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Michael Zingale - One of the best experts on this subject based on the ideXlab platform.
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MAESTRO: AN ADAPTIVE LOW MACH NUMBER HYDRODYNAMICS ALGORITHM FOR STELLAR FLOWS
The Astrophysical Journal Supplement Series, 2010Co-Authors: Andrew Nonaka, Michael J. Lijewski, John B. Bell, Ann S. Almgren, C. M. Malone, Michael ZingaleAbstract:Many astrophysical phenomena are highly subsonic, requiring specialized numerical methods suitable for long-time integration. In a series of earlier papers we described the development of MAESTRO, a low Mach number stellar hydrodynamics code that can be used to simulate long-time, low-speed flows that would be prohibitively expensive to model using traditional compressible codes. MAESTRO is based on an Equation Set derived using low Mach number asymptotics; this Equation Set does not explicitly track acoustic waves and thus allows a significant increase in the time step. MAESTRO is suitable for two- and three-dimensional local atmospheric flows as well as three-dimensional full-star flows. Here, we continue the development of MAESTRO by incorporating adaptive mesh refinement (AMR). The primary difference between MAESTRO and other structured grid AMR approaches for incompressible and low Mach number flows is the presence of the time-dependent base state, whose evolution is coupled to the evolution of the full solution. We also describe how to incorporate the expansion of the base state for full-star flows, which involves a novel mapping technique between the one-dimensional base state and the Cartesian grid, as well as a number of overall improvements to the algorithm. We examine the efficiency and accuracy of our adaptive code, and demonstrate that it is suitable for further study of our initial scientific application, the convective phase of Type Ia supernovae.
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Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:The convective period leading up to a Type Ia supernova (SNIa) explosion is characterized by very low Mach number flows, requiringhydrodynamical methods well-suited to long-time integration. We continuethe development of the low Mach number Equation Set for stellar scaleflows by incorporating the effects of heat release due to externalsources. Low Mach number hydrodynamics Equations with a time-dependentbackground state are derived, and a numerical method based on theapproximate projection formalism is presented. We demonstrate throughvalidation with a fully compressible hydrodynamics code that this lowMach number model accurately captures the expansion of the stellaratmosphere as well as the local dynamics due to external heat sources.This algorithm provides the basis for an efficient simulation tool forstudying the ignition of SNe Ia.
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Low mach number modeling of type Ia supernovae. I. Hydrodynamics
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and a savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional anelastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
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Low Mach Number Modeling of Type Ia Supernovae
The Astrophysical Journal, 2005Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
Sheng Li - One of the best experts on this subject based on the ideXlab platform.
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A Computational Study on the Mechanical Power Loss of a Spur Gear Pair Under the Thermal Tribo-Dynamic Condition
Volume 10: ASME 2015 Power Transmission and Gearing Conference; 23rd Reliability Stress Analysis and Failure Prevention Conference, 2015Co-Authors: Sheng LiAbstract:This study proposes a formulation for the description of the gear mesh mechanical power loss under the thermal tribodynamic condition. A six degree-of-freedom motion Equation Set that models the vibratory motions of a general spur gear pair is coupled with the governing Equations for the description of the gear thermal mixed elastohydrodynamic lubrication to include the interactions between the gear dynamics and gear tribology disciplines in the modeling of the gear mesh mechanical power loss. The important role of the gear thermal tribo-dynamics in power loss is demonstrated by comparing the predictions of the proposed model to those under the thermal quasi-static condition, and the iso-thermal tribo-dynamic condition, respectively.Copyright © 2015 by ASME
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A thermal tribo-dynamic mechanical power loss model for spur gear Pairs
Tribology International, 2015Co-Authors: Sheng LiAbstract:Abstract This study proposes a formulation for the description of the gear mesh mechanical power loss under the thermal tribo-dynamic condition. A six degree-of-freedom motion Equation Set and the thermal mixed elastohydrodynamic lubrication governing Equations are coupled to model the mechanical power loss under the condition where the gear dynamics and tribology disciplines interact. The important role of the gear thermal tribo-dynamics in power loss is demonstrated by comparing the predictions of the proposed model to those under the thermal quasi-static condition, and those under the iso-thermal tribo-dynamic condition. Considering an example spur gear pair, the impacts of the lubricant inlet temperature, input torque, and surface roughness on gear mesh mechanical power loss under the thermal tribo-dynamic condition are also investigated.
Ann S. Almgren - One of the best experts on this subject based on the ideXlab platform.
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MAESTRO: AN ADAPTIVE LOW MACH NUMBER HYDRODYNAMICS ALGORITHM FOR STELLAR FLOWS
The Astrophysical Journal Supplement Series, 2010Co-Authors: Andrew Nonaka, Michael J. Lijewski, John B. Bell, Ann S. Almgren, C. M. Malone, Michael ZingaleAbstract:Many astrophysical phenomena are highly subsonic, requiring specialized numerical methods suitable for long-time integration. In a series of earlier papers we described the development of MAESTRO, a low Mach number stellar hydrodynamics code that can be used to simulate long-time, low-speed flows that would be prohibitively expensive to model using traditional compressible codes. MAESTRO is based on an Equation Set derived using low Mach number asymptotics; this Equation Set does not explicitly track acoustic waves and thus allows a significant increase in the time step. MAESTRO is suitable for two- and three-dimensional local atmospheric flows as well as three-dimensional full-star flows. Here, we continue the development of MAESTRO by incorporating adaptive mesh refinement (AMR). The primary difference between MAESTRO and other structured grid AMR approaches for incompressible and low Mach number flows is the presence of the time-dependent base state, whose evolution is coupled to the evolution of the full solution. We also describe how to incorporate the expansion of the base state for full-star flows, which involves a novel mapping technique between the one-dimensional base state and the Cartesian grid, as well as a number of overall improvements to the algorithm. We examine the efficiency and accuracy of our adaptive code, and demonstrate that it is suitable for further study of our initial scientific application, the convective phase of Type Ia supernovae.
