dempster-Shafer theory of evidence provides two basic tools -- i) belief functions that represent the degree of belief (confidence) in a given proposition on the basis of given evidence, and ii) Dempster's rule for combining the belief functions generated by different sources in relation to the same proposition. Previously, we have shown that these tools can be used effectively in application to various CFD problems (subsonic flow around the RAE 2822 airfoil and hurricane/typhoon track forecasts). The current study focuses on further enhancement of the predictive algorithms employing Dempster's rule. Specifically, we analyze one of the requirements of Dempster's rule that belief functions corresponding to different sources should be constructed using independent evidence. In CFD problems, evidence is experimental/observational data, which can be quite limited in number and barely sufficient to construct a single belief function. Application of Dempster's rule requires a minimum of two belief functions. We examine the origin of the requirement that independent data be used to construct belief functions and consider a strategy to overcome this constraint and its implications.
In the paper, a new technique to quantify the accuracy of models for weather prediction in foreca... more In the paper, a new technique to quantify the accuracy of models for weather prediction in forecasting tracks of tropical cyclones using the available best track database is presented. Also a new approach to quantify and improve the accuracy of tropical cyclone track forecasts where no best track positions are available is suggested. Both techniques rely on the mathematical tools of evidence theory, which are customized here for application to total uncertainty in track forecasts.
The contribution of the "rapid" part of the pressure diffusion to the turbulent kinetic energy ba... more The contribution of the "rapid" part of the pressure diffusion to the turbulent kinetic energy balance is analyzed, and a new model to describe its effect is suggested. A new transport equation for the turbulent kinetic energy is derived. The new k-equation does not require any modification in the standard ε-equation. A new k-ε model, which includes the new k-equation and the standard ε-equation, is validated in four separated flows: a planar diffuser, over a backstep, in a channel with wavy walls, and in an axisymmetric combustion chamber. It is shown that a new model reproduces the mean velocity, shear stress, and turbulent kinetic energy profiles and the skin friction coefficient in very good agreement with experimental data
Uncertainty Quantification in Hurricane Path Forecasts using Evidence Theory
ABSTRACT
22nd AIAA Computational Fluid Dynamics Conference, 2015
Statistical data obtained from direct numerical simulations (DNS) are often used as reference dat... more Statistical data obtained from direct numerical simulations (DNS) are often used as reference data for validating turbulence models. Thus, accuracy of the DNS data itself is of particular importance for understanding the potential error in Reynolds-averaged Navier-Stokes (RANS) simulations. Recent studies demonstrate that when the DNS data is used to represent budget terms in the RANS equations, simulations of wall-bounded turbulent flows conducted with such equations (herein referred to as RANS-DNS simulations) produce unphysical results. The current paper analyzes the contribution that convergence of DNS statistics makes to this discrepancy. The Reynolds stresses and budget terms in the RANS equations are collected in a fully developed channel flow (
Monte Carlo optimization of a matrix-based power-grid islanding algorithm
Spectral matrix methods are widely used for intelligent intentional islanding of power grids, the... more Spectral matrix methods are widely used for intelligent intentional islanding of power grids, the purposeful partitioning of a utility system to limit cascading disturbances. However, these methods may produce unbalanced islands of generators and loads when applied recursively. While some of the resulting islands have surplus generating capacity, others are deficient. We here implement a Monte Carlo simulated-annealing optimization procedure
Network-theoretical approach to partitioning of real power grids
Modern societies depend critically on their electrical power grids. It is, therefore, essential t... more Modern societies depend critically on their electrical power grids. It is, therefore, essential to understand the grid's large-scale behavior in order to improve its resilience against catastrophic damage. A key factor determining the grid's large-scale behavior is its topology. In particular, an important question is whether a grid topology can be efficiently partitioned into independent communities (``islands'') of densely connected
Optimization of a power-grid islanding algorithm using Monte Carlo simulations
The purposeful partitioning of a utility system to limit the cascading disturbances is called int... more The purposeful partitioning of a utility system to limit the cascading disturbances is called intelligent intentional islanding. Spectral matrix methods for intelligent intentional islanding of power grids may produce unbalanced clusters of generators and loads when applied recursively. While some of the resulting clusters have surplus generating capacity, others are deficient. To limit cascading power failures by isolating highly connected
2008 IEEE/PES Transmission and Distribution Conference and Exposition, 2008
Survivability, or the ability to provide power to consumers/loads in spite of multiple simultaneo... more Survivability, or the ability to provide power to consumers/loads in spite of multiple simultaneous faults caused by natural or hostile disruptions, is a desirable feature of any power system. Topology (or design) is a key factor determining survivability of the power system. In our study, we develop mathematical and numerical tools to analyze the topological survivability of utility power systems. A new web topology of enhanced survivability is suggested.
IEEE Electric Ship Technologies Symposium, 2005., 2005
Future naval platforms will feature an Integrated Power System (IPS) that provides power for all ... more Future naval platforms will feature an Integrated Power System (IPS) that provides power for all ship systems, including propulsion, combat systems, ship service loads and, ultimately, weapons. It is naturally a requirement that the power system be highly reliable and one of the benefits of the all-electric concept is that reliability in general and, specifically, survivability in battle are enhanced by the ability to reassign power components and network paths to dynamically reconfigure the system in response to events. Much research is being directed at the question of how best to reconfigure a system when portions are damaged: this includes choosing the optimal reconfiguration possible in the system, evaluating the effect of transients introduced by the damage and the switching in and out of parts of the network, etc. Little attention has been focused, however, on the how much reconfiguration is possible in a given network, particularly in the event of multiple faults; after all, if there is no alternative path available between source and load, there can be no reconfiguration. Alternatively, little attention has been given to the question of how to design the network so as to give maximum survivability. These questions are vital, regardless of what reconfiguration strategy is chosen.
52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 2011
Survivability, or the ability to deliver service in spite of multiple simultaneous faults caused ... more Survivability, or the ability to deliver service in spite of multiple simultaneous faults caused by natural or hostile disruptions, is a desirable feature of any complex system. Our study is relevant to systems with sources (elements generating a quality of interest) and sinks (elements consuming this quantity). A key factor for such a system to survive is its topology, that is, the number of sources and sinks and their connections with one another. Previously, we developed a methodology for conducting the analysis of the system survivability due to its topology. However, the application of the analysis to real-life systems such as, for example, power systems, is a computational challenge. System topologies usually contain thousands of elements. The problem can be solved in principle by decomposing a topology with multiple sinks and multiple sources into a few sub-topologies with multiple sources and a single sink. An efficient computational procedure for the survivability analysis of a single-sink topology has already been developed in our previous studies. Two other steps that have yet to be developed are i) automatical transformation of a system diagram into a form suitable for the computational analysis and ii) automatical decomposition of a system with multiple sources and sinks into simpler sub-systems. The current paper reports on software development for converting a standard power system diagram into a structured adjacency matrix or list.
Structural analysis for assessment of monitoring possibilities: Application to simple power system topologies
2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century, 2008
Abstract Any power system, either an integrated power system in an all-electric ship or a utility... more Abstract Any power system, either an integrated power system in an all-electric ship or a utility power system, needs to be highly reliable. Reliability of a complex system strongly depends on the possibility of detecting faults and isolating them from each other, ie, on the monitoring potential of the system. The area of power system engineering that is concerned with the fault detection and isolation is called protection. As power systems becoming more and more complex, current standards for their protection should be adjusted accordingly ...
PANS simulations of the turbulent flow over a surface mounted cube
ABSTRACT
Physics of pressure-strain correlation in rapidly distorted turbulence
Rapid distortion calculations of initially anisotropic turbulence are performed to better underst... more Rapid distortion calculations of initially anisotropic turbulence are performed to better understand the physics of pressure-strain correlation. In the talk several interesting aspects of the correlation behavior inferred from the simulations will be presented. Although these features of the correlation appear self-evident, most of the current models violate them. The violations are significant as they appear to directly lead to unrealizable and inconsistent model behavior.