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Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:The convective period leading up to a Type Ia supernova (SNIa) explosion is characterized by very low Mach number flows, requiringhydrodynamical methods well-suited to long-time integration. We continuethe development of the low Mach number Equation Set for stellar scaleflows by incorporating the effects of heat release due to externalsources. Low Mach number hydrodynamics Equations with a time-dependentbackground state are derived, and a numerical method based on theapproximate projection formalism is presented. We demonstrate throughvalidation with a fully compressible hydrodynamics code that this lowMach number model accurately captures the expansion of the stellaratmosphere as well as the local dynamics due to external heat sources.This algorithm provides the basis for an efficient simulation tool forstudying the ignition of SNe Ia.
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Low mach number modeling of type Ia supernovae. I. Hydrodynamics
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and a savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional anelastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
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Low Mach Number Modeling of Type Ia Supernovae
The Astrophysical Journal, 2005Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
John B. Bell - One of the best experts on this subject based on the ideXlab platform.
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MAESTRO: AN ADAPTIVE LOW MACH NUMBER HYDRODYNAMICS ALGORITHM FOR STELLAR FLOWS
The Astrophysical Journal Supplement Series, 2010Co-Authors: Andrew Nonaka, Michael J. Lijewski, John B. Bell, Ann S. Almgren, C. M. Malone, Michael ZingaleAbstract:Many astrophysical phenomena are highly subsonic, requiring specialized numerical methods suitable for long-time integration. In a series of earlier papers we described the development of MAESTRO, a low Mach number stellar hydrodynamics code that can be used to simulate long-time, low-speed flows that would be prohibitively expensive to model using traditional compressible codes. MAESTRO is based on an Equation Set derived using low Mach number asymptotics; this Equation Set does not explicitly track acoustic waves and thus allows a significant increase in the time step. MAESTRO is suitable for two- and three-dimensional local atmospheric flows as well as three-dimensional full-star flows. Here, we continue the development of MAESTRO by incorporating adaptive mesh refinement (AMR). The primary difference between MAESTRO and other structured grid AMR approaches for incompressible and low Mach number flows is the presence of the time-dependent base state, whose evolution is coupled to the evolution of the full solution. We also describe how to incorporate the expansion of the base state for full-star flows, which involves a novel mapping technique between the one-dimensional base state and the Cartesian grid, as well as a number of overall improvements to the algorithm. We examine the efficiency and accuracy of our adaptive code, and demonstrate that it is suitable for further study of our initial scientific application, the convective phase of Type Ia supernovae.
-
Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:The convective period leading up to a Type Ia supernova (SNIa) explosion is characterized by very low Mach number flows, requiringhydrodynamical methods well-suited to long-time integration. We continuethe development of the low Mach number Equation Set for stellar scaleflows by incorporating the effects of heat release due to externalsources. Low Mach number hydrodynamics Equations with a time-dependentbackground state are derived, and a numerical method based on theapproximate projection formalism is presented. We demonstrate throughvalidation with a fully compressible hydrodynamics code that this lowMach number model accurately captures the expansion of the stellaratmosphere as well as the local dynamics due to external heat sources.This algorithm provides the basis for an efficient simulation tool forstudying the ignition of SNe Ia.
-
Low mach number modeling of type Ia supernovae. I. Hydrodynamics
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and a savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional anelastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
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Low Mach Number Modeling of Type Ia Supernovae
The Astrophysical Journal, 2005Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
Charles A. Rendleman - One of the best experts on this subject based on the ideXlab platform.
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Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:The convective period leading up to a Type Ia supernova (SNIa) explosion is characterized by very low Mach number flows, requiringhydrodynamical methods well-suited to long-time integration. We continuethe development of the low Mach number Equation Set for stellar scaleflows by incorporating the effects of heat release due to externalsources. Low Mach number hydrodynamics Equations with a time-dependentbackground state are derived, and a numerical method based on theapproximate projection formalism is presented. We demonstrate throughvalidation with a fully compressible hydrodynamics code that this lowMach number model accurately captures the expansion of the stellaratmosphere as well as the local dynamics due to external heat sources.This algorithm provides the basis for an efficient simulation tool forstudying the ignition of SNe Ia.
-
Low mach number modeling of type Ia supernovae. I. Hydrodynamics
The Astrophysical Journal, 2006Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and a savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional anelastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.
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Low Mach Number Modeling of Type Ia Supernovae
The Astrophysical Journal, 2005Co-Authors: Ann S. Almgren, John B. Bell, Charles A. Rendleman, Michael ZingaleAbstract:We introduce a low Mach number Equation Set for the large-scale numerical simulation of carbon-oxygen white dwarfs experiencing a thermonuclear deflagration. Since most of the interesting physics in a Type Ia supernova transpires at Mach numbers from 0.01 to 0.1, such an approach enables both a considerable increase in accuracy and savings in computer time compared with frequently used compressible codes. Our Equation Set is derived from the fully compressible Equations using low Mach number asymptotics, but without any restriction on the size of perturbations in density or temperature. Comparisons with simulations that use the fully compressible Equations validate the low Mach number model in regimes where both are applicable. Comparisons to simulations based on the more traditional an elastic approximation also demonstrate the agreement of these models in the regime for which the anelastic approximation is valid. For low Mach number flows with potentially finite amplitude variations in density and temperature, the low Mach number model overcomes the limitations of each of the more traditional models and can serve as the basis for an accurate and efficient simulation tool.