In the paper, a new technique to quantify the accuracy of models for weather prediction in foreca... more In the paper, a new technique to quantify the accuracy of models for weather prediction in forecasting tracks of tropical cyclones using the available best track database is presented. Also a new approach to quantify and improve the accuracy of tropical cyclone track forecasts where no best track positions are available is suggested. Both techniques rely on the mathematical tools of evidence theory, which are customized here for application to total uncertainty in track forecasts.
Laminar solution in an oscillating channel flow and its implication to the turbulent case
ABSTRACT
Simulation of a turbulent rotated pipe flow with the structure - based model
ABSTRACT
Mean rotation induces dynamical effects on turbulence that enter the transport equations through ... more Mean rotation induces dynamical effects on turbulence that enter the transport equations through the non-local pressure-strain-rate correlation. It was shown in and that, to describe this effect accurately using one-point turbulence statistics, a turbulence model should include the transport equations not only for Reynolds stresses, but also for additional tensors providing information on turbulence structure missing from the Reynolds stresses. Two second-rank tensors, dimensionality D ij and circulicity F ij , as well as the third-rank stropholysis tensor Q * ijk along with the Reynolds stresses R ij , form a minimal set of independent tensors necessary for a one-point closure in the case of inhomogeneous turbulence. Relying on these ideas, the structure-based model has been developed in and tested successfully for a wide range of deformations of homogeneous turbulence as well as for some simple wall-bounded flows .
On Further Enhancement of CFD Predictive Algorithms Based on Evidence Theory
The Dempster-Shafer theory of evidence provides two basic tools -- i) belief functions that repre... more The Dempster-Shafer theory of evidence provides two basic tools -- i) belief functions that represent the degree of belief (confidence) in a given proposition on the basis of given evidence, and ii) Dempster's rule for combining the belief functions generated by different sources in relation to the same proposition. Previously, we have shown that these tools can be used effectively in application to various CFD problems (subsonic flow around the RAE 2822 airfoil and hurricane/typhoon track forecasts). The current study focuses on further enhancement of the predictive algorithms employing Dempster's rule. Specifically, we analyze one of the requirements of Dempster's rule that belief functions corresponding to different sources should be constructed using independent evidence. In CFD problems, evidence is experimental/observational data, which can be quite limited in number and barely sufficient to construct a single belief function. Application of Dempster's rule requires a minimum of two belief functions. We examine the origin of the requirement that independent data be used to construct belief functions and consider a strategy to overcome this constraint and its implications.
In the paper, a new technique to quantify the accuracy of models for weather prediction in foreca... more In the paper, a new technique to quantify the accuracy of models for weather prediction in forecasting tracks of tropical cyclones using the available best track database is presented. Also a new approach to quantify and improve the accuracy of tropical cyclone track forecasts where no best track positions are available is suggested. Both techniques rely on the mathematical tools of evidence theory, which are customized here for application to total uncertainty in track forecasts.
The contribution of the "rapid" part of the pressure diffusion to the turbulent kinetic energy ba... more The contribution of the "rapid" part of the pressure diffusion to the turbulent kinetic energy balance is analyzed, and a new model to describe its effect is suggested. A new transport equation for the turbulent kinetic energy is derived. The new k-equation does not require any modification in the standard ε-equation. A new k-ε model, which includes the new k-equation and the standard ε-equation, is validated in four separated flows: a planar diffuser, over a backstep, in a channel with wavy walls, and in an axisymmetric combustion chamber. It is shown that a new model reproduces the mean velocity, shear stress, and turbulent kinetic energy profiles and the skin friction coefficient in very good agreement with experimental data
Uncertainty Quantification in Hurricane Path Forecasts using Evidence Theory
ABSTRACT